THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA LOS ANGELES GIFT / UM^Co APPLIED PRINCIPLES OF FIELD FORTIFICATION FOR LINE OFFICERS By J. A. WOODRUFF, Captain, Corps of Engineers, U.S.A. Instructor, Department of Engineering, Army Staff College, Fort Leavenworth, Kansas. Formerly Instructor, Department of Civil and Military Engineering. U. S. Military Academy, West Point, N. Y. Adopted by Direction of the Commandant for Use in the Service Schools at Fort Leavenworth. 1909. Copyright, 1909, By J. A. Woodruff. PRESS OF KETCHESON PRINTING CO., LEAVENWORTH, KANSAS. U(? (J^6< PREFACE The following pages are written with the idea of furnishing the members of the Army School of the Line and Staff College a guide in the solution of field problems in fortification. These problems are such that any line officer might be called upon to solve in actual service. Their careful solution on varied terrain in time of peace will give an officer confidence and skill in their solution in time of war, and will avoid many costly delays and mistakes. It is intended that this book be used with the Engineer Field Manual, Part V, on Field Fortification, so that most of the details of the subject contained in that manual are omitted. The author desires to acknowledge assistance received from Captain Edwin T. Cole, Sixth Infantry, Senior Instructor; Captain C. O. Sherrill, Corps of Engineers; and First Lieutenant G. C. Mar- shall, Twenty-fourth Infantry, Instructors, Department of Engineer- ing, Army Service Schools, for many valuable suggestions. Also to Sergeant John Howry, First Battalion of Engineers, for the prepara- tion of the plates herein. J. A. WOODRUFF, Captain, Corps of Engineers, U. S. A. Army Service Schools, Fort Leavenworth, Kansas, February 15, 1909. 939598 LIST OF BOOKS CONSULTED. Engineer Field Manual, Part V War Department. Field Fortification Fiebeger. Field Fortification and Field Engineering L. A. Beach. Field Fortification Work and the Present Arma- ment Clergerie. (Translated from the French by Captain W. D. Connor, Corps of Engineers.) Feldbefestigung V. Brunner. Field Service Regulations War Department. Fortification Clarke. Influence of the Experience of the Siege of Port Arthur Upon the Construction of Modern Fortresses V. Schwartz. (Translated troni the Russian in the M. I. D. General Staff.) Letters on Applied Tactics Griepenkerl. Notes on Field Engineering from the Diary of an Engineer at Port Arthur Engineer School. (Translated from the Russian in the M. I. D. General Staff.) The Principles of Land Defense Thuillier. Reports of Military Observers Attached to the Armies in Manchuria During the Russo-Japa- nese War .... War Department. A Staff Officer's Scrap Book Ian Hamilton. Text Book of Field Engineering Phillips. War in Practice Baden Powell. CONTENTS CHAPTER I. GENERAL PRINCIPLES. Page Type designs useless. — Connection between fortification and tactics. — Tactical aspects of fortification. — Importance of fortification. — Classes of defensive positions. — An intrenched camp. — A defensive line. — Advanced positions. — Second line. — Tactical situation of the works. — Intervals. — Mam roads. — Form of supporting points. — Conditions to be sought for in laying out or constructing works. — Artillery posi- tions. — Precedence of infantry. — Concealment of the inte- rior of the defended position. — Command. — Location of works in second line. — Means of communication. — Lines of retreat 9 CHAPTER II. TACTICAL ORGANIZATION OF INFANTRY IN DEFENSE. Division into sections. — Strength of first line, supports and re- serves. — Position of section reserve. — The garrison of the points of support of the second line. — General reserve 27 CHAPTER III. TACTICAL EMPLOYMENT OF ARTILLERY IN DEFENSE. Disposition of the artillery. — Mobility. — Armament. — Location of the emplacements. — Dispersion. — Position with reference to the infantry. — Location of guns. — Location of howitzers. — Indirect fire for guns. — Rapid fire guns. — Field guns. — Machine guns 31 CHAPTER IV. DESIGN OF INFANTRY WORKS. Designs not rigid.— General objects to be aimed at. — General character of supportmg points. — Redouts. — Variation in Page profiles. — Effect of weapons. — Profiles. — Head cover. — Back- ground. — Arrangement for fire to the rear. — Overhead cover. Lookouts. — Magazine accomodations. — Length of trenches. Location of trenches. — Field of fire. — Communication with the rear.— Cover for supports. — Drainage. — Telephone com- munication. — Obstacles. — Clearing the foreground. — Houses or villages. — Woods. — Concealment. — Dummy trenches or parapets 37 CHAPTER V. ARTILLERY POSITIONS. Low command and concealment. — Form of emplacement. — Posi- tions for light guns. — Indirect fire. — Expense magazines. — Means of access. — Observing stations. — Use of balloons. — Emplacement for machine guns 76 CHAPTER VL AUXILIARY MEANS OF DEFENSE. Electric searchlights. — Interior communications. — Telegraphic and Telephonic communication. — Water supply 85 CHAPTER VII. STRENGTH OF GARRISON. Determining considerations. — Hasty occupation of a position. — More deliberate occupation. — An elaborately prepared posi- tion. — Strength of infantry. — Artillery. — General reserve. — Examples •. 88 CHAPTER VIII. DEFENSE OF SMALL ISOLATED POSTS OCCUPIED BY DETACHMENTS. Modification necessary. — A very small position. — Form of works. All-around defense. — Position of works. — Enemy uncivilized or unprovided with artillery 92 CHAPTER IX. FORTIFICATIONS ON THE OFFENSIVE. General ch iracter. — Fortifications on the battlefield. — Location. — Tactical intrenchments. — Siege operations 95 CHAPTER X. CALCULATION OF TIME AND MEN REQUIRED TO EXECUTE DEFENSIVE WORKS. Page Tasks. — Double gangs. — Traction ditchers. — Redouts. — Firing trenches. — Overhead cover. — Communicating trenches, — Gun pit. — Observmg station. — Machine gun emplacement. — Table 100 CHAPTER XI. FIELD PROBLEMS IN FORTIFICATION. Relation to terrain exercises. — Staff class course. — Chief value. — General instructions. — Advanced method. — Three prob- lems with solutions 105 APPENDIX. Tools carried by the different arms 127 APPLIED PRINCIPLES -OF- FIELD FORTIFICATION FOR LINE OFFICERS. CHAPTER I. General Principles. 1. In the following discussion no attempt will be made to lay down rules or to establish typical forms of works that will be suitable to all circumstances. It should be remembered that the true essentials of a forti- fied position cannot be expressed on plans and maps. The disposition and the design of the defensive works should be decided on the actual ground to be defended, and only after a full consideration of the tactical circumstances. As the tactical considerations will vary greatly in different cases, it would be impossible, even if it were advisable, to lay down any system which would be applicable to all. Even the design of the individual works depends solely on the tactical considerations. Type designs are therefore useless, except as a general guide. 2. Fortification is intimately connected zvith Tactics, so much so that it would hardly be too much to say that Fortification is itself but a special branch of Tactics and not a separate division of the Military Art. Though the purely technical parts of the subject are assigned to the Engineers, yet a knowledge of the correct tactical 10 disposition and employment of defensive works is a necessity for every soldier. 3. The tactical aspect of Fortification lies in its adap- tation to the natural features of the ground and to the nature of the weapons employed by either side; tactical considerations, based principally on the above, but also on the probable direction, nature, strength, and other conditions of the expected attack, will govern the general dispositions of the defensive measures, the strength of the garrison and the armament required. 4. It is the history of all modern wars that the men do not take kindly to the spade, and it is only through bitter experience that they learn the value of intrench- ments. Every effort should be made, therefore, by the officers to impress this fact upon their men and, if pos- sible, teach them the lesson at the outset, and before the enemy has the opportunity of doing so in a more forceful and costly manner. Major Carl Reichmann, in his report on the Russo- Japanese War, states : "It may be truthfully said of the Russians, and probably of the Japanese also, that when they did not march or fight they dug." Major J. F. Morrison states : "Great reliance was placed on field intrenchments, and their use was very general. Once in the presence of the enemy the intrench- ing tool seemed next in importance to the rifle and ammunition. The rule on both sides seemed to be to always cover their positions with intrenchments as soon as taken up, even when held only for a short time." 5. Classes of Defensive Positions. — Defensive posi- tions may vary from the great extensive fortified position guarding some important city or strategic point liable to 11 be assailed by a formidable force and therefore requir- ing an army for its defense, to a small fortified post holding a road, a pass or a bridge head, and occupied by a small detachment. Again, the methods of defense vary according to the weapons that may be used by the expected attacking force, and many of the measures that would be neces- sary against a force employing siege guns, howitzers and mortars would be unnecessary against a force with field guns alone, or without any artillery. When troops occupy a defensive position for a con- siderable length of time, the field fortifications thrown up hastily at the beginning of the period will, by an energetic commander, be increased in strength until they attain a resisting" power approximating tliat of perma- nent fortifications. The position may be prepared : first, as a line bar- ring advance along some natural line of operations ; second, to surround some important nucleus whicli it has been determined to hold as long as possible. A position of the first class will be held by the defend- ing force as long as may be done without subjecting it to being surrounded and ultimately captured. The posi- tion of the Russians at Liaoyang and on the Sha River are illustrative of this class. In the positions of the second class, the intention is to hold tEe' position for as long a time as possible, and this usually involves the sacrifice of the defending force. SucTr pDsiridns are usually occupied by permanent forti- fications, often supplemented by field works, as at Port Arthur. But examples in field fortification may be found in Plevna, Vicksburg, Petersburg and Sebastopol. Any field army may therefore be called up to defend 12 a fortified position, and such operation may include all the refinements of regular sieg;e operations. Major J. E. Kuhn states : "I am of the opinion that a defensive position properly prepared and skilfully adapted to the ground will impose upon the attack meth- ods analogous to those employed in sieges, and this without recourse to any very elaborate works of con- struction." 6. A^v_Jntrenched camp or an all-around defensive position would consist at the present day of a series of fortified and strongly held positions surrounding the town or other object to be defended, and so situated in tactical relation to each other that it would be impossible for an attacker to penetrate to the interior of the defensive line without first capturing some of these positions. The distance of the defensive line from the nucleus would in almost all cases be decided by the topography, but this line should be so selected as to prevent the enemy from locating any batteries within a range less than 10.000 yards from the nucleus, if aimed and ob- served fire is possible from the location. Sometimes it will be sufficient to keep the enemy's position out of sight of the town, as unaimed and unob- served fire will seldom be effective, and it may happen that a conveniently intervening range of hills would effect this; it should, however, be remembered that ob- servation of fire can be conducted with sufficient accuracy to hit a town or other large area from captive balloons, so the end would not be achieved if the town could be seen from balloons sent up from the besieger's positions, if the latter were within range. It will seldom be wise in the case of a large and im- portant town to rely on a single line of fortified positions 13 for its defense. Therefore, it is often desirable to keep the main defensive line at a considerable distance from the nucleus in order to leave room for a second line or retired position, in case some of the works in the front line are captured. 7. A Defensive Line. — The above principles apply equally to cases where the position is a straight line or an arc with secured flanks. It is imperative, however, in such cases that the flanks cannot be turned. The defensive organization of the flanks of any posi- tion merits special attention not only because the best location for the troops that cannot be made use of in the fortifications themselves will be in outflanking eche- lons in rear, but also because this' disposition, for the points of support on the flanks, must be adopted in pref- erence to a break to the rear in the general line of defense. It moreover favors counter attacks upon the flank of the adversary and renders much more eas}^ the execution of these outflanking movem.ents whose object is to envelop the enemy's wings. 8. Advanced positions in front of the main line of defense often are of considerable value in delaying the besieger's progress and prolonging the defense. They form good pivots for the outpost line ; they force the be- siegers to deploy or to commence their siege works at a much greater distance from the place; they may even possibly necessitate a regular formal attack being under- taken against themselves, before the besieger can turn his attention to the main works. They cause, in fact, delay, which is of priceless value in a siege. They should be selected so as to necessarily force the besiegers to stay their advance till they are taken. 14 They should be proof against assauh over the open, and the communications to them from the main position should be secure and hidden, so that it is possible to reinforce them or withdraw their garrisons unseen. The positions should be commanded by the artillery and the infantry positions of the main line, so as to deny their use to the enemy after they have been vacated; and the works constructed on them should be of such a nature as to give no cover to the enemy. Placed so as to easily overlook the approaches to the position, these points of support will frequently occupy the military crest or some similar position: but they must be chosen and organized so as to allow no part of them to be seen by the enemy from a distance. The points of support of the advanced line must, moreover, satisfy as far as possible the condition of per- mitting an easy retreat. The latter should be prepared so as not to incommode the action of the line in rear, which constitutes the main or principal line of combat. The advanced line will not always exist, but it will often be useful and possible to construct one, and the use of it will certainly be more frecjuent in the future than it has been in the past. When it does exist the resistance that it will furnish ought to be sustained as long as possible, so as to make the enemy believe that he is already in front of the main line, and to cause the attack to make great preparations to carry this line, and perhaps to make him attempt a decisive attack and thus make a useless attack, which will result in his arriving- in a most critical condition in front of the main line. It may occasionally happen that a point exists in front of the defensive line which would afford a very com- manding position at short range for the enemy, and which / 15 therefore must be occupied and held at all costs. This case is different from that of an ordinary advanced work which it is intended to vacate ultimately. Such a post must be made as strong and secure as possible, and the defenders must be given to understand that they have to hold out to the last. If covered communications can- not be provided, reliefs, supplies, etc.. must be carried up at night only. 9. Second Line. — The object of the second line is, in the event of. one of the positions in the main line having been captured, to oppose a bar to the further advance of tlie besiegers. Also these retired works will form pivots for the action of the general reserve, in the event of any of the besieger's troops penetrating the front line by any means. T he second lin^ must not be commanded by the first, for in case a portion of the first line were captured, the attackers would be able to render the works of the sec- ond line untenalile. It must be placed so that it is not subjected to the fire of an attack which is made upon the main line ; it must be near enough to immediately receive the assailant under its fire as he starts to attack it. It will therefore ha\e to be in a good position, if such a one can b e found, _ abgu^ 50 or 600 yards _b ehind the first line. The works should, if possible, be arranged so as to bring a heavy fire upon the rear of the works in the front line in the event of their being captured ; also so that the attackers cannot make a dash between them upon the town or place defended. A continuous enciente is totally unsuitable. Detached works or groups of works on tactical points are infinitely better, and it will often be found that one powerful group of works on a com- 16 manding but retired position will successfully dominate a large section of the defensive area. For their general disposition and design, the descriptions given in the case of the main works apph^ equally well, except that as a general rule they need not be so strong, and in many cases concealment will not be so necessary. 10. Tactical Situation of the Works. — There are three prime conditions to which every defensive position should conform : 1. It should admit of full scope for the effective use of the defender's weapons. 2. It should restrict, as far as possible, the effect of the attacker's weapons. 3. It should provide full facilities for tactical con- trol and movement of the defender's forces. If a hill or other commanding feature be occupied by some of the defender's troops in such a manner that they can sweep with the fire of their weapons the ground in front and on both flanks of it, then none of the at- tacker's troops can pass by that position within the limits of effective range of the weapons of the troops holding it. If the defenders hold two such positions situated at such a distance apart that the occupants can sweep with their fire the whole of the ground between them, then the enemy would be unable to pass between the two, or within effective range of their outer flanks. A series of positions all around the town arranged in the above manner, so that the ground between every pair can be swept by rifle fire from the works, or artillery fire in rear, would make it impossible for the enemy to pene- trate without capturing one or more of the fortified posi- tions. 17 The organization of a defensive field of battle includes the utilization of natural points of support, such as woods, villages and forests, and the creation of artificial points of support. The necessity of establishing con nection between the action of the various points o^ support over the entire extent of a defensive positior does not always permit the choice of the most favoraLe site for each of them, but nevertheless, since there is considerable latitude in the location of the whole posi- tion and as the location of the interpolated works can often be varied within certain limits, it is well to state the advantages that are given to each point of support oy the position that it occupies upon the ground. (See paragraphs 18 and 53.) 11. The intervals between the supporting points would not necessarily be all the same. Where-the g^-ound in the intervals is absolutely open and flat it might extend up to 2,000 to 2,500 yards; where it is le^ favorable it might be necessary to make jt only 1^^000 yards or even less. If the ground is very broken, so that there is much space concealed from view from either of the adjoining works, subsidiary works or trenches might be necessary in the intervals to cover the dead ground. On the other hand, these intervals may evidently be increased when the terrain can be covered both in front and on the flanks by a fire of artillery. 12. All main roads or other lines of approach by which an attacker's columns would probably advance should be covered by the fire of positions such as the above. Machine guns and artillery should also be placed so as to sweep them. 13. Form of Supporting Points. — It is now neces- sary to consider what will be the form of the supporting points above mentioned. Anything in the nature of a fort or redout must always form a more or less con- spicuous target, and be certain of receiving a heavy an«f. concentrated fire from the besieger's batteries. The in- terior of a redout will necessarily be somewhat crowded, and heavy explosive shells dropped into crowded re- stricted spaces are known to have a most destructive effect. (See paragraph 42.) It is quite possible, on account of the greatly increased defensive power of the rifles of the present day, to space the defenders of a line of parapet at much greater dis- tances apart than was the rule in past times. A line of men with magazine rifles, four to six paces apart, behind good cover, can bring such a hail of bullets over the open ground in their front to a considerable distance from their own position as to effect terrible loss on any troops endeavoring to advance on it. Such dispersion, moreover, is advantageous in that it reduces the risk of casualties from the hostile fire, and in an immovable defensive position cannot be con- sidered too great for effective supervision and control. (See Chapter VII. and the last part of paragraph 45.) It seems probable, therefore, that each of the detached points that go to make up a great defensive position would consist merely of a locality or tract of ground ren- dered defensible by a skilful treatment of its natural feat- ures; that is to say, by the provision of simple trenches or jg^rapets, in such a manner as to interfere as little as possible with the natural appearance of the ground. The organization to be given to a point of support depends upon the tactical circumstances of the moment, upon the number of men that must defend it, upon the 19 role that it must play in the action as a whole, upon the subdivision that the commander of the defense intends to make of his forces between the garrison of the works which will form the fixed line, and the maneuvering troops, and upon the manner in which he intends to employ these last-named troops. Major W. V. Judson, in his report on the Russo- Japanese War, states: "A fortified line, whether its plan be a closed figure embracing a city, or a straight or broken line marking the front of an army, should be marked by the absence of local and congested defen- sive units, which would simply form satisfactory targets for the enemy's artillery. "Troops will and should be trained with great care in night marching and night attack. The difficulties for- merly dwelt upon in connection with night attacks may be overcome by careful practice. Drill regulations should treat especially of methods and formations for conduct- ing such operations. "Now, the effect of this certainty of night attack is to render insecure the defense of intervals between works or between fortified pi\-ots. The properly fortified line then becomes continuous. Individ ual work s are ordin- arily but short trenches^ conforming to the ground. These short trenches are not in a continuous line parallel to the front, but occupy what may be called a defensive belt, of a widtHjvarying between 200 or 300 yards and half a mile, depending upon the ground and the importance of the sector. Each of the small units is of the least pos- sible depth (extension in the line of fire). Many should be provided with bomb-proofs. Some should be designed for fire either to front or rear. Trenches subject to enfilading fire should be of short length or broken and 20 well traversed. Deep covered communications, either zigzagged or traversed, should be multiplied within th's belt, and connect the works with the naturally or artifi- cially protected places for the supports. Two to four miles inside the belt, approximately parallel thereto, but concealed wherever possible by the folds of the ground or by vegetation, should be a road as well built as pos- sible, of a width up to 60 or 80 feet for grand positions. Along the road are situated the headquarters of larger units, most of the reserves and depots of ammunitions, food supply, etc. From this great road, which would often be paralleled by rails, should branch out fan-shaped, a system of narrower roads connecting it with the sup- ports behind the belt. These roads, especially toward the front, should be located with the greatest care to secure concealment, and, in places, might have to be sunken or traversed. "It has been held that ease of command and control would be sacrificed if a fortified line were of the char- acter advocated herein. This is true io :i certain extent, just as command and control are sacrificed when the skir- mish line is used. But in the case of tlie fortified line a sufficient installation of telephones vVill tend to remedy the evil. The Russians had four or five telephones to the mile, along the fortified belt, in addition to many behind it, and in addition to telephones for fire direction of ar- tillery. "With three or four thousand men to the mile of front, including all reserves, a fortified line of the belt type is invulnerable to frontal attack. It cannot be shaken by artillery fire, as the troops are protected against shrapnel, while the chances of hits by explosive shells are 21 exceedingly small, and the results of such hits are not serious." 14. The conditions that should be sought for in laying out or constructing these trenches or parapets should be, as in all other defensive works : 1. A good field of fire over all the ground over which the enemy could advance. 2. As great a measure of invisibility as it would be possible to obtain under the local conditions. 3. Good cover from rifle and ordinary artillery fire 4. Good covered and concealed means of communi- cation with all parts of the position. 15. Artillery Positions. — The guns of the defense should be placed in such situation as would afford the greatest scope for their fire, combined with as great a measure of invisibility as the circumstances will admit of, and also with the power of unobserved removal and bringing up. They need not necessarily be clear of the infantry portions of the fortified positions, for the con- ditions are very different from those which prevailed in the confined forts of the old type. In extended positions of the type above described, it would not be difficult to find for the guns sites so placed that they would not draw on the infantry trenches the hostile artillery fire. It might often be that the best sites would be on the flanks of the infantry, but it is not necessarily so, and they might sometimes be placed so as to fire over them. (See Chapter V and paragraph 18.) Major Kuhn states: "The Japanese showed great attention to the subject of concealment in selecting their gun positions; much of the firing was mdirect. Where 22 no natural concealment existed, artificial concealment was provided, if possible. "The artillery positions shonld, wherever possible, be located at some little distance to the rear or flank of the infantry trenches and at a safe distance from positions of supports, reserves, magazines, or anything else which one desires to protect from hostile fire. High angle fire is a little wild at the best, while direct fire gives a large danger zone to the rear from ricochet shots. Anything near the artillery positions will come in for a good bit of exposure from fire directed at the artillery, hence the importance of keeping the latter somewhat sep- arated from other elements of the defense." 16. Precedence of Infantry. — If there is any ques- tion as to whether guns or infantry shall occupy any particular site, the way to settle it is to consider, not which arm is most suited for, but which form of fire it is important to have at that particular point. Generally it will be found that infantry fire is the more essential, for it must always be remembered that rifle fire forms the bedrock of all defense, and that artillery fire is but an accessory — a highly important one, but still never more than an accessory. It will generally also be found possible to find another site for guns from which the same, or nearly the same, effect can be produced, as from the point in ciuestion, while it may sometimes be dan- gerous to leave it without infantry defense. 17. Concealment of the Interior of the Defended Position. — It is of great advantage if the main defensive line can have the ground steeply sloping away from it in its immediate rear. Not only would such a conforma- tion make it easy to provide cover for local reserves and for the defender's encampments, but it would conceal 23 from the enemy's view all that went on within the de- fender's lines. The latter condition is of infinite value and worth many sacrifices to obtain. At all events the general position taken up should, if possible, be one that admits of situations being found out of view of the enemy for the camping grounds of the defending troops ; and also of the communications being concealed. If the latter cannot be achieved by natural means, it should by artificial. 18. Command. — It is generally considered very ad- vantageous to place the defending works, if possible, on commanding heights. It is doubtful, however, whether beyond a certain point this is an advantage. Infantry fire with the low trajectory rifles of the present day is less effective from a height than from a low site. It is best to as near as possible graze the surface of the ground over which the attackers must advance. The same argu- ment applies to the fire of low-trajectory, high-velocity guns; with these ag^ainst troops in the open it is desirable to burst the shrapnel with as flat or grazing a trajectory as possible. For fire, either of guns or howitzers against works, an elevated position gives better searching effect, but at longe range this does not make so much difference as is generally supposed. A high site for a defensive position has also certain positive disadvantages. Hardly any hillsides are at a uniform glacis-like slope all the way up. If they are convex in section, it is impossible to avoid having a good deal of hillside and ground at the foot hidden from the defender's positions, and there- fore the attackers can advance up it unseen and un- harmed. If it is concave, then to be able to see and fire all down the slope, the defenders are obliged to expose themselves greatly to direct fire. Moreover, on an ele- vated position the attacker's artillery can safely keep up a heavy fire over the heads of their advancing infantry till the very last moment. Elevated positions derive a certain amount of ad- vantage from the fact that it is less easy for the works to be searched out by the fire of the attacker's artillery. But well-concealed, narrow, trench-like works have in any case little to fear from this form of fire. A more positive advantage is found in the fact that elevated po- sitions, such as those on ridges, lines of hills, etc., will nearly always give concealment from the enemy's view to the interior of the defended area. Similarly such posi- tions permit of a range of view over the attacker's positions and enable the defenders to note his movements. Observation of artillery fire is also more accurately car- ried out from elevated positions. For these last reasons, therefore, it is desirable for a defensive position to have a certain amount of command over the ground over which the enemy must advance. The actual height, however, need only be sufficient to give a good view over the ground in front, particularly to clear all obstacles to vision, such as crops, trees, under- growth, etc., and also to obtain concealment for the in- terior of the defender's lines. With flat, open country it may be very little indeed. The slopes to the front should be as gentle and evenly sloping as possible. Major Kuhn states : ''From what I saw in Man- churia, I was strongly impressed by the fact that the disadvantages of a commanding position often, and gen- erally, outweigh the advantages." In commenting on the location of the Russian defenses on the highest ridges and hills, General Ian Hamilton states in his "Staff Officer's Scrap Book" : 'T am be- 25 coming increasingly certain, as I gain in experience, that the defense Hnes of the forbidding, precipitous type are in truth generally more open to attack than a simple, gently rising terrain, which furnishes those who hold it with a wide, smooth field of fire and good positions for their guns." 19. Location of Works in the Second Line. — The same general principles apply to the selection of the sites for works or supporting points in the second or retired line. It should be possible to bring from it a concen- trated and heavy fire on any part of the outer line which has been captured, and to confront the assailants with a fresh series of works which must be carried before they can reach the object of their efforts. 20. Good means of communication between all parts of the general line of defense, and also from the town or headquarters to all points on the line, are of vital importance. The facility with which artillery and the reserves will be able to move in every direction in rear of the line of battle constitutes an element of enormous weight which must be prepared for with the greatest care, and which may demand the opening of passages through woods, the construction of small bridges across streams, etc. (See paragraphs 13 and 75.) 21. Lines of Retreat. — Since is is necessary to fore- see everything, the commander will look into the eventual- ity of a retreat, and will cause to be made all the necessary preparations to insure, if necessary, its good execution and to prevent the enemy from changing it into a rout. The preparation for the retreat will comprise the works of communication and the organization of points of 26 support for the retreat. These last will consist of posi- tions of limited extent barring the roads and covering especially certain points that must be passed, such as bridges or various other positions at which a small force could stop the enemy quite a long time and make him lose contact with the main body of the forces, and insure the safe passage of the latter. These points of support should be echeloned in depth and the artillery will play the principal role in their defense. 27 CHAPTER II. Tactical Organization of Infantry in Defense. 22. Division into Sections. — A large fortress or de- fensive position would be far too extensive for all the troops to be directly supervised by one man. It should therefore be sub-divided for purposes of command into several sections, each under the command of an officer with a suitable staff. Each section should be completely independent, both tactically and as regards administration; subject, of course, to the general control of the fortress commander. 23. Strength of the First Line, Supports and Re- serves. — Every fortified post in the front line of the section would be occupied by its own infantry garrison. In rear of the works, if possible close to them and never over 300 yards distant from them, and under good cover, will be the supports, whose strength would vary accord- ing to the necessities of the case, but would generally be from one-half to two-thirds of that of the garrison of the post. Then in rear again and at a central position as regards the whole section, would be the local or "sec- tion" reserve. Its strength would depend upon the defensive strength of the works along the front of the section. If the latter were strong and the means of communication to them were good and not long, the number of troops in the works, including their imme- diate supports, could be kept low, and the number in reserve increased. The advantage of this would be that it would relieve as large a number of troops as possible 28 from an exhausting and demoralizing life in the advance works under constant shell fire. If, however, the nature of the ground made the outer defensive position a weak one, or if the reinforcements could not reach them with- out long delays, then a considerable number of troops must be kept well up to the front, and the reserve would be proportionately less. The artillery belonging to the section would usually remain either in emplacements in the front line or under cover close in rear. There might, however, be some light pieces with the section reserve troops. The works will most frequently be combined, for the purpose of command, into groups which one battalion can defend, one portion of its defenders forming the garrison for the trenches and the other part a movable force in support, intended either to reinforce the line of fire or to be used in counter attack. Dependent upon circum- stances, the battalion will ordinarily have either two com- panies in garrison in the trenches and two in support, or three companies in the trenches and one in support. This last subdivision is suitable for a point of support which is expected to offer only a weak resistance, or to parts of the field of battle which are approachable by the adversary with difficulty and are provided with good flank protection; the parts easily approachable and from which a vigorous resistance must be demanded, on the contrary, will have a larger movable force. Taking into consideration the fact that the assailant will always try to bombard effectively with his artillery the works to be attacked and the approaches thereto, and that in consequence the movement from the rear to the front will be very difficult to execute without considerable losses, unless good covered approaches exist, the com- 29 panics of the garrison mnst have all of their numbers in the trenches, even thou^^h they wish at certain times to engage only a part of their forces and to keep a part for reinforcements. It seems, moreover, that the con- dition of never permitting the enemy to have the superi- ority of fire demands that, at a given moment, it should be possible to place the whole company in line imme- diately; and this will be most easily secured in the described manner. 24. The position of the section reserve would form the headquarters of the section, and should be out of sight of the enemy. It should also be on or near a main radial road of communication, and from the camp a road or roads should lead to different parts of the front line. It should be connected by telephone with each of the fortified positions in the defensive line, with headquarters and the main depots. 25. The points of support of the second line, like those of the first, ought always to have their fixed garri- son without counting upon the movable troops ; this is the only means of being certain that the works will be occupied at the proper moment. In case of taking up the offensive again, they will have to be abandoned, and the units charged with their defense will then constitute the reserve. 26. General Reserve. — In addition to the section re- serves there should be in all cases a general reserve for the whole position. It should be encamped in a central location and should be of as mobile a nature as is prac- ticable. The disadvantages of the great extent of the position. which has to be taken up for defense at the present day, 30 is largely neutralized if a considerable portion of the defenders are kept as a mobile reserve force, as the for- tified positions may in such case be few in number and far apart; they should, however, always be individually strong. 31 CHAPTER III. Tactical Employment of Artillery in Defense. 27. The disposition of the artillery will be different from that of the infantry. It will not usually be desir- able to keep any of the heavier guns or howitzers in the center of the defended area as a general reserve. As a general rule, it will be required to have all the heavy artillery iji the front line from the very beginning of the siege, in order to crush the besieger's guns, and prevent his building batteries, so that only the shorter ranging pieces sTiouId^lbe kept in rear. If, Jiowever, the defense is very weak in artillery, the guns might have to be kept under cover so as to have them available for use in the later and more critical phases, particularly in the event of an assault. 28. Mobility. — All the guns should be movable and ther^shauld be a large number of alternate emplacements, and good and direct communications hidden from the enemy 's'^viewT' Mobility, in fact, is the chief factor. 29. Armament. — Generally speaking, the armament of a first-class fortress would consist mainly of howitzers and mortars from 5-inch caliber upwards. It would also have a certain number of long range heavy guns, such as the 6-inch ; also a proportion of less powerful pieces, which should be of the rapid-fire class, the 4.7-inch and long 12-pounder being the most useful sizes. Long range direct-fire guns are required to keep the attackers at a distance and to act upon them if they attempt to come out into the open; howitzers and mortars are required to 32 search out their trenches, drop heavy shells into their gun emplacements, break down overhead cover, and search hollow ground, reverse slopes of hills, ravines, and other places where they might find cover. Howitzers and mortars are ineffective at ranges under 1,000 yards, so that for this stage of the attack, guns only can be relied on. Shrapnel fire from guns is also recjuired against attackers in the open. The proportion of the guns to the howitzers and mor- tars will depend to a certain extent on the topography. If the ground in front is broken, affording abundant cover, and precluding long range fire, then howitzers and mortars should predominate. Where the foreground is" open for a long distance, or the defensive position very commanding, the proportion of guns might be greater. 30. The location of the emplacements for the heavy artillery will depend mainly upon the duty that each piece has to perform. Generally this duty is to operate against an enemy who is attacking the main supporting points. By this is meant that the defense of these points, rather than that of the intervals between them, is the object chiefly to be aimed at, for an attack through the intervals need not, as a rule, be feared. At the same time, means of bringing a cross fire over the intervals are not to be neglected. Certain also of the pieces, generally howitzers and mortars, will have specified duties to perform, such as to enfilade reverse slopes of hills, hollow ground or ravines, which are screened from frontal fire; and in gen- eral, the artillery positions will be so placed as to bring a heavy fire over all the ground to be traversed by the assailants. 31. The dispersion of the guns in an artillery posi- tion has several advantages. It renders it difficult for 33 the attackers to concentrate their fire; it brings a con- verging fire from a wide arc to bear on the object specified for attack; it permits of far greater latitude in the selec- tion of sites for emplacements and in taking advantage of the ground to obtain concealment, and it very con- siderably does away with the demoralizing effect pro- duced by a heavy shell fire in a comparatively small area. The guns should therefore be dispersed, but their fire must be capable of concentration by complete telephonic communication between the guns, observing stations and commanders. 32. Position zvith Reference to the Infantry. — If the existence of high ground in rear admits of it, the defend- ing artillery may fire over its own infantry positions, or the artillery itself may be in two tiers, the direct firing guns being in advance, and the howitzers, firing over them from retired positions. It may be necessary for some of the guns — for instance, those entrusted with the duty of enfilading hidden ground in front of the main position — to be placed well to the flank of the infantry positions ; that is to say, practically in the intervals be- tween the supporting points. In all such cases they require to be defended by infantry, for whom intrenched positions should be nrovided near them. (See paragraph 15.) It is not necessary that any of the guns may be able to defend their fronts by their own fire, as this duty can be more conveniently and effectively carried out by infantry. 33. Location of Guns. — A somewhat commanding position is an advantage for guns particularly for pur- poses of observation. If the sites are on a hill they are, for purposes of concealment, best placed a^little way down 34 from the crest ; at all events not on the sky line, pro- vided means of access are obtainable from the rear. It may sometimes, however, be better to put them in posi- tions somewhat drawn back from the crest of the hill. Here they will be less easy to hit. and the guns can be more easily withdrawn or brought up. It is possible that from such a position a good deal of ground at the foot of the hill could not be seen, but this could generally be dealt with by pieces from another part of the position. 34. Location of Hoivitsers and Mortars. — Howit zers and mortars, which can fire over an intervening ob- stacle, provided its height is not such as to intercept the projectile in its flight, and whose fire can be controlled from observing stations can, and would usually, be placed in retired situations on the reverse slope of hills, etc. Here they would be entirely unseen, and could hardly be hit. Good sites for observing stations would in such a case be of the first necessity, and these must obviously be as inconspicuous as possible. 35. Indirect Fire for Guns. — The heavy direct firing guns could also be fired in the same manner, if it were considered desirable to put them in retired positions ; but with low trajectory weapons such positions would be less easy to find, and such an arrangement would be almost certain to result in a considerable portion of the ground at medium and short ranges being screened from the guns; moreover it is undesirable to rely entirely on ob- 5er^'ing stations which may be wrecked, so it is better that nearly all the direct firing guns should be capable of being laid direct on their objects. (See paragraph 68.) 35 36. Rapid-Fire Guns. — In addition to the heavier types of guns, it is very desirable to have for use in the later stages of the siege a number of light guns of the rapid-fire class, such as 6-pounder and 3-pounder rapid- fire and the 1-pounder automatic or pom-pom. Guns of this class are of course useless against earthworks, but they fulfil most useful functions during the later stages of a siege. For instance, in the event of an assault they will assist in bringing an overwhelming fire to bear, and at any time should the besieger offer, even for a few moments, a target in the open, their rapidity of working will permit of the opportunity being availed of. For such guns there should be a number of alternate and well-concealed positions; the principle of their employment should be surprise, combination, and the taking advantage of every opportunity. 37. Field Guns. — A mimber of 3-inch field guns could also be most usefully employed in the defense of a fo rtr e s s. They need not be assigned to any particular positions, but might be kept with the reserv e troops and pushed up into any part of the front line when they are required. 38. Machine guns will fulfil a most useful purpose in a fortified position. They can be kept concealed when not in use, and even when in the act of firing, afford so small a target as to be hardly visible. A few such weapons in an intrenched position permit of the greater part of the garrison being kept well under cover; for in the event of an assault, they enable a heavy fire to be developed by their attendants. In the defense of a flank, in a position where a line of infantry would be visible and liable to enfilade fire, a single machine gun judiciously 36 posted behind a bush or rock or in a small pit could entirely escape observation. To cover particular points such as a bridge or ford, they are also most valuable. Every fortress, therefore, should be equipped with a good number of these useful v^^eapons. Each infantry v;rork should have some assigned to it, and there should also be a number in reserve. 37 CHAPTER IV. Design of Infantry Works. 39. It is undesirable to indicate more than the gen- eral principles of the design of the works. In order to make these clear it is necessary to give some designs, with the understanding that they are not at all rigid, and sliould be modified to suit the ground. 40. There are four general objects to be aimed at in preparing a given area for defense : 1. It should have the utmost development of fire to the front, and to a somewhat less degree to the flanks. 2. The works should be so arranged that they will offer as shallow a target to the enemy as possible. 3. They should be made inconspicuous and difficult to distinguish. 4. They should afford rapid and covered communi- cation from each work or part of the defensive line to the rear, so that supports may be brought up with the utmost rapidity, 41. General Character of the Supporting Points. — Along certain parts of the defensible ground, where a good field of fire in the required direction can be obtained, will be constructed lines of infantry parapet with cover in rear, connected by covered ways, perhaps with each other and certainly with the rear. On suitable positions for artillery fire will be constructed the emplacements for the guns, also with communications to the rear. The selection of both these infantry and gun positions will be governed by the four main principles stated above. 38 To permit of full scope for the defender's rifle fire, all that is needed is a simple parapet to fire over. In trace this should follow the contour of the ground, and should therefore seldom be straight, and never on any geometrical plan. (See paragraph 13.) It is necessary, in order to cover the field of fire com- pletely, that the works be traced along the military crest itself or simply on the gently sloping ground following approximately the contours of the ground. This disposition presents one great advantage ; which is, that it does not ofl^er to the eye of the enemy's observer any geometrical form betraying the work of man. No other plan will answer; the crest of fire, lending itself to all the changes of the ground, cannot be perceived, even at short ranges. Moreover, neither the trace nor the execution will be complicated. 42. Redouts cannot generally be used in situations exposed to artillery fire unless they can be so arranged that they cannot be recognized as such from the enemy's artillery positions. A favorable site is one which com- mands the ground around it to effective rifle range and is not visible from artillery ranges. In preparing a defensive position, if sites meeting the foregoing conditions can be found on which redouts can be built to flank the adjacent trenches, they should by all means be built. Redouts in good position in rear of a line form valuable supporting points. The Fort Riley redout (Fig. 205, E. F. M.) and the Russian and Japanese redouts (Figs. 1 and 2) are excel- lent types of a modern redout. (See paragraphs 102-4.) In speaking of the Shanlantzu redout. Major Kuhn states : "In my judgment, it has the best profile and trace of any seen during the war, affording good cover, small 39 artillery target, and strong frontal fire for infantry. The Japanese constructed a somewhat similar redout near Kangpienhsien and it is surmised that the Shanlantzu redout served as a model. ''The polygonal trace with a broad front and shallow depth appears to best meet the requirements for a closed work under modern conditions, affording a strong frontal fire and a minimum target to the artillery. While the reduction in depth of closed works imposed by the search- ing i)()\ver of artillery reduces the volume of flank fire and diminishes the value of such works in an extensive forti- fied line in fiat country, forts and redouts have not lost all their importance and are still needed to afford points of support to a defensive line. The employment of machine guns, moreover, enables small works with short flanks to deliver a volume of fire which makes the size of works and their garrison a matter of minor importance. "It is to be noted that none of the forts or redouts provide for the emplacement of artillery in their interiors. The artillery was placed either in the line of the trenches connecting the forts and redouts, or, more generally, in a retired position several hundred yards in rear of the front line. 'Tt is only in perfectly flat and unbroken country that redouts need approximate the type forms of closed works shown in text books. In ordinary diversified topography many points will be found which, with simple trenches, cover for men and ammunition and good approaches, will fulfil the requirements of redouts without the use of closed works." ^^ i i K Q ^*^^;^^i^ l- e e it )t n n s •s s t •t s ^ii^ Wirt. £ntanql€,iTfni Srtlana "^-^^ % Joseph £ KuJifi^ JAPANESE ffELD PEDOUBT N£AR KANGPlSNHSfEN. ff^jor „/ In^t^i o c 43 43. An introicJuncnt is a shield ; its object is to make the defender safe, either when at rest or when in the firing- position, against the action of the enemy's pro- jectiles ; its profile is therefore dependent upon the arma- ment in use. It must necessarily vary with that and undergo a parallel evolution. The profile depends furthermore, especially for in- trenchments made on the field of battle, upon the time that the defender can give to their execution. This time Vv-il! always be short, first, on account of the fatigue that can be imposed upon the troops and which must be re- duced to a minimum; and second, because it will not usually be possible to determine exactly, very long in advance, the ground of the struggle. 44. Effect of Wcopons. — The rifle and machine gun shoot a bullet whose ])enetrati()n in earth varies according to the arm. the distance and the nature of the soil, from 24 to 40 inches. This last penetration hardly applies except to clay at very short ranges. Thirty-two inches can be considered as the normal maximum. Shrapnel from field guns fired with a time fuse has no effect upon intrenchments which have a sufficient thickness to resist a rifle bullet. Tt can only have effect upon the defenders when the latter arc firing. Tt is powerless when the men are resting behind the parapet, either seated or lying down with their backs to tlie mass or protected by it under the sh^pe of about 1 on 4. The same shell fired with a percussion fuse pene- trates rather deeply into the earth of a recently con- structed parapet when the projectile falls upon the exterior slope. Upon bursting it may form craters as large as 60 inches in diameter and 20 inches in depth. But when the projectile falls upon the suj^erior slope, it 44 cuts out a furrow of not more than 6 to 8 inches in depth at the most, and carries away but httle earth. In other words, it ricochets. Such shells fired against men placed upon the banquette of an intrenchment produce but little effect. At 2,000 yards it can hardly be hoped to get more than one man wounded for every shell, even with a perfectly regulated fire. If the men are seated or lying down with their backs to the parapet, the result is practically nothing. In general, high explosive shells from field guns pro- duce no effect upon the unprotected personnel unless they burst very close to the object. They therefore re- quire very great accuracy of fire. Fired against earthen parapets in which they can enter, these shells give quite a considerable effect, but the complete destruction of this class of works can only be obtained by a prolonged fire, regulated with accuracy, which will always necessitate a relatively great expenditure of ammunition. The per- sonnel sheltered behind these parapets will suffer but lit- tle. Those shots alone which burst at the crest will pro- duce serious effects. But these shots must be considered as altogether accidental, however well regulated the fire may be. Shrapnel from siege guns fired with a time fuse has great efficiency against troops without cover up to a range of 7,ooo yards for guns and 5,000 yards for howitzers. But as soon as the personnel is materially sheltered the effect of these shells becomes ver}^ small, even with plung- ing fire, and can be completely nullified if the defenders protect themselves by light roofs such as hurdles covered with from 4 to 6 inches of earth, or by means of thick planks. Under these conditions the greater number of balls and pieces of shells are stopped. Fired with per- 45 cussion fuses against obstacles and accessory defenses, shrapnel has an effect very inferior to that of high ex- plosive shells of the same caliber. Like projectiles of small caliber, those of large caliber ricochet when they are fired so that the angle of fall is less than 17°. The ricochet can also be produced when the angle of fall varies between 17° and 30°, depending upon the initial velocity and the nature of the soil. When the shell ricochets, it explodes in the air, and then pro- duces very small and altogether uncertain results. When shells of large caliber are employed against a parapet, the shots which strike the crest are very effica- cious against the troops sheltered behind it, but, as with projectiles of small caliber, these shots will always be altogether accidental, even with a very well regulated fire. Practically all of the above effects were obtained in the test of the field redout at Fort Riley in 1907 (fig. 205, E.F.M.), where high explosive shells from field and siege guns, and siege howitzers were fired at the work; which has a triangular profile and low command. Prac- tically the only shells which penetrated the parapet and splinter-proofs were those of the 7-inch siege howitzer. (See Major Kuhn's comments, par. 46.) 45. Profiles. — From the above discussion on the effect of projectiles, the conditions which a good profile must satisfy are apparent. The exterior slope of the parapet should have an in- clination of not less than 1 on 5. This corresponds to an angle of about 11°, and the mean value of the angle of fall of projectiles from the present field guns is taken as 6°. With this slope, projectiles fired with a service charge from a field gun will nearly always ricochet. This 46 gives the personnel almost complete protection from field guns fired with percussion fuses. To make a parapet proof against rifle and macliine gun bullets and shrapnel balls, a thickness of 32 to 40 inches is sufficient. Thus behind a para])et 32 inches thick with an exterior slope of 1 on 5, the defender is practically altogether sheltered from rifle and machine gun fire and from projectiles fired with a service charge from long range pieces. Certain accidental shots on the crest alone can injure him. It is apparent that the profiles gi\-en in the manuals do not satisfy the above conditions in regard to the ex- terior slope. This is usually the natural slope of loose soil, or about 1 on 1. Every shell striking the exterior slope will penetrate the mass of the parapet and produce therein considerable effect. These profiles therefore ought to be modified in this regard and ought also be modified in other respects. Having determined the means of sheltering the defender from the projectile with a flat trajectory, the next consideration is to afford protection from high angle fire. This fire will be executed most frequently against the intrenchments by means of high explosive shells, and their powerful effects are well known. But, in order that these effects may be produced, it is necessary to hit the trenches, that is to say, the fire must be perfectly regu- lated. It is manifestly impracticable to try to shelter the men under great masses of earth in intrenchments on the field of battle. It can no longer be attempted even in the intrenchments constructed in a line of investment ; and, as a general thing, endeavors should only be made to render the adjustment of the enemy's fire as difficult as possible. 47 In consequence, the relief of the parapet should be re- duced as much as circumstances will permit, and every means possible should be employed to render the in- trenchments invisible at a distance (see paragra[)h 63). In order to reduce the chances of shrapnel or shell fragments entering the trench, it should be as narrow as practicable. The earth for the parapet can be obtained b}'- deepening the trench. It ma}' be necessary to sit close to the parapet in order to avoid the projectiles, and the parapet will afford protection in proportion to the steepness of its interior slope. It should be vertical if the earth will stand at that angle. Most soils will stand a short time in Aertical cut, and if there is time for the earth to break due to weathering, there should be time to revet it at the desired slope. A good intrenchment must therefore satisfy the fol- lowing conditions in regard to its profile : A relief as small as circumstances will permit; a para- ])et limited on the outside by a single gentle slope of about 1 on 6; a narrow trench, interior and reverse slopes as steep as practicable, replaced even, if possible, by vertical faces. It will be noticed that the thickness of the parapet, which had to be thought about when the ex- terior slope was steep, no longer comes into consideration when the latter is replaced by the prolongation of the superior slope. Furthermore, it is not even necessary to begin the exterior slope of 1 on 6 at the crest unless in exceptional cases when an increased relief to the parapet is necessary. Quite frequently it can be made witli a flat surface practically parallel to the ground from 32 to 40 inches in thickness. This will protect a little more against rifle bullets, and will not create any sensible dead angle in front. It w^ill also be more convenient for the de- 48 fender, who can more easily support his rifle. In order not to have a difference in lighting between this plat- form and the slope of 1 on 6, which might be seen at times, it ought always to be connected with the exterior slope by a curved surface. Profiles which satisfy the above conditions are shown in figs. 3-8 ; the trench walls are all shown vertical as ex- plained above. For the time necessary to construct these profiles see Chapter X. Fig. 3 shows a profile which may be used when the time available for intrenching is very limited ; it is too narrow for good communication, and for the comfort of the men occupying it. Fig. 4 shows the same profile widened to 3 feet, which is the minimum width ordin- arily allowed, affording fair communication, and allow- ing the men to sit with their backs to the parapet. The command in both these profiles is 1.5 feet, which is usu- ally the minimum that will allow all the foreground to be covered. (See par. 105.) Figs. 5 and 6 are triangular profiles with 2.5 and 4 feet command respectively ; in each the trench is deepened in the rear to afford covered communication. In fig. 6 a ditch is used to avoid excessive horizontal movement of the excavated earth. These profiles show the great in- crease in labor necessary to secure increased command and at the same time avoid making the parapet conspicu- ous. (See par. 106.) Figs. 7 and 8 show profiles of Japanese trenches in Manchuria. In both these, the earth not necessary for the parapet was thrown to the rear. (See par. 107.) Major Reichmann states : "The Russian troops were invariably intrenched and their trenches were heavily 49 manned ; as many men were generally put in the trenches as they would hold. "Wherever practicable the standing trench was em- ployed as being the best protection against shrapnel fire. The kneeling trench was not employed unless lack of time or the character of the ground made the standing trench impracticable. The lying-down trench I never saw. * ^ ^ "Tlie character of the shrapnel is such that the lying- down trench pro\-ides cover against it only, but not shelter. The man who lies down converts his vertical target into a horizontal one, but does not diminish it. and if his presence is known or suspected by the oppon- ent's artillery he will not derive much advantage from the lying-down trench. So far as I can see. the usefulness of this trench is limited to the infantry on the offensive, which has been checked and must hold out under the enemy's fire. Cases of this kind are most likely to occur in the infantry attack in battle. "According to the theory of battle the attacker should in the first place silence the opponent's artillery. He then covers the defenders' trenches with fire, and thus enables his own infantry to advance without undue loss to the position whence the final assault is to be launched. In order to be able to withstand this artiller}- fire and enable his infantry to rejuilse the attacker's infantrv, the gen- eral on the defensive must provide effective shelter for his men. The effect of shrapnel fire is so searching, so murderous, that this precaution is imperati\'e." Major Kuhn states : "In general the Japanese profiles were characterized by lower parapets, with flatter su- perior slopes, and wider trenches than the Russian works, a portion of the excavated material being thrown to the 50 reverse side of the trench. The form of parapet adopted by the Japanse lends itself better to concealment, but the width of trench renders it more exposed to shrapnel fire. The greater width of trench has for its object, of course, the securing" of lateral communication. ''A feature of all the more elaborate Japanese trenches was a small berm, about 10 inches below the crest, de- signed as an elbow rest and to give great steadiness to the rifle. This feature impressed me as possessing con- siderable merit. "Low, flat parapets lend themselves better lo conceal- ment, while deep narrow trenches furnish the best cover. Whether one form of profile is better than another will depend upon circumstances. For purely defensive pur- poses the deep narrow trench is unquestionably tlie best, but where offensive movements are contemplated a more open trench of the Japanese type is preferable,, not only because it affords good lateral communications and an easier exit, but because its more open construction is better suited to maintaining a proper temper in troops which are to assume the offensive. *Tn their lines north of Mukden near Chinchiatun the Japanese introduced ditches along several portions of the front. These ditches were located 20 to 30 feet in front of the fire trench and were flanked 1:)y field caponiers located at the salients or re-entrants and connected to the fire trench by a sunken and covered passageway. The ditches were about 6 feet deep, 5 feet wide at the bottom, with side slopes of 2 on 1 and 3 on 1." ( See fig. 2.) At Port Arthur the trench shown in profile, fig. 9, was constructed 700 to 800 yards in front of the main line. It was not connected with other trenches, its com- munication with the rear was very difficult, it had very ^t aridin^ Trer)ches. ^ {-4:t Fi^. 9. /Russian rre7?c/7 at Port /J r thur 5 O 5 (O (6 FEET Scale JH 53 little support from other sections, and yet, notwithstand- ing all that, it managed to hold out almost a month. Its length was about 600 yards and its garrison, one company of 200 men, or one man per 3 yards. Each man was pro- tected on the sides with sand bag traverses and provided with head cover. A small cave was made in the wall at the bottom of the trench for keeping a supply of cart- ridges. The parapet was of earth 21 feet high and 7 feet thick and well concealed with sod. (See par. 108.) 46. Some form of head cover should" be provided, otherwise the defenders would be absolutely prevented from manning the parapet for firing purposes, by a heavy fire of musketry and shrapnel. For different forms, see E. F. M., par. 13. A good loophole should not be visible; from a dis- tance, it should blend into the parapet, which can be se- cured by adding earth in front and at the sides ; the open- ing of the loophole should not project on the sky over the outline of the breastwork. Generally speaking, the construction and masking of loopholes constitutes a very delicate work requiring great attention. The opening should be masked. A notched parapet is shown in fig. 10, and the pro- tection afforded a man firing is indicated. (See par. 109.) In the Russo-Japanese War at Port Arthur, a loophole cover (a light splinter-proof over the loophole) was found necessary to protect men firing, from shrapnel. This is shown in fig. 9, and an enlarged section, in fig. 11. (See par. 110.) Loopholes should not be at intervals less than one yard, to avoid weakening the parapet. When the head cover is not considered advisable, a substitute consists in providing sand bags stored in the 54 trenches. When the moment for opening" fire arrives, each solcher can lay a sand bag npon the parapet, prac- tically parallel to the direction of his fire. This gives an improvised head cover which is movable and which has not served the enemy's artillery in discovering the work, and now plays its part in the protection by almost com- pletely sheltering the head of the marksman. Some bul- lets may go through it perhaps, but it will stop a great number to such an extent that the vulneral^le surface of the man behind it will be very materially reduced. General Ian Hamilton states : "From Majuba time onwards I have always held the opinion that loopholes (IouIdIc the value of any cover, and all I have seen since has tended to confirm me in this view. Even during an attack the soldier can usually find cover for his body, and if not, he can rapidly extemporize it with stones or spade work. Under such conditions he is at least on an equal footing with an adversary who has to show his head over the straight line of a conspicuous breastwork before he can fire. Indeed he is far less visible, and thus less vul- nerable to distant artillery fire. To give a defender that indisputable advantage which is necessary to counteract the depression of having to wait whilst the enemy is ad- vancing, he should be pro\ided with a loophole, or head cover of some sort. Then, and only then, will the aver- age soldier retain confidence enough to use cool, deliber- ate, aimed fire amidst the showers of shrapnel and rifle bullets which whistle and sing past his ears. Otherwise he fires hastily and fires high, the instinct of self-preserva- tion impelling him to 'loose off' as quickly as possible, and get his head those twelve inches lower which will give him. at least momentarily, immunity from deadly danger." 55 Major Knhn slates: "As wasJjobe expected, the ina- terigj_ ^amag e inflicted by artillery on field works proved a negligible quantity, but some form of head cover was show n -to b e ijecessai'yJto give protection and confidence to tJTg tro ops when long exp osedj^o shrapnel fire. "\\'hen loopholes were used in field works they were made most frequently of sand bags or sod. When ax-ail- able, brick and stone were also employed. "At Liaoyang and Haicheng the Japanese trenches had little mounds of mud on the superior slope. In the absence of more suitable material these mud mounds af- forded a simple and fairly effective form of head cover." 47. A background for the heads of the parapet de- fenders would usually be provided by the natural ground in rear, by placing the parapet somewhat forward of the crest of the hill. Where this cannot be done, it may be necessary to provide it artificiall}'. In order that high explosive shells may not injure the defenders who are manning a parapet or sitting close behind it. it is necessary that there should be nothing in rear to catch the shell and explode it or act as a stop-butt, for in this case the back-blast or all-around effect would cause loss. The ideal arrangement would be to have the parapet in such a position that all shells just missing the crest would pass clear away into space. But this could very seldom be arranged, as it would usually entail trac- ing the parapet on the sky line when viewed from the enemy's position, so that the defender's heads would be conspicuously visible. It should, however, always be ar- ranged so that -there is no steep rising ground or bank close behind the parapet. For this reason most redouts or forts are regular shell 56 traps because of the parados, designed to protect the de- fenders of the gorge of the redout from reverse fire. 48. Arrangements for Fire to the Rear. — In the present day regular closed redouts are not usuaily re- quired, so protection to the defenders of the gorge is un- necessary. If it is desired to provide a firing line facing towards the interior of the fortress, it should be at a distance off, and probably on the reverse slope of the hill, or in some other place hidden from the front. If a closed redout is constructed, its gorge trench should have a double parapet ; the front one, serving as a parados, should be kept low^ and used as a firing line to command the interior of the work, in case the enemy gets in over the front. If the trenches are in such a position that there is a field of fire to the rear, they may be arranged for fire in that direction. The profile shown in fig. 12 may be so arranged by loopholing the reverse parapet. 49. Overhead cover of some sort should always be provided unless the exigencies of time prevent it. It is not, however, necessary that this shelter should be of a ver}' massive or elaborate description. It is very doubt- ful whether it would ever be necessary to make the cover of a sufficient. strength to resist bombardment. It is evi- dent that if the shelter is made completely underground and the earth above it is made to exactly resemble the surrounding ground, it will be impossible to locate its position, or to drop successive shells upon it. The utmost it would have to fear would be a chance hit. Splinter-proofs should satisfy the following condi- tions : 1. They must not cause breaks in the firing crest, for they would then necessitate an increase in the linear 57 development of the trenches for a given number of marksmen, and consequently would increase the labor by a considerable per cent. 2. They must be capable of construction after the trenches are built, without requiring any considerable re- adjustment of the work already done. This condition will be very useful when it is not possible to determine upon the time available for fortifying a position, when there are not a sufficient number of workmen to make both parapets and shelters at the same time, and when it has not been possible to get together the necessary ma- terials for the building of these shelters at the moment when work on the trenches can be commenced. 3. They m us t perm j^the sheltered men to come out rapidly, in order to get to their fightTng posftions behind the firing crest. 4. They must not cause any projection above the parapet, which would immediately disclose its presence. The shelter may be small in area; it is only required to accommodate the men in the firing line, for the sup- ports should be in another shelter in rear. If time and materials do not admit of covered-in shelters being pro- vided, a deep, narrow trench will give fair security. If the earth admits, it may be recessed on the side next the enemy, as in the Boer trench (fig. 11, E. F. AL). Fig. 12 shows a form of splinter-proof which may be constructed after the trench is completed, and gives com- plete protection to men firing. (See par. 111.) In fig. 13 is shown a splinter-proof constructed in the trench shown in fig. 3, which fulfils the above condi- tions. Fig. 14 shows a splinter-proof which can be con- structed either during or after the construction of the 58 trench shown in fig. 3. By deepening the trench as shown by the dotted hnes, two ranks of men may be sheltered sitting, facing each other; see par. 112. (For other forms see fig. 10 and E. F. M. firs. 34-43.) When shelters are constructed immediately in rear of the works, in order to prevent their being hit by shots aimed at the firing trenches, they should be separated from their firing trench by at least three times the mean probable error of the pieces having the greatest error. This error may be assumed as about 50 yards for pieces in use today. Therefore shelters must be established at least 150 yards from the work, unless local conditions and the form of the terrain permit this distance to be reduced. But by judiciously placing the shelters a distance of even twice the probable error in rear of the firing crest ; that is, 100 yards, the probability of being struck by shots aimed at the crest will be very small. Another method often preferable, of guarding the splinter-proof against shots aimed at the trenches, con- sists in placing it a little to the rear and outside of the flanks. It is evident then, in this case, that if the neces- sary precautions are taken to render the shelters as in- visible as possible, they will not become the object of special fire, and they can be placed much less than 100 yards to the rear. In both cases it will become necessary to establish covered ways between the shelters and the trenches. This latter will most frequently be possible only in sieges. The thickness of overhead cover for splinter-proofs should be from six to eight inches of earth on a support of brush or poles strong enough to hold it up. For bomb- proofs a minimum thickness of six inches of timber and three feet of earth is necessary against field and siege 59 guns, or twelve inches of timber and six feet of earth against howitzers antl mortars of a heavy siege train. The essential thing is the thickness of the earth layer, while the beams serve only to support the earth. In determining the area of overhead cover to be pro- vided, allow six s(|nare feet per man for occupancy while on duty only, or twelve square feet per man for continu- ous occupancy, not of long duration. For long occupa- tion eighteen to twenty scjuare feet per man should be provided. 50. Lookouts. — In all firing trenches provided with overhead cover, some form of lookout must be provided to enable the occupants to keep informed concerning con- ditions and mox-ements in their immediate front. These lookouts will ordinarily be arranged in a manner similar to loopholes with the extra condition that they should give as extensive a view over the foreground as possible. Major Kuhn, in describing the Japanese lines north of Mukden, states: "No projections are allowed above the fire crest excepting only the lookout stations, which are located on the most commanding points a few yards in rear of the fire trench. These are made bombproof and kept "as low as possible consistent with having the sight- ing slit overlook the foreground." 51. Maga:;inc accoininodatioii is not necessary. Rifle ammunition is best placed in recesses distributed all along the front, close to the parapet, and these would be re- plenished frcMii an intermediate depot in rear of the works. Artillery ammunition will be stored near each gun emplacement. 52. The trenches and shelters should be in short lengths, particularly if oblique or enfilade fire is to be anticipated. This will facilitate their adaptation to the 60 ground. Lateral communication need not be sacrificed by this, as the trench, may continue round a piece of natural ground left as a traverse. If possible, the length of any distinct independent piece of trench should be such as to be suitable to be garrisoned by a distinct unit, such as a company, platoon, section or squad. 53. In locating a line of trench it is important : 1. To avoid a sky line. 2. To occupy the military crest or line in advance of it. 3. To preserve communication under cover with the rear. The selection of the exact position of infantry trenches, how far forward or backward, is a matter of considerable importance. If the defensive position is on a hill or ridge it will generally be difficult, if not impos- sible, to find any spot at or near the top where all the ground in front, both near and far, may be seen, except in a position greatly exposed to view and fire; especially that of the enemy's artillery located behind an opposite ridge. It may also often be difficult for the artillery of the defense to sweep the slopes in front of the trenches, without using direct fire in an exposed position. (See par. 18.) Often the best situation will be at the bottom of the hill slope, at or near its junction with the plain in front; from these a grazing fire can be brought over the plain, and trenches in such a position can probably be well con- cealed, and it may be difficult for the enemy's artillery to reach them. It may be advantageous to give two lines of trench, one low down the hill, as above, and another firing over it at the distant ground from the top of the hill. The lat- 61 ter may, if the top of the hill is wide enough, be drawn well back from the actual front crest of the hill, and this will generally assist invisibility (fig. 15). This retired position would have a further advantage in that its sup- ports could be kept close up in rear on the reverse slope of the hill, and the ground in front of the trenches could easily be swept by the artillery of the defense, located in a sheltered position behind a hill or ridge in rear. If there is timber near the top of the hill, the line may be located in it, so as to have a good field of fire and yet not be exposed to artillery fire directed at the front edge. (See par. 62.) 54. Field of Fire. — The question as to whether the trenches should be located so as to control the ground at long and mid range or at short range is important, and no single rule can be laid down for all cases, as the proper solution will depend not only upon the topography of the site, but also upon the relative proportions of artillery and infantry of the defense. I f it is impossible, on ac- count of accidents_ of the groun d, to keep the enemy under fire_irQmJ.400 yards in, it would beadvTsable to use the artillery so as to force an early deployment, and by lines of^skiimisher^ in advanced trenches, so situated that the men can be withdrawn without difficulty or without mask- ing the fire from the main position, delay his advance as much as possible, reserving the defense from mid range in for the main line. It will seldom happen that the entire field of fire to the limit of effective range can be completely swept from any position that can be selected. A position should be sought which reduces the dead spaces to a minimum in number and extent; and, if possible, advanced or auxiliary trenches should be located to sweep them. If the ground 62 is open to 1,000 yards or more, the long or mid range is more important than the short range, for an effective fire on the enemy while he is advancing from 1200_ta_200 yards range will almost certainly put him out ; or, if by any chance, he arrives at 200 yards in condition to keep on. little can be attained by holding him under fire from 200 yards in, and a retirement is in order, unless obstacles exist. In both cases, the advantage of dead space in the close foreground is more apparent than real, and the main trenches should not sacrifice command of more distant ground within effective range, in order to sweep the foreground. Such dead ground must be commanded at night or in thick weather by trenches detached or in flanking relation. On the contrary, if an enemy can approach under cover to mid range or less, there will scarcely be time to stop him by fire alone, and obstacles are desirable at close range, which must be commanded by fire. The trenches, in such cases, must be advanced to cover the close fore- ground, and if necessary another line in a different posi- tion established to sweep the more distant ground. 55. Coiniunnication zvith the Rear. — There is one considerable, difficulty attending the location of lines of parapet in a forward position low down a hillside, and that is in the provision of concealed means of access to them and of shelter for the supports. Where the works are hastily thrown up in anticipation of an early attack, it will be hardly possible to provide for these at all, and the use of works in such positions should in such circum- stances be avoided as far as possible. If the ridge is in- tersected by ravines or covered with growth through which men could move under cover, the trenches at the foot of the slope can be easily reinforced and should be constructed. 63 Where such works are absolutely necessary, and also in cases of other advanced isolated works where covered approaches cannot be constructed, the defenders, who must be in more than the usual streng-lh, must take their posts under cover of darkness, and must take with them food, water, and ammunition for the whole day ; for it will be impossible to reinforce them under fire or to re- lieve them except at night. Where, however, the works are constructed some time before an attack is expected, oblique approach trenches can often be provided, and this should be done wherever possible, but the configuration of the ground may some- times forbid it. Fig. 16 shows a typical arrangement of approaches and communications from the support to the firing trenches. Fig. 17 shows a section of com- municating trench ; if the enemy's fire is all from one side but one bank is needed. (See paragraph 113.) Their is little need for concealment of these com- municating trenches, for, if they are deep enough to pre- vent tlie enemy from seeing whether anybody is passing through them, he cannot afford to bombard them on the mere chance that there may be somebody there. It is only to prevent their betraying the position of the firing trenches that it is advisable to have them inconspicuous. They should be laid out so as to take advantage of all accidents of the ground, both to save labor and to secure invisibility. 56. Cover for Supports. — The provision of suitable cover for the supports is a most important matter. The best place is on the reverse slope of a steep hill. When good natural coveixloes not exist, it may be necessary to provide artificial splinter-proof sliclter'^, kept low and well 64 concealed, or even in extreme cases to provide bomb- proofs, but the latter v^ould only be necessary where the site was most exposed and unsuitable for defense. The supports must be protected against the fire of the artillery up to the moment of their intervention, and placed so that, if necessary, they can reinforce the firing line or make a movement to the front, without having to suffer greatly. This result will be obtained by placing them in the cover trenches constructed at least 100 yards in rear of the crest of fire, either opposite the inter- vals between the works or else upon the flanks ; and by placing part of these trenches prepared for firing, so that they can cover the intermediate terrain well with their fire without leaving the trenches; or by abandoning the trenches in order to make a move to the front. Under these conditions the reinforcement of the line of fire will be made, if there is occasion to make it, simply by pro- longation; whilst that of the counter attack, setting out from a point very close at hand, will very quickly leave the zone bombarded by the enemy's artilleiy after he ele- vates his fire, and will act with all the desirable sudden- ness. Depending upon the terrain and the tactical circum- stances, the cover trenches of the units in reserve can be formed either into a single line or in echelon, corre- sponding each to about one section. They should not be placed one behind another, as that would increase their chances of being hit. When they can be prepared with light splinter-proofs of the type mentioned in para- graph 49, two men per yard of length can easily be shel- tered. The development will be still less with the more elaborate type of splinter-proofs. Major Reichman states: "The shrapnel is a most ef- - n:o — -> Profile Fi^.jO E/evatior} Notched Parapet with Splinter -Proof . ,,^JJ?^^>//f//>//fi!. (''''-W/'^/////^ ^^Ao.» /.oophoJe Cove?' Scale g » 't 18 14 lr,ch«« Fig.lZ Spli Titer- Proof Zo%t Scale > :^iWMV.M. (-3;o ^. ,^ SpU77ter-Proof5 . ^. _ Trencties retired dr?d ,^dy<3r7ced Ir? fa/?fry Positions StiQwing coTTf mzinicatfor7s ^itf? supporfs 67 fectivc and deadly projectile, and in combination with its long- range, compels all to hng co\'er. The side that stands on_iIi£_defeniive_iiiust have very ^sjtibstantial cover if it wishes to^yoid murderous losses, and at the longer ranges with the steep angle of incidence of the shrapnel the reverse slopes of hills offer little protection. It is therefore necessary that not only the firing line on the front slopes but the reserves on the reverse slopes, be protected by suitable cover." 57. The drainage of defensive works that are to be occupied longer than a day is of great importance and should be provided for, as otherwise the trenches and works may be so flooded by storms as to become unten- able. The drainage problem is difficult in deep trenches ; pumping- may have to be resorted to, or seepage pits dug. All surface drainage into trenches should be cut off. 58. Tclcplionic couununication should, if possible, be provided between the positions of the supports and each of the principal infantry trenches or groups of trenches, and also to the post of the section commander in rear. (See paragraphs 13, 24 and 76.) 59. Obstacles. — With an open field of fire, en- trenched troops with magazine rifles and plenty of am- munition do not recjuire the aid of obstacles to enable them to stop the most determined attack. Still, they would always add considerably to the strength of a posi- tion, and there may be places where obstacles are re- quired; namely, where the work is retired behind the -military crest of a hill so that the field of fire is short, or to delay troops at certain points where a heavy fire can- not be brought to bear on them, such as at the passage of a bridge or ford, in a defile, etc. Obstacles are designed to protect the works from sur- 68 prise and to reduce the momentum of attack by breaking- up the enemy's formation, and holding him under the accurate fire of the defense. They shoukl be invisible from the direction of approach, should be difficult to de- stroy, and should afford no screen or cover to the enemy. Obstacles should be placed at such a distance in front of the parapet that shots directed against it will not se- riously injure them. The fire of guns is more efficacious against obstacles than that of howitzers and mortars; and their probable mean dispersion is about 30 yards. Consequently, obstacles ought to be established from 90 to 100 yards from the parapet, and never less than 60 yards, unless covered or screened. This distance between the trenches and obstacles which the effect of the artillery fire recjuires, is also de- manded by moral considerations. If the obstacles are placed too near the trenches the defender of the para- pet runs great risk of becoming demoralized by the ad- vance of the assailant, whom his fire cannot stop, even before the enemy reaches the obstacles. These obstruc- tions will then be useless. They should always be so placed as not to interfere with the execution of counter attacks. They should usually not be placed at a distance from the firing trench greater than 400 yards, in order that the defenders of the trench may not be under artil- lery fire when the attacking troops reach the obstacle. If on the line, they are in the ditch, if there is one, or are employed to close intervals, and are flanlced or en- filaded by adjacent works. The high wire entanglement is the most generally useful of all obstacles, because of its effectiveness, the rapidity of construction, the difficulty of removal, the comparatively slight injury from artillery fire, and its in- 69 dependence of local material supplies. In woorled coun- try abatis or slashings would generally be used. (See E. F. M.. paragraphs 49-59.) 60. Clearing the foreground in front of the infantry parapet is important, but of course it will generally be impossible to get rid of all the cover within effective range of modern rifles. As much as possible should, however, be done, beginning near the works and pro- ceeding outwards. If possible the clearance sliould ex- tend to at least 800 yards from the parapet. The demoli- tion of every house or village in front of the defender's works is not so important nowadays as it used to be; the attackers will not be able to use the buildings as posi- tions for their infantry, as a few rounds of high ex- plosive shell would bring them down in ruins on their oc- cupants. They should, however, be removed if conceal- ment could be obtained in rear of them for the attacker's columns. 61. HousCjS or znllagej_yvhich exist within a de- fensive line will seldom be of any use from a defensive point ofjview. If occupied they would offer most easy targets for concentrated artillery fire, and the destructive effect on buildings of mod ern high ex plosiv e sh ell is so great that^they-jazjoiild bring ruin on any jtraops within them. It would generally be safe to ignore them alto- gether, as the reasons which make them unsuitable for the defenders to occupy would also make them objects of little temptation to an attacker, who would similarly be unable to hold them under the defender's fire. If it were really necessary to deny to the attackers tlie ground occupied by buildings, it would be best to put the defend- ers in trenches outside, well clear of splinters or frag- ments of stone, but in a position to bring fire over the ap- 70 proaches to the buildings. In places, however, where artillery could not be brought to bear, a group of strong buildings could be easily made into a strong defensive position. Isolated walls or walled enclosures without roofs, if thick enough to resist rifle fire and shrapnel bul- lets, are useful, for they cannot be damaged except by a direct shell hit, and even then only a short length will be blown down. They afford, however, a good target. (See E. F. M., paragraphs 60-63.) 62. JVoods are not generally very useful under modern conditions. If it is known that the front edge is held, so good a target is afforded that a very heavy fire can be concentrated on it. The interior of a wood certainly gives concealment, but great labor is involved in preparing a defensive position there and forming a field of fire, obstacles, and communications. Such a po- sition gives no fire outside the wood to the front, unless the wood is on a steep slope ; in which case a line might be located in the wood and have a good field fire to the front. If a wood is in front of the defensive line, its rear edge should be entangled and positions taken up from which a fire can be brought to bear on troops issu- ing from it. Generally speaking, a wood in a defensive position is a source of weakhessV'aiicPvvorks~sliould be arranged if possible to bring a heavy^fire OA-er^ie ground in front of them so as to prevent the enemy from getting into them. It may sometimes be possible to have the front line of the woods, or a position just outside the front edge, prepared for defense, with the defending" troops kept concealed in rear, and only brought up when an infantry attack develops, and the enemy's artillery fire must to a considerable extent cease. Communica- tions will in such cases be necessarv. 71 63. Co)iccaliitcitt.—¥\Y(i, when its effect can not be seen or learned, is almost certain to be ineffective, and may be merely a waste of ammunition. If the target cannot be distinctly seen, it is correspondingly difficult to ascertain the eft'ect of fire upon it. Concealment, there- fore, offers greater protection than any other single fea- ture, and every effort should be made to obtain it. As a result there is no longer such a thing as a normal type of trench ; for the form which might be best suited to one locality, owing to color of soil, configuration of ground and character of vegetation, might be very con- spicuous and wholly inadmissible at another. Concealment will have to be secured in each case ac- cording to the conditions of the site at the time. It is obvious that a trench in a landscape of green would have to be differently treated from one at the same place in the late fall or early spring; the color of the earth might be very conspicuous against green, but difficult to see against the yellowish brown of the same vegetation when dead ; the similarity of color would be stronger still in a plowed field. One .of the best means of concealment is the suppres- sion of the exterior slope. With the profiles given in our manuals, especially when the slopes are carefully finished, the parapet is visible at a great distance by the simple difference in lighting of the exterior and tlie superior slopes, and of the adjacent terrain. With a verv gentle slo])e of 1 on 5. or better, 1 on 6, that is to sav. a con- tinuation of the superior slope, the difference in lighting between the two surfaces is suppressed, and furthermore, a surface is made, which, leaving the general surface of the earth with a very slight angle, has a luminous value api)roximately equal thereto. 72 Objects projected against the sky are much more distinctly seen than when viewed against a background, other conditions being equal, and any location which will bring the trenches or guns on the sky line should there- fore be avoided. It should be remembered, however, that the sky line varies according to the observer's posi- tion, and that the one of importance is that from the enemy's point of \'iew. A distant background tends to render a trench more conspicuous than one close at hand, and a trench blending with its immediate vicinity, may be readily recognized, if projected against the different shade or degree of color or different vegetable growth of a distant hill. Where the condition of securing a proper field of fire forces the trench into a location in which sky line or background tends to make it difficult of concealment, it may be rendered inconspicuous by an artificial background or a slight screen in front. It should always be borne in mind that a man, close to a screen of vegetable growth, can see what is on the other side better than a man much farther away; and that if he is immediately behind it, he may have almost an un- interrupted view, even though it be thick enough to form at a distance a nearly complete bar to vision. In con- structing artificial backgrounds or screens, care should be taken to have them appear as natural features of the landscape, otherwise they will simply serve as trench markers. Invisibility is ordinarily increased by keeping the parapet as low as possible. Every foot that the com- mand is increased makes it harder to conceal the earth thrown up. In endeavoring to keep the parapet low, great caution must be observed not to put it below the height demanded by a proper field of fire over the fore- 76 ground, and this can be determined only by putting tlie eye at the same height that the soldier's eye will be in firing. Invisibility is also increased by causing the parapet to blend in with the landscape as much as possible; this is effected by various means, such as avoiding all sharp angles, causing the ends of the parapet to fall away grad- ually and generally avoiding any sudden changes in direc- tion vertically, covering the earth thrown up, if conspicu- ous, wath material which will conceal its color and cause it to resemble immediate surroundings, etc. It is more important that the trench be screened from artilleryTire than from infantry fire, hence efforts should be made to render it inconspicuous from the position which will probably be occupied by the enemy's guns or observers. If there is opportunity, an officer should be sent to these points to find whether he can, with a field glass, readily see the trenches or not; and, if they are quite discerned, to make note of the features which ren- der them conspicuous, whether color, shape, projection against sky or other background, etc. It is more im- portant to conceal the trench against the enemy's artil- lery than against his infantry, because the artillery can bring a shower of projectiles upon it from such ranges that the infantry rifle is helpless in reply, while against infantry fire of the attack, which must be delivered in the open, the trench should have the advantage. If the trench can be made inconspicuous at both long and short ranges, so much the better ; but officers should remember that the appearance at 100 yards may be quite different from what it is at 500 or 1,000 yards, and that within 400 yards ap- pearance matters little, as the enemy in attack is then 74 loo close to change his formation to conform to what he may then see. Major Kuhn states : "At Nanshan the parapets of the Russian trenches were relatively high and prominent. In fact, the Russians made no attempt at concealing their trenches in their positions preceding the battle of Liao- yang, and their works were conspicuous on the bare hill- sides. Even at greater distances, the freshly turned earth and prominent profile of the parapet plainly marked their location. At Liaoyang and subsequently, attempts at concealment by covering the freshly turned earth with sod and by adopting flatter slopes for the parapet, became manifest. "When practicable the Japanese always employed ar- tificial concealment for their trenches, covering the freshly turned superior slope with millet straw, bean vines, or kaoling stalks gathered from adjacent fields, or even planting a row of kaoling stalks in an upright posi- tion. "In the matter of concealing their works the Japanese took infinitely more pains and displayed a far greater skill than the Russians." Major Judson states : "Thus far I have dwelt upon the principle of dispersal. (See paragraph 13.) The other principle emphasized in this war was, of course, concealment. By every artful device the position of the defensive units must be kept from the enemy. The works must be of slight profile or mainly sunken. Much earth must be carefully wasted out of sight of the enemy. New earth within range of his vision must be sodded, or planted with stubble, to resemble neighboring areas. Ar- tillery positions must be located in rear of crests, villages 75 or woods. As a rule, rather tlian as an exception, artil- lery must fire over infantry. "To secure concealment and a proper location and dispersal of field works, obviously no special rules can be laid down. In each case what is required is an appli- cation of a trained common sense to the particular prob- lem offered by the terrain." 64. Diuiuiiy TrciicJirs or Parapets. — In case con- cealment of the general position is not possible, decep- tion must take its place. The trenches actually occupied must be so arranged as to afford concealment of the in- dividual man. and dummy tr^nchesr pwrposely made easily visible, may be arranged to draw the enemy's fire. Dtmimv trenches should, if practicable, have head cover, not only to make them more conspicuous, but also to make it more difficult to discover whether they are occupied or not. They are better above and behind the occupied trenches, if the lay of the ground permits. The enemv will observe that fire comes from the direction of the dummies and will conclude that it comes from them. Fire directed on the dummies will pass o^•er the heads of the defenders, a condition preferable to shots falling short, which would be the result of dummies in front of the occupied trenches. It is obvious that dummy trenches should be placed at such distance from the real trenches as not to bring the latter within the fire which they may attract. The Russians in Manchuria in some instances made a line by turning two or three furrows with a pl(jw which looked at a distance like the parapet of a trench ; and where they covered these furrows with grass, which soon dried, the effect of an imperfect concealment was strong. 76 CHAPTER V. Artillery Positions. 65. Low commands and inconspicuousness are to be sought for in the location of artillery emplacements, and they must be suitable for pieces on traveling mountings. (See paragraph 18.) Concealment of position is most desirable, whether artificial or natural cover is used, therefore sky line crests without cover are generally forbidden. It is quite as bad, if not worse, to take position on the reverse slope, where an enemy can easily range to the top, and then proceed to sweep the slope beyond. Without making the mistake of moving too far back, it is nevertheless ad- visable to make it from 100 to 300 yards, the ideal posi- tion being behind a crest of another similar height some distance in rear. The enemy would naturally be deceived as to the result of his shots going behind the first crest. To be sure artilley creates so-called "dead spaces" in taking such positions, but they must be cross- fired by units dispersed elsewhere. An intelligent dis- persion of the units, moreover, diminishes the enemy's fire and increases his difficulties of adjustment. (Sec paragraph 15.) In taking position behind a crest, a defilade of 1 5 feet is necessary for the concealment of the gun flnsli. The maximum effective ranges of field and siege artillery may be taken as follows : 3-inch field gun 6,500 yards 4.7-inch siege gun 7,600 yards 6-inch siege howitzer 7,600 yards 6-inch siege mortar 5, 500 yards 77 Major Kuhn states: "At Port Artlnir the Russians made the mistake of placing- batteries upon the highest and most conspicuous places, which became ensy marks for the Japanese batteries skilfully located in the in- equalities of the floor of the valley fronting- the Russian hills. In the later stages of the siege the Russians be- came wiser and some of their later batteries were most skilfully located, depending upon indirect fire, which latter can now be very well controlled and directed." 66. Form of Emplacement. — Na £orm ai^iege bat- tery will give protection from howitzer or mortar shells ; all that can be don^is to surround tlie_ gun platforms with splinter-proof walls to keep out frao-ments of shells which burst outside the emplacement. (See figure 118, E. F. M.) If the battery is in so retired a position, or so well concealed by intervening high ground, woods, etc.. that it cannot be seen from any part of th.e besieger's position, and observation of fire on it is impossil)le, then it is hardly necessary to have even splinter-proof walls, for a shell could only be dropped in the neighborhood of the emplacement by chance. If, on the other hand, the em- placement was anywhere visible, these walls would form too conspicuous a target. Emplacenienls^for direct_^re_glms^_wl^ich^^^^ be in_positions visible _to the^ ene my, would have to be con- cealed by^ sinking them into the ground, and having a background of trees or rising ground in rear. Iimsi- bility for sucli pieces is a matter of supreme importance, provided, of course, that range and field of fire are not sacrificed. Where the emplacements are liable to shrapnel fire, some form of cover for the detachments should be pro- 78 vided. This may, in the case of field defenses, consist of two deep pits close against the front parapet, one on each side of the gun, similar in principle to those in the ordinary type of field gun emplacement, but larger and deeper. (See figure 18.) Or overhead splinter-proof cover may be provided at the sides of the emplacements, or in the traverse, where such exists, between a pair of emplacements. 67. Positions for Liglif Guns. — :It would not as a rule be necessary to provide any works for the light rapid-fire armament or for the field guns. The essence of the employment of pieces of this nature is surprise and mobility, so that there should be nothing that will mark the positions from which they will open fire. If any form of protection is required, field q}aulments can be made when wanted. Guns firing by indirect fire will be behind natural screens, such as a hill, woods, etc., and usually will not need a parapet for protection. If by any chance the enemy should ascertain their position closely enough to make it uncomfortable or dangerous, they can ordinarily be shifted to some other place without detriment to their own fire. When engaged wTdi_direct fire, guiis^^ven though provided with shields, will need some screen or protec- tion. When the ground is soft and no naturaFcover ex- ists, guns are best protected by being sunk in pits or placed behind epaulments. The smallest mound in front of a gun will stop the bullets which could strike the gun crew in great numbers, by ricocheting under the shields. A larger parapet could almost completely place the ar- tillery under shelter from any percussive fire that the enemy would try against it. Moreover, in doing this the 79 artillery will not lose any of its mobility if it is well un- derstood that it must not consider itself as any more anchored to an artificial cover than it would be to a nat- ural one, which it certainly would not hesitate to make use of on such an occasion. Figure 18 shows a type of gun pit with the caisson body alongside the gun. The pits on each side may be provided with splinter-proof cover of the type shown in figure 12, if time permits. (See paragraphs 111 and 114.) Figure 19 shows a section through a gun pit for direct fire behind the crest of a hill. Figure 20 is a sec- tion through a gun pit for indirect fire. 68. Indirect Fire. — The distance that field guns us- ing indirect fire can take position below the crest of a hill is shown approximately in the following table : Ranges At 50 yds. 75 yds. 100 yds. 200 yds. 300 yds. 500 yds Yards Feet Feet Feet Feet Feet Feet lOOO 10 13 16 1500 10 19 26 38 2000 II 15 29 41 66 2500 10 16 21 40 58 3000 13 30 27 53 77 3500 17 25 33 66 4000 21 31 41 The following table will also assist in the location of field guns for indirect fire, and in determining the pro- tection afforded by reverse slopes to supports and re- serves : 80 ANGLES AND SLOPES OF DEPARTURE AND FALL OF SHRAPNEL. From Field Gtins. Ranges Departure Fall Yards Angle Slope Angle Slope 500 o°32' 1 TT5 o°35' 1 TC5 1000 i°ii' 1 5W l°2Y 1 1500 i°59' ] 25 2°38' 1 31 2000 2°sY ^V 4°o8^ 1 2500 4°02' t\ 5°49^ l^TT 3000 5°I2^ 1 TT 7°4i' 1 7.5 3500 6°2g^ 1 9°44^ 1 6 4000 i°W T^o I2°03' i 4500 9°28' i I4°37^ i 5000 II°IO^ i i7°26^ ^^.^ 5500 i3°oi' 1 20°29^ ^S 6000 I5°02^ \ 23°4i' i.^ 6500 I7°i3^ i-z 2 7°07^ i.^ The dispersion due to the explosion of the shrapnel shell increases the angle of fall of some of the bullets at 3,000 yards to about 18°, or 1 on 3. 69. Expense magazines for at least two days' sup- ply of ammunition are required in the neighborhood of each battery or group of emplacements. They should generally be on the flank of the battery, conveniently close, and connected by a trench to give covered approach. Recesses or benches for a few rounds of ammunition should be provided in each emplacement. 70. Means of access to the emplacements, to enable the pieces to be brought in or taken out, is very neces- sar\\ 71. Every battery or group of emplacements re- quires an observing station, which should be on com- 81 . niandjng: gTjpimd ffihenc£__all objects to be aimed at can be seen. They need not be- neaT_the_battery i f telephonic communication is provided. They should be as incon- spicuous as possible. A type used at Port Arthur is shown in figure 21. (See paragraph 115.) 72. Captive Balloons. — In case there are many of the enemy's batten.^ positions which cannot be seen from any of the sites available for observing stations, it may sometimes be possible to make use of captive balloons. (Sec paragraph 6.) 7Z. Eniplaccincnt for Machine Guns. — In the Japanese lines north of Mukden, mftebine guns emplace- ments were introduced along the parapet, their dimen- sions being 8 feet wide by 10 feet deep by 3 feet 6 inches high, with splinter-proof cover about 18 inches thick. An emplacement for two machine guns is shown in figure 22. When there is time, splinter-proof cover of the type shown in figure 12 may be added. Loopholes should usually be provided, and in case they limit the sector of fire too much, provision can be made for raising the guns to fire over the crest by means of sand bags stored in the trench. It is usually best to emplace two gunsjogether. (See paragraph 116.) 'JU^XWJ" v--- 12:0 - - 1 Plan (-3,oy QuTi -Pit SQctiorj C-D Section A-B r,j . c- ■ Russia r? Obserya?c Statioti P/s/f of Framt.no ^ frl.o) '. < ',1 1 n 1 1 n F-- li^ - H - .40 -« B 'D Plan Fig 22 Emplacement for Z Mac/jure Guns 85 CHAPTER VI. Auxiliary Means of Defense. 74. Electric searchlights will play a most useful part in defense operations of the future. Not only will they be a protection against night attacks, but also by their use, sapping or the execution of trench work by the enemy at night, at short and medium ranges, should be rendered impossible. They would be particularly use- ful in conjunction with light rapid-lire guns or pom- poms, or with machine guns, as with such weapons a heavy fire could be immediately developed on the object illuminated by the beam. The position of the beam in relation to the guns should be well to one side, for the best position for seeing illuminated objects is for the observer or gun-layer to have his line of sight more or less at right angles to the beam. It would be much bet- ter if the lights were not in fixed emplacements, as this would tie them to one spot; moreover, the emplacements would be conspicuous, and would be seen by day and wrecked. They should, therefore, if possible, be on traveling mountings, so as to be used from any infantry parapet or from the open. It is very difficult to hit a searchlight at night, owing to the impossibilitv of telling the range or observing the fire. If in addition, its posi- tion is constantly varying it would be much more dit- ficult to hit. 75. Interior Coviiiiuiiications. — The most important features of a fortress, or great defensive position, are the interior communications, and these should be the first of 86 the -works commenced in preparing a place of defense. In laying out the communications, regard must be had to the probable tactical organization of the defending force. It is desirable to have a road or roads from the headquarters of each section to the different main sup- porting points in that section, also a road from the town or general headquarters— that is to say, from the main supply and ordnance depots — to each sectional headquar- ters. In addition to these radial roads there must be a road or railroad all around the circumference of the posi- tion in the rear of the works. It is most necessary that the communications, particularly the circumferential ones, should be screened from the enemy's view. The movement of troops being the principal element of success, the communications, and especially those which must assure the execution of counter attacks or of offensive returns, have a prime importance. These lines of communication should be so placed as to be defiladed as far as possible, and so that they can be utilized during the whole course of the combat. 76. Telegraphic and Telephonic ComiiiiDiicatioii should be provided between all parts of the position; that is, from the fortress headquarters to each sectional headquarters, and thence to each important work or .group of works in the front line, and also to the artillery commander's posts. (See paragraphs 13 and 58.) 77. The water supply of a fortress is a most im- portant matter. It is obviously necessary that the place should not be dependent for this essential requirement upon an outside source. If its supply is by means of a conduit or pipe from a distance it is extremely possible that the besiegers will find and sever it. It is most neces- sary, therefore, that for war times, at all events, it should be possible to obtain a sufficient supply for the garrison and the civil population from sources within the defended area ; that is to say, from wells. A considerable economy can generally be effected by restricting the use of the pure water to drinking and cooking only, and there will usually be streams or rivers whence water for washing and cleaning can be obtained. If the only supply is from a river, it will be necessary to take steps to sterilize the water by boiling or otherwise, before it is issued to the troops for drinking. CHAPTER VII. Strength of Garrison. 78. The following considerations will have to be taken into account in detcnniniiig flic nuinhcr of men per yard necessary for an efficient defense : 1. The enemy's strength and armament. 2. Whether the position is circular or crescent shaped, so that reinforcements from the center can be rapidly sent to any desired point. Or if it forms a long line with slightly or no refused flanks, and if so, whether means, such as railways or good, con- cealed roads, exist by which reinforcements may be despatched. 3. Nature of the ground and artificial improve- ments; that is, if good cover is obtainable, if good communications exist, if the position is hastily in- trenched, or deliberately prepared for defense. 4. Character of defense ; that is. whether or not an offensive return is contemplated, and length of time the defense is to be maintained. 79. When a force is suddenly compelled to occupy a defensive position, with opportunity to make only the most hastv form of intrenchments, no fixed or even ap- proximate rule for determining the number of men per yard of front, is possible. The number per yard of front held at the commencement of the engagement would at times be greater than in the attack, as in the defense much greater depth of formation is necessary, and the re- serve bears a larger proportion to the whole force. _Thus three or four men per yard of front might be required. 89 80. When from tivelve to twenty-four ivorking hot4rs_w^^ht available for preparing a position for de- fense and no offensive return is contemplated, the num- ber of men per yard of front can be considerably reduced. 81. For positions elaborately fortified, having a cir- cular form, the number of men per yard could be very small, but as such positions would only be prepared where a continued defense was required, an increase in the num- ber of men per yard of front would be necessary to en- able casualties to be replaced. 82. In estimating the strength of garrison necessary for a carefully prepared defensive position, the best meth- od is to begin with the infantry, taking each section of the defensive area separately. The garrison of the works can be calculated with fair accuracy by measuring the actual length of the lines of infantry parapet, and allow not less than two men for each yard. Of this number about one-fourth should usually be in the supports and one-half in the section reserve. (See paragraph 13.) 83. The strength of the artillery may be estimated at thirty men per medium and heavy gun (three reliefs of ten) and eighteen men per light rapid-fire gun. If available, some field artillery with the section reserves will often be useful. The engineers should, if possible, be not less than one-twentieth of the strength of the in- fantry. 84. The strength of the general reserve would de- pend mainly on the facilities that are likely to be obtained for active measures. It is desirable to have it equal in strength to the total of the section garrisons; and, in any case if possible, not below half that strength. Mounted troops and field artillery would be usefully employed with this reserve if the defended area is a large one. 90 85. The following examples serve to show to what extent local conditions govern each particular case : At Plevna in 1877, where all the defenses were con- structed after the first Russian attack, the Turkish garri- son during the investment numbered 1,875 men per mile of perimeter of defense, or about one per yard. The place was held for five months and resisted all the Rus- sian attacks. At San Juan, Cuba, on July 1, 1898, the Spanish force of 1,197 men held a line about one and one-half miles long, of no great natural strength, and not care- fully prepared for defense, nearly all day, against the American force of 8,412 men; and inflicted a loss of 1,156 in killed and wounded. At Nanshan Hill in the Russo-Japanese War, the Rus- sian force of 18,000 men and 55 guns held the position for a day against the Japanese force of 42,000 men and 216 guns. The position was an ideal one for defense, being a hill 400 feet high, .which rose in the midst of a peninsula only two miles wide. It had been carefully prepared for defense. The actual garrison of the hill was only one regiment. Two assaults were repulsed and the third succeeded because the Russians had not ex- tended their lines of obstacles far enough into the sea, and did not bring up their reserves. At Port Arthur in 1904, there were 4,755 men con- centrated along the assailed front of two and one-third miles, and 7,730 men on the unassailed front of ten and two-thirds miles. The reserve of the attacked front con- sisted of 406 men; the reserve of the unattacked front of 496 men, and the general reserve of 510 men. Con- 91 sequently there were 2.038 men per mile on the attacked front, or 1.16 per yard. On the unattacked fronts there were 725 men per mile, or 0.41 per yard. (See the last part of paragraph 45.) 92 CHAPTER VIII. Defense of Small Isolated Posts Occupied by Detachments. 86. The foregoing has dealt mainly with the ca'se of a fortified position, held by at least an independent bri- gade, and liable to be attacked in force; a situation, in fact, which would probably be met with at points of stra- tegical importance. 87. At places where only a small force would be available for the defense, certain modifications would be necessary. In such a case so extended a line could not be taken up, so it would be impossible to have the de- fensive line so far out as to keep the enemy beyond bom- barding range of the town, and the supporting points would probably be closer together. The general prin- ciples and methods of defense would, however, be sim- ilar to those already described, subject to such modifica- tions as the altered conditions would require. 88. The case would be different when the position was quite a small one to be held by a small isolated de- tachment, as might exist for the defense of a bridge, or a post on a line of communications, on which an attack in great force or a very prolonged siege was not antici- pated. In such a case a widely extendedTiJOsTTion, made up of supporting points at intervals, would be impos- sible. The smalhiess of the defending force would neces- sitate its remaining more or less concentrated. 89. Instead of providing a continuous redout or fort, it would be better to construct simple trenches or 93 para^ets^'m such a manner as to in^rfere as little as pos- sible with the natural appearance of the gfotind ; in fact, to rely on skilful treatment of the natural features of the position selected. 90. An isolated position of this nature would have to be prepared for aU-aromid oftac^y~^o~^^eme of the trenches and emplacements would be required to face to the rear, and care would have to be taken to avoid the possibility of receiving fire in reverse. Shelters for the reserves would be necesary in some central part of the position, and this should be boJiib-proof if possible, and in any case well concealed. Shelters for storage of sup- plies, ammunition, etc., would be required, and the im- portant question of water supply must not be overlooked. 91. The position selected for defense would not in such a case necessarily contain within itself the object to he defended. It would hardly ever be possible to find a position that could be defended by a small force immedi- ately round the object, if the latter were a bridge, rail- way station, or place of that nature; it would usually be sufificient if the position commanded the object and the approaches at short ranges. Sometimes it might be 'necessary to make the defenses in the form of two posi- tions supporting each other, and both commanding the object. 92. // the enemy is uncivilized or unprovided zvith artillery it is evidently unnecessary to employ the elab- orate methods necessary against civilized enemies. Pro- tection against rifle bullets is easily obtained, and neither concealment nor overhead cover are in such cases neces- sary. Blockhouses and villages or strong buildings make good defensible positions in these cases. For the methods 94 of preparing these see E. F. M., paragraphs 46, 61, 62 and 63. For a fortified post in a savage country a material obstacle is generally essential; so if the work itself does not provide one in the form of a wall or stockade, a strong, independent one in the shape of barbed wire en- tanglements or abatis should be provided. A clear field of fire is, of course, imperative, and flank defense should be provided, dead angles being inadmissible. Every fort of this nature should be self-contained; that is, should contain room for storage of supplies and ammunition, and should be possessed of its own water supply. 95 CHAPTER IX. Fortifications on the Offensive. 93. Fortified positions will be used in the field by armies on the offensive as well as on the defensive. The fortifications erected by the former will generally be of a hasty and slight character, thrown up by its outposts for protection against sudden attack, and for the purpose of holding the ground then occupied, but soon to be aban- doned in an advance movement. Those used by the latter will often be of the character just described, if the army is advancing or retreating, but in retreat it may also make use of positions carefully selected and strongly fortified, previous to the arrival of the main body of the army. 94. Fortifications will also be used by both armies on the battlefield \.o enable the lines tohold the positions they may occupy at the time, and such works will be thrown up after the beginning of the engagement. The same body of troops may create two or more lines of trenches or breastworks in a single day as it advances or falls back; the works must necessarily be of slight strength at first, but if the troops remain undisturbed for a few hours the line may become strong. This method of fortification was carried to a highei^ degree of per- fection in the Uivil War of 1861 to 1865 than it ever was before or has been since; as owing to the length of that conflict, the soldiers learned to appreciate the value of the spade to an extent that no amount of peace instruc- tion or drill can equal. The battle of the Wilderness is a good illustration of this fortification of the battlefield; 96 that conflict, which began by both armies assuming the aggressive, terminated by each being so strongly in- trenched that the other did not consider it prndent ta continue the attack. 95. In the face of an active defense, muhiplying its counter attacks and offensive returns, tlie attack will have great difficulty in maintaining itself in the conquered positions where it will nearly always, immediately after the capture, be compelled to take up the defensive atti- tude for a certain length of time. It must therefore have recourse, like the defense, to the resources of fortifica- tion, in preparing the boundaries of woods and villages, in making the intrenchments face the other way, or in building new ones, and in doing these things as rapidly as possible. In darkness or fog an advance may be made close up to the defensive line and a good intrenched position taken up. . 96. The location of the fortifications of this char- acter upon the battlefield will be determined by the posi- tion of the line. Troops in contact with the enemy can not remain stationary without cover. An advance can be made in the open, utilizing such natural cover as may exist at the locality. A withdrawal in the open is more difficult than the advance; and, with modern weapons, is more destructive, unless the attention of the enemy can be retained by other covering bodies of troops. To re- main without cover in the open is annihilation. An ad- vancing force, if it cannot push its way further, must obtain cover where it is or go back. The former will be less costly, and if the line cannot be reinforced, it will be best to get such cover as it can manage to throw up, and-liolcLon until dark. What is called the skirmisher's 97 irejich, .or.pit, can be excavated by a soldier while j .ving- down, and will be w hat he will try to secure after h aving heaped^a ipound of earth^or se gured a ny other cover in front__af-hi& heatUin_.the most expeditions rnanner pos- sible. (See paragraph 9 and figures 3 and 4, E. F. M.) Similarly a line that is being pushed slowly back will en- deavor to intrench itself at the first opportunity, and maintain its ground. 97. Such_trenches or cover are wholly tactical ; they ca nnot be pre pared in advance, for they depend upon the position of the troops and must conform to that con.di- tion. They must be constructed by the troops; and that one of the opposing forces, which has its officers l^est able to advantageously locate the trenches within the lim- its allowed, its men trained to realize the importance of cover and provided with means for doing the work in the shortest time, will have a great advantage over an army deficient in any one of these respects. Such constructions will ordinarily form_iiit^enohed lines rather than fortified positions, although the latter may be developed from them. Major Kuhn states : "In their attacks on the Rus- sian positions, the Japanese firing lines, lines of support^ and reserves frequently constructed hasty intrenchmcnts as they advanced over the fire zone. These intrench- ments were of the simplest form to give cover quickly, being thrown up with the portable_intr£nching tool car- ried by the sokliers, and giving cover lying down or kneeling. They served to cover the s uccessive a dvances of the infantry line, being occu pied m turn by the firing- line, lines oTsupport, and reserves, and being continually strengthened by the rearmost lines." 98 Major Morrison states : "Around Liaoyang hasty intrenchments were frequently used by the Japanese. Troops pushed forward against the Russian works, when checked, threw up hasty cover, sometimes kneehng or lying, but more generally merely head cover. This con- sisted simply in digging and throwing the dirt to the front, height and thickness depending on the circum- stances of the case. "At this place I saw cover constructed for the reserve. It consisted of parallel mounds of earth thrown up about 20 paces apart and about 3 feet high, including the trench, behind which the troops could sit. I was told it was ef- fective cover for shrapnel. They were out of range of infantry fire. "In the advances on the Sha River hasty intrench- ments were in constant use. They presented no new fea- tures. "One trench constructed by the Russians and cap- tured by the Japanese was converted to their own_Lise by the latter by digging a trench on the reverse side. "As far as I could observe or find out by questioning, the hasty cover, either kneeling or standing, was safe cover from shrapnel while the men remained close be- hind it." General Kuropatkin in his "Study of Japanese Tac- tics," states : "We once had an opportunity of closely watching an advance made by the Japanese against the front of the position held by the Thirty-eighth Alrofski Infantry Regiment. "They attacked in widely extended skirmishing order. The firing line advanced at the double for a short dis- tance, lay dowjvand comrnenced to dig. Notwithstand- ing our extremely heavy fire, they again doubled for- 99 ward, giving" up their half constructed trenches, and be- gan to dig new ones. The supports then doubled for- ward and occupied the first trenches and completed them. When the firing line advanced from the second line of trenches, these were occupied by the supports, and the reserves then moved up into the first line of trench. The advance continued by successive rushes in this manner." 98. Siege Operations. — Any field army may be called upon to attack fortified places, and such operations may include all the refinements of regular siege opera- tions. (For the details of siege operations see para- graphs 65-118, E. F. M.) 100 CHAPTER X. Calculation of Men and Time Required to Execute Defensive Works. 99. Tasks. — The capacity of the average untrained man for continuous cHgg-ing does not much exceed 80 cubic feet for easy soil, 60 cubic feet for medium, and 40 cubic feet for hard soil. He will do three-eights of this in the first hour, five-eights in the first two hours, and the other three-eights in the other two hours. In addi- tion to the fact that he works but a little over half as fast in the second two hours, four hours' work will leave him unfit for fighting or marching, while after two hours' work he should be able to do either. The quantity of work assigned to each relief should be that which can probably be done in two hours, and the relief is required to finish it and no more, whether it takes less or more time. For the first work, the soil is apt to be loose and the lift less, so that a slightly greater task should be given to the first relief than to the second. Assuming men at five foot intervals and neglecting fractions, the number of hour's work required to throw up a parapet is the section of the parapet in square feet divided by five for eas}-, four for medium, and two and one-half for hard soil. When men and tools are plenty and it is desirable to complete the work promptly, the tasks may be made four feet long, but at night five foot intervals are neces- sary to prevent interference or possible injury to the men. (See E. F. M., paragraphs 37-43.) 100. Double Gangs. — When men are plenty, tools 101 are scarce, or time presses, a task may be completed in about two-thirds of the ordinary time by detaihng two men at each set of tools. The two gangs change off at frequent intervals and the men work as rapidly as pos- sible. 101. Where traction ditchers are available, as in many cities and towns, they may often be advantageously used to construct infantry trenches. Some forms can dig a ditch thirty inches wide and three feet deep at the rate of one yard per minuted 102. The Fort Riley redout (figure 205, E. F. M.) for one battalion could be constructed by its garrison in six days of ten hours. If plows and scrapers were used in addition to the men, it would require about four days. (See paragraph 42.) 103. The Russian redout (figure_l} for one com- pany could be constructed by its garrison in about six hours in ordinary soil. (See paragraph 42.) 104. The Japanese redout (figure 2) for one bat- talion could be constructed by its garrison in two days of ten hours. (See paragraph 42.) 105. The profile shown in figure 3 has a trench area of cross section of 6 square feet, and applying the approximate rule in paragraph 99, could be constructed in from one to two hours. The profile shown in figure 4 with a trench area of 9 square feet would require from two to three hours. (See paragraph 45.) 106. The triangular profile shown in figure 5 with a parapet area of 22 square feet could be constructed in from two to four hours with two men per 4 feet of length. The triangular profile shown in figure 6, with a parapet area of 44 square feet, could be constructed 102 in from four to eight hours, and would require three men per 4 feet of length, on account of the excessive hori- zontal movement of earth necessary. For the additional men necessary for the construction of the revetment, see paragraph 117. With a scraper and plow 20 to 30 feet of parapet could be constructed per day of eight hours. (See paragraph 45.) 107. The Japanese profile shown in figure 7 has a trench area of 20 square feet and could be constructed in from four to eight hours. That shown in figure 8 has a trench area of 28 square feet and could be constructed in from six to eleven hours. (See paragraph 45.) In both these profiles two men per 5 feet of length could be worked and the time could be halved. For the addi- tional men necessary for the construction of the revet- ment, see paragraph 117. 108. The Russian profile shown in figure 9 has a trench area of 18 square feet and could be excavated in from four to eight hours. The loopholes, loophole covers and sand-bag traverses would require about four hours additional. This trench was actually constructed in two nights. (See paragraph 45.) 109. The profile shown in figure 10 has a trench area of 16.5 square feet and could be excavated in from four to eight hours. The construction of the splinter- proof would require an extra man per 5 foot task. (See paragraphs 46 and 49.) 110. The loophole cover, figure 11. could be con- structed in half an hour by one man if the materials were convenient. (See paragraph 46.) 111. The earthwork of the ])rofile sliown in figure 12 could be executed in from two to three liours. The 103 loojjholes and overhead cover would require two hours additional. (See paragraph 49.) 112. The splinter-proofs shown in figures 13 and 14 would require from one to two hours for construction with two men per 5-foot task, if the materials were at hand. ( See paragraph 49. ) 113. The communicating trench, figure 17, has an area of 12 square feet and could be constructed in from two to four hours. With a width of 2 feet it would have an area of 8 square feet and would require from one and one-half to three hours. (See paragraph 55.) 114. The gun pit, figure 18, has a total volume of excavation of 330 cubic feet and could be constructed by twelve men in from one to two hours. (See paragraph 67.) 115. The Russian observing station, figure 21, could be constructed by ten men in eight hours. (See para- graph 71.) 116. The emplacement for two machine guns, figure 22, has a total volume of excavation of 340 cubic feet and could be constructed by eight men in from one and one- half to four hours. (See paragraph 73.) 104 117. The following table gives the time required to execute different kinds of work in hours of one man: Description of Work. Figure in En- gineer Field Manual, Parts Work done by one man in one hour Remarks. Cutting brushwood 6 years old. 15 sq. yds. Cutting only. Felling trees with axe, untrained men : ' 4 in. diameter . . . No. 30 10 6 3 2 0.6 6 in. diameter . . . 9 in. diameter. . . . 2 men to each ' tree. 12 in. diameter. . . . 1 8 in. diameter. . . . 30 in. diameter. . . . Abatis, small trees close ^ at hand, 10 yds. wide 90 0.25 yd. Slashing, 10 yds. wide . Ql I yd. At edge of Low wire entangle- woods, etc. ment, 10 yds. wide. . I yd. High wire entangle- ment, 10 yds. wide. . . lOI 0.3 yd. Military pits, 5 rows. 104 0.5 yd. Walls, loopholes cut with chisels log No. 4 I man to each. Walls, notches at top loS No. 20 I man to each. Gabions 64 No. 0.3 3 men to each. Fascines, 18 ft. 55 No. 0.2 5 men to each. Hurdles, 6 ft. by 2 ft. 9 in 61 No. 0. 2 3 men Sand bag revetment. . . 53 8.8 sq. ft. 5 men Sod revetment 54 5 sq. ft. Continuous hurdle revetment 2 sq. yds Gabion revetment 65 59 34 Executed at Fascine revetment. . . same time as Overhead cover Siege gun emplace- 4 sq. ft. earthwork. Not including earthwork. ment 118 0.005 70 men, 10 hrs. 105 CHAPTER XI. Field Problems in Fortification. 118. Field Problems in Fortification are intended to take up the details of the phase of terrain exercises, such as are given in the Military Art Department, following the issuing of the order for taking up a defensive posi- tion. 119. The course in Field Problems in Fortification for the Staff Class consisted of eight problems for which 34 half-days were employed. In the first five problems the force involved was a detachment consisting of a regiment of infantry, a bat- tery of field artillery and sometimes a troop or more of cavalry. The problems were varied by placing them on different kinds of terrain, by varying the time available for the preparation of the position, and by variations in the probable direction, nature, and strength of the ex- pected attack. For problems involving a force of this size three half-days were employed. On the first half-day a general examination of the terrain was required, with a statement of the general position to be occupied ; division into sectors, and force assigned each; position and strength of the reserve; the position of the artillery, kind of fire to be employed and shelter to be constructed ; disposition and use of the cavalry. On the second half -day a more detailed examination of the terrain was required, with division of the force into first line and supports ; location and design of the infantry works and garrison of each; position and shelter 106 for supports; communications and approaches to be con- structed; obstacles; clearing of the foreground; and demolitions to be executed. On the third half-day the problem was discussed on the ground. During the discussion the instructor read a summary of the various solutions, and required different ofiBcers to explain any unusual dispositions, inviting a free discussion of all the points involved. Details were then made to trace the various trenches and positions. The locations were discussed by the whole class, and the best location at each point decided upon. When the time permitted, the whole line was traced on the ground simultaneously, by assigning officers as commanders of the various units and requiring them to issue their orders and trace the trenches of their commands. Each officer was provided with a sharpened stake about three feet long to which was attached 25 yards of tracing tape or cord. With these stakes the actual length of the trenches to be constructed could be traced on the ground by assign- ing the proper number of officers at each trench. In this way the officers can get a proper idea of the amount of ground covered by the trench of any unit. After a discussion of the problem an approved solu- tion was issued by the department. The sixth problem involved a force of a detached brigade consisting of three regiments of infantry, a squadron of cavalry, a battalion of field artillery, a com- pany of engineers, a company of signal corps, and a field hospital. For this problem five half-days were em- ployed. On the first half-day the following requirements were solved: General position to be taken up; the division into sectors, and the force asigned each ; the position and 107 stren"-th of the reserve ; the location of the field artillery, character of the protection to be provided, and kind of fire to be used ; disposition and use of the cavalry ; duties to be assigned the engineer and signal companies; loca- tion of the field hospital, ambulance and dressing stations. On the second half-day the first sector was taken up in detail in the same manner as in the smaller problems. The third half-day was devoted to a discussion of the previous work. On the fourth half -day the dispositions of the second sector were required ; and were discussed on the fifth half -day. The seventh problem involved the dispositions and defensive works of a division with siege artillery, which was part of a force of a corps of three divisions required to take up and hold, for about a month, a strong position covering the bridges across the Missouri at Leavenworth and Fort Leavenworth, assuming about ten days were available for the preparation of the position. Ten half-days were allowed for the solution and dis- cussion of this problem, which was taken up first in gen- eral and then in detail as in the sixth problem. The eighth problem involved an attack of a brigade, with siege and field artillery, an engineer battalion, signal company and field hospital, by regular siege methods, on a part of the line prepared for defense in the seventh problem; under the assumption that the position had been invested by a force of two corps with a siege train. Four half-days were devoted to this problem. On the first half-day were required: The location of the brigade park; the location of the siege artillery, character of the emplacements, observing stations; the 108 location of the field artillery, character of the protection to be provided. On the second half-day : Location and construction of the first parallel ; and the approaches to the front and rear. On the third half-day : Location and construction of the second and third parallels and approaches; duties assigned the engineer battalion and signal company ; loca- tion of field hospital, ambulance and dressing stations. The fourth half-day was devoted to a discussion of the problem, and laying out the parallels and approaches. 120. The chief value of these problems is their solu- tion on the terrain itself, and the actual laying out of the works on the ground. The map is only used to enable the instructor to determine the dispositions of each officer and to have a record of the work done by each. 121. The following general instructions were issued the Staff Class for the course : ( 1 ) Each officer will be equipped with a pad 5x8 inches, pencil, pocket knife, field glass, scale of yards 3 inches to 1 mile, scale of slopes, "Applied Principles of Field Fortification," and Part V, Engineer Field Manual. (2) A map for each problem, scale 3 inches to 1 mile, will be issued. (3) On the half-days scheduled for the discussion of problems, each officer will be issued tracing tape and stakes for locating trenches on the ground. (4) In the field problems all decisions and locations will be made after a careful examination of the ground. The map is issued only for purposes of identification and 109 record, and all works will be clearly and accurately indi- cated on it to scale. (5) The solution of the problem will include any necessary explanation of the notations made on the map ; brief reasons for decisions made or work to be executed ; drawings of profiles and sections of work not in the man- uals issued; estimates of time and force required to execute each part of the work; order in which each part is to be undertaken ; methods to be used ; tools and ma- terial necessary; arrangement of working parties, and total time to be devoted to the preparation of the position. 122. After several problems of the same type have been worked out in detail as above described, so that the student officers understand the amount and kind of work that can be done in a given time, the class may be given a situation and required to trace the trenches, approaches, points of support, and positions of supports, reserves, artillery, etc., in the time that it would have to be done in actual service. Officers may be assigned to commands, and required to issue their orders, with and without maps of the terrain. When the entire position has been traced upon the ground, the class should go over it and discuss the various locations. 123. The following problems selected from those given the Staff Class are given as examples of the simpler ones in the course. A solution of each problem is also given with the dispositions indicated on the map. It must be understood that these are in no sense map prob- lems, but are solved on the actual terrain, and that they are indicated on the map only to give an idea of the dis- positions made on the ground. 110 The maps are all of a scale of three inches to one mile, too small a scale to indicate the dispositions accu- rately. 124. In order to obtain the most benefit from these problems, it is recommended that the student make his own solutions on the map, before reading the solutions given. The map of Fort Leavenworth and Vicinity, scale 4 inches to 1 mile, is best suited for this purpose, and can be obtained from the Secretary of the Army Service Schools. Ill FIELD PROBLEM NUMBER ONE. General Situation : A Red battalion which was sent from Platte City, Mo., (12 miles east of the Taylor S. H.) to capture sup- plies collected at Lowemont, Kan., (6 miles west of the Taylor S. H.) having encountered a superior Blue force at the latter place, has retired via the Millwood road. Special Situation — Blue : The Blue pursuing force: 1st Infantry; Battery E, 3d Field Artillery; and Troop C, 5th Cavalry, is under command of Colonel A, who has orders to drive the Red force east of the Missouri River, and seize the Fort Leavenworth bridge. The remainder of the Blue force (2d and 3d Infan- try) which was delayed at Lowemont, cannot reach the Taylor S. H. before 3 p. m., September 23, 1908. At 10 A. M.. when Colonel A at the head of the main body arrives at Taylor S. H., he receives a captured mes- sage stating that five battalions of infantry and one bat- tery of field artiller}^ are on their way to reinforce the Red battalion, and expect to reach 986 at noon. The cavalry reports that the Red battalion has de- ployed on the edge of the woods near Kern, leaving a small force near 854. Colonel A decides to take up a position and to pre- pare it for defense, in order to hold back the enemy until the arrival of the remainder of the Blue force. The Leavenworth bridge has been destroyed. Required : 112 First Part. 1. The general position to be taken up. 2. Division into sectors, and force assigned each. 3. The position and strength of the reserve. 4. The position of the artillery, kind of fire to be employed and shelter to be constructed. 5. The disposition and use of the cavalry. Second Part. 6. For each sector : (a) The division into first line and supports. (b) Location and design of infantry works and garrison of each. (c) Position and shelter for supports. (d) Communications and approaches to be con- structed. (e) Obstacles to be constructed. (f) Clearing of the foreground. (g) Demolitions to be executed. Third Part. Discussion of the problem on the ground. SOLUTION FIELD PROBLEM NO. 1. First Part. 1. Hill 883— hill 875— hill 862, overlooking Salt Creek. This position has a clear field of from 400 to 600 3'-ards west of Salt Creek, a strong- obstacle in its front, and its flanks are well protected. Salt Creek is about fifty feet wide, with two to four feet of water, a very soft bottom, and vertical banks ten to fifteen feet high. 113 The extreme front is 1,500 yards, but the main position, excluding hill 862 and the positions of the supports, is 900 yards long. The working parties will be under long range infantry fire (1,600 yards) of the enemy at the edge of the woods east of Kern, but can be protected by a force thrown out to the front near Sharp. An alternative position is that along the ridge 932 — 886, which has the advantage of being out of range of the enemy, but would give up the obstacle of Salt Creek and the ground to the west, and would make a kiter advance all the more difficult. It has practically no bet- ter field of fire and has no strong positions for the flanks; see pars. 7-18 and 78-85. 2. Right sector : Kickapoo — Leavenworth road in- clusive to Millwood road exclusive. Left sector: Mill- wood road to hill 862, both inclusive. One battalion is assigned to each sector; the machine gun platoon to the left sector ; see pars. 22, 23 and 38. 3. At 865. one battalion. This is a central location, well covered by the road cut, and is near tlie more exposed right flank; see pars. 26 and 84. 4. At hill 886. Lidirect fire will be used at first ; i f necessary, direct fire will be used to reach the attacking infantry. No artificial cover will be constructed. This position is well protected from the hostile artillery which would probably be posted on Hancock Hill. It covers the edge of the woods east of Kern at a range of 3,200 yards, enfilades the ravines on each flank of the main infantry line and is well separated from the infantry positions ; see pars. 15, 30-34, 65, 67 and 68. 5. The cavalry will be ordered to keep t(iuch with the eneni}-; and when driven in, cover the right flank, sending a squad to the left. lU Second Part. 6. (a) For each sector: Three companies in the first line; no local supports; sector support, one company. Local or company supports will not be employed, as the reverse slopes are too gentle to afford cover from artil- lery fire ; the firing trenches will probably not be subjected to much artillery fire ; there are no good covered ap- proaches to the firing line, and the enemy's attack is likely to develop suddenly from Salt Creek; see pars. 23, 78, 79 and 82. (b) See map. Trenches are constructed for eight companies, 120 yards per company; total lengtli, 960 yards. With tasks of five feet per man, this will require 3/5X960=576 men. Profile : Standing trench, see figure 3. This has an area of cross section of 6 square feet. The soil is clay and may be classed as medium. 6^4= 1|^ hours required to complete the trench; see pars. 99 and 105. No con- cealment, loopholes, nor dummy trenches, as work will have to be done in view of the enemy, and the time is limited. Trench for H company will be concealed by the standing corn. The profile adopted with its low and flat parapet is very inconspicuous; see pars. 45 and 63. Machine gun emplacement constructed by platoon in two hours, with sand bag loopholes, covering the Mill- wood road; see pars. 73 and 116, and figure 22. Sand bags will be stored in trench so that the guns may be raised to fire over crest of parapet, if wider field of fire becomes necessary. . Tools required : Those carried by the men and in the wagons, including those of the reserve. See appen- 115 dix. Practically no tools can be obtained from the neighboring farms. Work will be done in one relief, seventy-two men in each company with sho\'els, twenty with picks. (c) See map. G Company will scar]:) the reverse slope and throw the earth to the front so as to give cover for men sitting, for a length of fifty yards. Tliis re- Cjuires 3/5X50=30 men, 4 hour, and will be done when the company completes its firing trench. A company is protected by a retired firing trench as shown on map; see par. 56. (d) None, on account of lack of time, men, and tools; see pars. 55 and 75. (e) None except those involved in f ; see par. 59. (f) Standing corn in front of E and H Companies broken down parallel to the front by dragging a log over it with a team. Trees and brush along the west side of Salt Creek slashed ; see par. 60. For this work there are detailed 105—92=13 men from each of the eight companies, for l-i- hours, with the axes and hatchets carried by the companies ; see appendix. (g) The Daniels houses in front of E and G Com- panies will be burned. The bridge at 789 should not be destroyed, as it would be needed for a future advance of the detachment; see par. 61. The work to be carried on simultaneously except the support position for G Company. The men will be worked 1^ hours in one relief. Total time to complete the preparation of the position, two hours. The 3d Battalion detailed for the reserve is assumed 116 to have been in the advance guard. It will keep down the fire of the enemy while the trenches are being- con- structed, by crossing Salt Creek and occupying the hill west of 854. When the work is completed it will fall back to its position at 865. Field Problem N^l Se»U 3Inchc5-lMil. 117 FIELD PROBLEM NUMBER TWO. General Situation : A Blue division is retreating through Leavenworth towards Atchison (18 miles northwest) pursued by a Red division. Special Situation — Blue : The Blue rear guard consisting of: 2d Infantry; Battery B, 3d Field Artillery ; Troops C and D, 7th Cav- alry, has, on September 14th halted for the night near the Taylor house on the Leavenworth-Kickapoo road. At 6 P. M. the rear guard commander receives orders to hold the ground south of Plum Creek until noon September 15th. Information is received that the immediate pur- suing force of th-e enemy consists of about 4,000 me'i of all arms, and is camped in Leavenworth, with out- posts on the ridge west of town. The rear guard commander decides to take up a defensive position and to fortify it as strongly as the time permits. Required : First Fart. 1. The general position to be taken up. 2. Division into sectors, and force assigned each. 3. The position and strength of the resen^e. 4. The position of the artillery, kind of fire to be employed, and shelter to be constructed. 5. The disposition and use of the cavalry. 118 Second Part. 6. For each sector : (a) The division into first hue and supports. (b) Location and design of infantry works awd garrison of each. (c) Position and sheker of supports. (d) Communications and approaches to be con- structed. (e) Obstacles to be constructed. (f) Clearing of the foreground. (g) Demolitions to be executed. Third Part. Discussion of the problem on the ground. SOLUTION FIELD PROBLEM NO. 2. First Part. 1. The main line of defense: Along the J- Aaron ridge from road 874 — 812 to include hill 862. An ad- vanced line from the Sprong house— liill 883 — hill 875 w^ill also be held. The main line lias a length of 1,800 yards; it has a good field of fire of about 800 yards; its left flank is strong, the right is rather weak, but can l)e covered by the artillery and cavalry ; the reverse slope is steep and offers good cover for the reserve; the hedges and barbed wire fences in froiit afford good olDstacles. In order to give more depth to the position and delay the enemy, the advanced line is occupied by part of the force; see par. 8. This position has a front of about 1.700 yards and a good field of fire of about 500 yards; its 110 flanks are weak, and tlie re\-erse slopes are too gentle to afford cover for supports and reserves from artillery fire; it is therefore not suitable for the main position. In this problem the ground south of Plum Creek has to be held for five or six hours, and this can best be done by causing the enemy to deploy before the advanced position, the defenders of which can retire by the ravines in rear without masking the fire from the main line ; see pars. 7-18 and 78-85. ' 2. Right sector: from the road S7A — 812 to the Leavenworth-Kickapoo road inclusive. Left sector : from the Leavenworth-Kickapoo road exclusive to hill 862 inclusive. One battalion is assigned to each sector, the machine gun platoon to the left ; see pars. 22, 23 and 38. 3. At 80'3, one battalion. This is a central position well covered by the steep slope; see pars. 26 and 84. 4. At hill 849. Indirect fire will be used. No arti- ficial cover will be constructed. This position covers the exposed right flank of each line and enfilades the ravines and railroad along which the main attack of the enemy is likely to be made. It is well separated from the in- fantry positions, especially the position of the reserve. It would be very difficult for the enemy's artillerv, which is probably superior, to find this position; and it is about 4,000 yards from Sentinel Hill and Bell Point near which the enemy's artillery would probably be located ; see ])ars. 15, 30-34, 65, 67 and 68. Crook Point affords a good observing station. 5. To reconnoiter to the front at daylight on Sep- tember 15th, gain contact with the enemv, delav his 120 advance, and cover the right tlank. sending a platoon to the left. To execute the demohtions given in 6 g. S^ecoiid Fart. 6. (a) For each sector: Two companies in trenches in the main hne, and two in the advanced hne ; see pars. 23, 78, 79 and 82. (b) See map. Trenches for 12 companies, 120 yards per company, total length, 1,440 yards. This re- quires 3/5X1440=864 men, or 72 men per company. Profile, standing trench, see figure 3. Area of cross section 6 square feet; 6^4= H hours, add 4 hour for night work; gives total time 2 hours. Trenches will be concealed with grass in places where it is growing, by corn in the corn fields, and by top soil in plowed ground. No loopholes will be constructed on account of lack of time and materials. Dummy parapets shown on the map will be constructed by plowing two or more furrows; see pars. 45, 63 and 64. Machine gun emplacement constructed by platoon in two hours with sand bag loopholes; see pars. 73 and 116, and figure 22. A wide field of fire will probable be neces- sary; this can be secured as explained in Problem No. 1. Tools required : Those carried by the men and in the wagons (see appendix) ; as there are not sufficient for all the men working at once, the work will be clone in two 2-hour reliefs. 492 men in each, including the work under d. Six teams and plows will be requisitioned from the , neighboring farms to assist in the construction of the trenches, and to make the dummy parapets. The reserve will assist in the construction of the trenches in the main line. FltLP PboblemN»2 I 121 (c) No supports proper will be used; the four com- panies in the main line will act as such for the four com- panies in the advanced line; see par. 56. (d) See map. For profile see pars. 55 and 113 and figure 17, 2 feet wide. Total length, 200 yards. Re- quires 3/5X200=120 men, 2 hours, or 30 men from each of the four companies on the advanced line. These approaches will enable the defenders of the advanced line to retire gradually under cover when the enemy's attack has sufficiently developed. (e) None except those involved in f ; see par. 59. (f) Standing corn in front of trenches broken down parallel to the front by dragging logs over it with teams ; see par. 60. (g) The steel bridges over Salt Creek at French- man's, at 789 on the Millwood road, and the railroad bridg-e at the mouth of Salt Creek will be disabled by explosives by the cavalry. Requires five pounds of dynamite per bridge, placed at the panel point of each truss, resting on the abutment; see par. 128. E. F. M. The railroad trestle at Miocene will be burned. Work will be done by patrols, four men to each bridge, after the cavalry has been forced behind Salt Creek. For tools and explosives carried by the cavalry, see appendix. .Total time to prepare position, four hours. No man will work more than two hours. The work should be commenced by 7 p. m. and finished by 11 p. m. by moon- light. All work except that in 6 g carried on simultan- eously. 122 FIELD PROBLEM NUMBER THREE. General Situation : A Blue army based on Kansas City is operating along the Misouri Pacific R. R. against a Red army, based on Omaha. Li order to protect its line of communications against cavalry raids of the enemy, the Blue army has fortified various points along the railroad in its rear. Special Situation — Blue : Colonel A, with the 6th Lifantry and Battery C, 3d Field Artillery, has been ordered to fortify Kickapoo, where there is a round-house, repair shops and materials for the repair of the railroad. It is not believed that an attack by more than a cavalry brigade with artillery is to be feared. No forces of the enemy are reported within sixty miles of Kickapoo. Required : First Part. 1. The general position to be fortified. 2. Division into sectors and force assigned each. 3. The position and strength of the reserve. 4. The position of the artillery, kind of fire to be employed and character of protection to be constructed. 5. Interior lines of defense. Second Port. 6. For each sector : (a) Division into first line and supports. (b) Location and design of infantry works in the first and interior lines. 123 (c) Position and shelter for supports. (d) Communications and approaches to be con- structed. (e) Obstacles to be constructed. (f) Clearing of the foreground. (g) Demolitions to be executed. Third Part. Discussion of the problem on the ground. SOLUTION FIELD PROBLEM NO. 3. First Part. 1. Hill 1,000— 873— B. Meyers— hill 903. This line is 3,000 yards long — too long for the garrison of the town; see pars. 78-85; but it is necessar}^ to hold it, as the field of fire on the left would be too restricted if the line was drawn in to the line 865 — hill 923. The field of fire on the right is good for 400-500 yards; on the left for 900-1,000 yards. Section Lane and Plum Creek form good obstacles on the left. The low ground along the Missouri River is intersected by numerous sloughs and is too marshy and wooded for an attack from the east ; see pars. 87-90. 2. Right sector : North and west of the line 842 — 865 — 38. Left sector : South and east of the same line. One battalion is assigned to each ; see pars. 22 and 23. 3. At 38 ; one battalion and machine gun platoon ; see pars. 26 and 38. 4. In the ravine northwest of hill 923. Indirect fire will be employed with cover of the type shown in figure 20. Other positions will be selected for indirect fire so 124 that all the slopes in front of the position may be swept by fire. Observing stations will be located on hills 1000, 903 and 923. The probable positions of the enemy's ar- tillery are Crook Point and hill 1042; see pars. 15, 27, 32, 35, 65, 67, and 68. 5. No interior line for right sector; for left, line 865 — hill 923. The front line is so long that it may be necessary, if an energetic attack is made, to draw in the left, giving a line about 1,500 yards long; see pars. 8. 9, and 19. Second Part. 6. (a) For each sector Three companies in the first line, each with one section in firing trenches and three in local support; sector support, one company; see pars. 23, 78, 79 and 82. (b) Location shown on map. Trenches for ten companies in the first line (9 company trenches and two platoon trenches) ; and for four companies in the second; 120 yards per company; total length 1,680 yards. Pro- file: Figure 4, see pars, 45 and 105. The soil is clay and may be classed as medium. To construct trenches will require 3/5X1,680=1,008 men, 2| hours. Loop- holes will be constructed of sod, sand bags, or stove pipe, materials to be obtained in vicinity. Trenches will be carefully concealed with sod, top soil or brush; see pars. 46 and 63. Splinter-proof cover will be provided for one section in each company trench, of type shown in figure 14. This will require |X 1,680=420 men, 2 hours; see pars. 49 and 112. Machine gun emplacements of type shown in figure 125 22, with the addition of splinter-proof cover constructed by platoon in four days at hill 1,000, hill 923. hill 903, and covering- the road and railroad east of hill 1,000; see map. Splinter-proof cover of type shown in figure 12. (c) Company supports shown on map at S. The sector supports at C and G. Protected by scarping re- verse slope, ^ yard per man. This will require 20O men four hours to construct. Similar shelter will be con- structed for the reserve by 100 men in four hours; see par. 56. (d) Approaches shown on map, leading to the more advanced trenches, where no natural covered approaches exist. Total length, 800 yards; profile, figure 17. These will require 480 men three hours to construct. The exist- ing lateral communications are sufficient; see pars. 55, 75 and 113. (e) Slashing in the wooded ravines leading to the position, along the river road, and where orchards and woods are cleared. Section Lane hedges prepared as an obstacle by clearing out to improve the field of fire and filling the road cuts with the debris. See f for estimate of time. High wire entanglements, five yards wide, constructed in front of trenches where no hedges or slashings have been prepared. Total length, 2,000 yards ; this will require 600 men four hours to construct, material taken from barbed wire fences ;see pars. 59 and 117. (f) Woods and orchards slashed in front of trenches to at least 600 yards. The houses that interfere with the field of fire will be torn down and the material used for splinter-proofs, etc. This will require the labor of 400 men four hours ; see pars. 60 and 117. 126 (g) None. The tools carried by the men and in the wagons are sufficient, with a few that can be obtained in the town and neighboring farms, inchiding teams and plows. Men will be worked four hours per day. The work should be undertaken in the following order: First line trenches, clearing, approaches, shelter for supports and reserve, second line trenches, obstacles, splinter-proofs. Total time recjuired to execute the work outlined above, three days of four hours. When this work has been completed, small working parties will be employed each day to extend the clearing of the foreground, im- prove the concealment of the trenches, strengthen the obstacles, and increase the protection for the supports and reserve. 127 FULB PHOBLXM N^3 Seals: 3 Inches -IMib I 127 APPENDIX. The following extracts from General Orders of the War Department give the tools carried by the different arms, which could be used for intrenching : Intrenching tools carried by a company of infan- try, G. O. No. 23, 1906: yi, ft. folding rule 4 hand axes 15 pick mattocks 3 wire cutters 45 intrenching shovels The following engineer equipment is furnished each company of infantry to be carried in the extra regimental wagon, G. O. No 221, 1907: Augur, i-inch i Nails, assorted, pounds 10 Axes 6 Pliers, wire cutting 7 Crowbar, 12 pounds i Rule, 2-foot. i Hatchets 6 Saw, hand, crosscut, with sheath . i Matchetes with sheaths .... 20 Rope, 2>^-inch, feet. ...... .250 The following engineer equipment is furnished the cavalry, to be carried on pack animals, G. O. No. 221, 1907 : To each troop : Augur, I -inch i Pick mattocks, large 5 Axes, 6-pound 4 Pliers, wire cutting 6 Crowbar i Rules, 2-foot 2 Hatchets 4 Saw, crosscut with sheath ... i Nails, assorted, pounds 5 Shovels, large 15 PACK DEMOLITION OUTFIT. To each squadron : Box, match, tin .... , i Fuse, instantaneous, feet . . . 200 Caps, detonating 100 Hammers, drilling, 7 pound . 2 Chisels, cold, j^-pound i Hammer, engineer's, 3 pound Crowbars 2 Pliers, nose cutting Drills, double bitted 2 Shoes, mule, sets Explosive, pounds 50 Spoon, drilling Fuse, Bickford, feet 200 Wrench, monkey 128 Allowance of tools for field service, G. O. No. 95, 1908: Hegimetital Headquarters. Infantry Axes 10 Hatchets. ...... 10 Pickaxes 3 Spades 3 A rtillery Axes 6 Hatchets 6 Pickaxes i Spades i Cavalry Axes 6 Hatchets 6 Pickaxes i Spades i Battalion Hdqrs. Sq. Hdqrs. 2 Band. M. O. P. Company, 6 6 4 4 Battery 3 3 7 7 Troop 6 6 4 4 Total in Regiment. 96 96 58 58 32 32 48 48 92 92 56 56 In addition to the above, each escort wagon carries one axe, one pickaxe, and one spade. The allowance of escort wagons, as follows : Regiment Infantry 23 Artilllery 23 Cavalry 34 Battalion 6 Company I lO Battery 3 Squadron 10 Troop 3 INDEX A Paragraph Abatis 59 Access to emplacements 70 Accommodation, magazine 51 Advanced method of conducting field problems 122 Advanced positions 8, 55 Advanced trenches , . 53-55 All-around attack 90 Ammunition, artillery, expense magazines for 69 Ammunition, artillery and rifle, storage 51 Angle of departure and fall of shrapnel 68 Approaches 12, 49, 55 Area of overhead cover 49 Armament 29 Arrangements for fire to the rear 48 Arthur, Port, location of batteries at 65 Arthur, Port, loophole cover used at 46, 110 Arthur, Port, Russian observing station at 71, 115 Arthur, Port, strength of garrison 85 Artillery ammunition, storage 51 Artillery, disposition of 27 Artillery, effect of 13, 44, 4a, 46, 56, 60, 61 Artillery, enemy unprovided with 92 Artillery expense magazines 69 Artillery fire, protection of supports from 56 Artillery fire, trenches to be screened from 63 Artillery fire, indirect 35, 68 Artillery, flash defilade 65 Artillery, form of emplacement for 66 Artillery, gun pit 67, 114 Artillery in redouts 42 Artillery, location of 15, 30-34, 65, 67, 68 Artillery, maximum effective ranges 65 Artillery, mobility of. 28 Artillery of each section 23 130 Paragraph Artillery positions 15, 30-38, 65-73 Artillery, position with reference to infantry 32 Artillery, strength of, in a defensive position 83 Artillery, tactical employment of, in defense 27-38 Attack, all-around 90 Attack, counter, influence on strength of garrison 78, 80 Attack, counter, placing of obstacles for 59 Attack, counter, second line to assist 9 Attack, fortifications on the 93-98 Attack, night 13. 74 Auxiliary means of defense , 74-77 B Background. 47, 63 Balloons, captive 6, 72 Batteries, location of at Port Arthur 65 Battery, siege 66 Battlefield, fortifications on the 94 Battlefield, organization of a defensive 10 Bombproots 49, 56 Buildings 60, 61 Bullet, penetration of rifle, machine gun and shrapnel 44 Calculation of men and time to execute defensive works 99-117 Camp, intrenched 6 Capacity of men for digging . 99 Captive ballons 6, 72 Character, general, of supporting points 41 Classes of defensive positions 5 Clearing of the foreground 60 Combination of works for command 23 Command 18 Command of parapet 45, 63 Command, low for artillery 65 Commander, section, telephone communication with 58 Communicating trench 55, 113 Communications 13, 14, 20, 40, 49, 53, 55, 75 Communications, interior 13, 75 Communications, telegraphic and telephonic 13, 58, 76 131 Paragraph Communications with the rear 55 Concealment 14, 40, 63 Concealment of artillery positions 65-67 Concealment of communicating trenches 55 Concealment of the interior of the defensive position 17 Conditions that a good profile should satisfy 45 Conditions that splinter-proofs should satisfy 49 Conditions to be sought in laying out trenches 14 Conditions to which every defensive position should conform. 10 Connection between fortification and tactics 2 Considerations determining strength of garrison 78 Contours, works to follow 41 Counter attacks, influence on strength of garrison 78, 80 Counter attacks, placing of obstacles for 59 Counter attacks, second line to assist 9 Course in field problems in fortication 119 Cover for supports 56 Cover, head 46 Cover, loophole 46, 108, 110 Cover, overhead 49, 52, 56, 66, 73, 109, 111, 112 Cover trenches 56 Crest, interior, height of 45, 63 Crest, interior, no breaks in 49 Crest, military 53 Crest, sky-line 63, 65 Cross fire 65 D Dead spaces 65 Defense, auxiliary means of 74-77 Defense, number of men per yard 78-85 Defense of small isolated posts occupied by detachments 86-92 Defense, tactical employment of artillery in 27-38 Defense, tactical organization of infantry in 22-26 Defensive field of battle, organization of 10 Defensive position, classes 5 Defensive position, concealment of interior 17 Defensive position, conditions to which every, should conform 10 Defensive position, examples of garrison of 85 Defensive position, garrison of 78-85 Defensive position in woods 62 132 Paragraph Defensive position, number of men per yard 78-85 Defensive position, strength of artillery 83 Defensive position, strength of engineers 83 Defensive position, strength of general reserve 84 Defensive position, strength of infantry ; 82 Defensive works, calculation of men and time to execute 99-117 Defensive works, drainage 57 Defilade, flash, for artillery 65 Defilade of roads 75 Demolition of houses and buildings 60 Departure, angle and slope of, for shrapnel 68 Design of works 1 , 39-64 Detachments, defense of small isolated posts occupied by. . . . 86-92 Determination of strength of garrison 78-85 Discussion of field problems in fortification 1 19, 122 Dispersion of guns 31 Dispersion of works 13 Disposition of artillery 27 Distance of defensive line from nucleus 6 Distance of obstacles from works 59 Distance of overhead cover from firing trench , 49 Ditchers, traction 101 Ditches 45 Division into sections 22 Double gangs 100 Drainage of defensive works 57 Dummy trenches or parapets 64 E Effect of weapons 13. 44, 46, 56, 60, 61 Elbow rest ... 45 Electric searchlights 74 Emplacements for artillery, design of 66, 67, 1 14 Emplacements for artillery, location of 30 Emplacements for machine guns 73, 116 Emplacements, means of access to 70 Employment of artillery, tactical 27-38 Enemy uncivilized or unprovided with artillery 92 Engineer Field Manual, referred to 42, 44, 46, 49, 59, 66, 92, 96, 98. 99, 102, 117, 121 Engineers, strength of, in a defensive position 83 133 Paragraph Engineers, technical parts of fortification assigned to 2 Entanglement, high wire 59 Expense magazine 69 Explosive shells, high, effect of 13, 44, 60, 61 Exterior slope of parapet 45, 63 F Fall, angle and slope of, for shrapnel 68 Field guns 15, 37, 67, 68 Field guns, maximum effective range 65 Field of battle, organization of defensive 10 Field of battle, intrenchments on the offensive 93-98 Field of fire 14. 54 Fire, cross 65 Fire, flank 40 Fire, frontal 40 Fire, grazing 53 Fire, high angle 15 Fire, indirect 15, 35, 68 Fire, oblique or enfilade 52 Fire to the rear, arrangements for 48 First line, strength of 23 Flanks of a defensive line 7 Flash defilade for artillery 65 Foreground, clearing 60 Foreground, covering 54 Form of emplacement for artillery 66, 67 Form of supporting points • 13 Forts 47. 89 Fortification, field problems in 118-124 Fortification, importance of 4 Fortification on the battlefield 94 Fortification on the offensive 93-98 Fortification, relation to tactics 2 Fortification, tactical aspect of 3 Fortified line of belt type 13 Fort Riley redout 42, 44, 102 134 G Paragraph Gangs, double 100 Garrison of points of support of second line 25 Garrison, strength of, for defensive work 78-85 General character of supporting points 41 General instructions for course in field problems 121 General objects to be aimed at in preparing an area for defense 40 General principles of fortification 1-21 General reserve 26, 84 Gorge 47 Gorge trench 48 Grazing fire 53 Gun pit 67, 114 Guns, dispersion of 31 Guns, field 15, 37, 65, 67, 68 Guns, indirect fire for 15, 35, 68 Guns, location of 33 Guns, machine '68, 73, 116 Guns, position for light 67 Guns, proportion of, to howitzers 29 Guns, ranges of field and siege .- 65 Guns, rapid fire 36 Guns, siege ... 29, 65, 66 H Hamiliton, General Ian, extracts from " Staff Officer's Scrap Book" 18, 46 Hasty intrenchments 79, 93, 97 Head cover 46, 108-111 Heavy artillery, location of emplacements for 30 High angle fire 15 High explosive shells, effect of 13, 44, 60, 61 High wire entanglement 59 Hill, location of works on 18, 53 Houses.. . . 60, 61 Howitzers, location of 34 Howitzers, proportion of, to guns 29 Howitzers, ranges of siege 65 135 I Paragraph Importance of fortification 4 Indirect fire 15, 35, 68 In-antry, position of artillery with reference to 32 Infantry, precedence of 16 Infantry, strength of in a defensive position 82 Infantry, tactical organization of, in defense 22-26 Infantry, works, design of 39-64 Instructions for course in field problems 121 Interior communications 75 Interior of defended position, concealment of 17 Interior slope c f parapet 45 Intervals between supporting points 11 Intrenched camp . 6 Intrenchments 43, 45, 105-113 Intrenchments, garrison of hasty 79 Intrenchments, hasty 79, 93-97 Intrenchments, tactical 97 Invisibility 14, 63, 65 Isolated posts occupied by detachments, defense of 86-92 J Japanese gun positions 15, 65 Japanese lines north of Mukden 50, 73 Japanese machine gun emplacement , 73 Japanese profiles 45, 107 Japanese redout 42, 104 Japanese use of intrenchments on offensive 97 Judson, Major W. V., extracts from report of 13, 63 K Kneeling trench 45, 97 Kuhn, Major J. E., extracts from report of 5, 15, 18, 42, 45, 46, 49, 63, 65, 97 Kuropatkin, General, comments on use of hasty intrenchments 97 136 L Paragraph Laying out trenches, conditions to be sought 14 Length of trenches 13, 52 Liaoyang 63, 97 Light guns 29, 67 Lighting of exterior slope 63 Line, defensive 7 Line, defensive, distance of from nucleus 6 Line, first, strength of 23 Line of approach 12 Line of retreat 21 Line of trench, location 18, 53 Line, second. 6, 19, 25 Line, sky 47, 53, 65 Location of artillery 15,. 30, 33, 34, 65 Location of depots of ammunition and supply 13 Location of fortifications on the offensive 96 Location of guns 33 Location of howitzers and mortars 34 Location of obstacles 59 Location of overhead cover 47 Location of roads 13 Location of supports 56 Location of reserves 13, 26 Location of trenches 18, 53, 54 Location of works in second line 19 Lookouts 50 Loophole cover 110 Loopholes 46, 108-111 Lying down trench 45 M Machine gun emplacement 73, 116 Machine gun bullets, penetration 44 Machine guns 38 Magazine accommodation 51 Magazines, expense 69 Man, capacity of average untrained for digging 99 Map, solution of field problems on 123, 124 Maximum effective ranges of field and siege guns 65 137 Paragraph Means of access to emplacements 70 Means of communication 20 Means of defense, auxiliary 74-77 Men per yard, number of 13, 45, 78-82. 85 Men required to execute defensive works 99-117 Military crest 53 Mobility of artillery 28 Mobility of reserve 26 Morrison, Major J. F., extracts from report of 4, 97 Mortars, location of 34 Mortars, range of siege 65 Nanshan Hill 63, 85 Night attacks and marches 13, 74 Notched parapet 46 Nucleus, distance from defensive line .... 6 Number of men per yard in defensive positions 13, 45, 78-82, 85 O Observing station 71, 115 Obstacles 54, 59, 92 Offensive, fortifications on the 93-98 Operations, siege 98 Organization of a defensive field of battle 10 Organization, tactical, of infantry in defense 22-26 Overhead cover 49, 52, 56, 66, 73, 109, 111, 112 Parados 47 Parapet, dummy 64 Parapet, exterior slope of 45, 63 Parapet, interior slope 45 Parapet, no projections above 49 Parapet, notched 46, 109 Parapet, relief of 45, 63 Parapet, thickness of 45 Penetration of rifle, machine gun and shrapnel bullets 44 Percussion shrapnel . . 44 138 Paragraph Pit, gun 67, 114 Pit, machine gun 73, 116 Pit, seepage 57 Plevna 85 Points, supporting, form of 13 Points, supporting, general character of 41 Points, supporting, intervals between 11 Points, supporting, of second line, garrison 25 Pom-poms 36, 74 Port Arthur, garrison of 85 Port Arthur, location of batteries at 65 Port Arthur, loophole cover used at 46, 110 Port Arthur, observing station at 71, 115 Port Arthur. Russian trench at 45 Position, artillery, dispersion of guns in. 31 Position of artillery with reference to infantry 32 Position of section reserve 24 Positions, advanced 8, 55 Positions, artillery 15, 30-38, 65-73 Positions, defensive, classes of 5 Positions, defensive, examples of garrison of 85 Positions, defensive, garrison of 78-85 Positions, defensive, in woods 62 Positions, defensive, strength of artillery 83 Positions, defensive, strength of general reserve 84 Positions, defensive, strength of infantry 82 Positions for light guns 67 Posts, defense of small isolated, by detachments 86-92 Precedence of infantry 16 Problems, field, in fortification 118-124 Profiles 43, 45, 63 Profiles, men and time required to execute 105-109 Proportion of guns to howitzers 29 Pumping for drainage 57 R Railroad 13, 75 Range, long, mid, short 54 Ranges of field and siege guns 65 Rapid-fire guns 36, 67 Rear, arrangements for fire to the 48 139 Paragraph Rear, communication with the 55 Redouts 13, 42, 44, 47, 48, 89, 102-104 Reichmann, Major Carl, extracts from report of 4, 45, 56 Relation of fortification to tactics 2 Relief of parapet 45 Reserve, general 26, 84 Reserve, section 24 Reserves on reverse slopes ... 68 Reserves, shelter for 90 Reserves, strength of 23, 84 Rest, elbow 45 Retired trenches 53 Retreat, lines of 21 Reverse slopes 56, 68 Ricochet 44 Ridge, location of trenches on ] 8, 53 Rifle, ammunition, storage 51 Rifle bullets, penetration 44 Riley, Fort, redout 42, 44, 102 Roads 12, 13, 75 Russian batteries at Port Arthur 65 Russian dummy parapets 64 Russian observing station 71, 115 Russian redout 42, 103 Russian trench at Port Arthur 45, 108 Sandbags for head cover 46 San Juan, Cuba 85 Screens 63 Searchlights, electric 74 Second line 6, 9, 19, 25 Section reserve, position of 24 Sections, artillery of 23 Sections, division into 22 Seepage pits 57 Sha River, use of hasty intrenchments at 97 Shells, high explosive, effect of 13, 44, 60, 61 Shelter for reserves 90 Shelter for supports 56 Shelters, overhead 49, 52, 56, 66, 109, 111, 112 140 Paragraph Shields, protection for guns with 67 Shrapnel, angle and slope of departure and fall 68 Shrapnel, effect of 13, 44, 45, 56 Siege battery 66 Siege guns, maximum effective range 65 Siege operations 98 Sight, nucleus to be kept out of, from enemy's position 6 Situation, tactical, of works 10 Sky-line 47,53,65 Slashings 59 Slope, exterior of parapet 45, 63 Slope, of departure and fall of shi'apnel 68 Slope, reverse 56, 68 Slope, trenches at foot of 53, 55 Small isolated posts occupied by detachments, defense of . . . 86, 92 Solution of field problems on map 123-124 Splinter proofs 49, 52, 56, 66, 109, 111, 112 Staff Class course in field problems in fortification 119 Standing trenches 45, 105-109 Station, observing 71, 115 Strength of artillery in a defensive position 83 Strength of engineers in a defensive position 83 Strength of first hne, supports and reserves 23 Strength of garrison of a defensive position 78-85 Strength of general reserve of a defensive position 84 Strength of infantry of a defensive position 82 Supporting points, form of 13 Supporting points, general character of 41 Supporting points, interval between 11 Supply, water 77, 90 Supports, cover for 56 Supports, on reverse slopes 68 Supports, position of 55 Supports, strength of 23 Supports, telephone communication with 58 T Table for indirect fire 68 Table giving time and men required to execute different work 117 Tactical aspect of fortifications 3 Tactical employment of artillery in defense 27-38 141 Paragraph Tactical organization of infantry in defense 22-26 Tactical situation of works 10 Tactics, relation of, to fortification 2 Target, works arranged to offer shallow 40 Tasks 99 Telegraphic communication 76 Telephonic communication 13, 24, 31 , 58, 76 Thickness of overhead cover . . . 49 Thickness of parapet 45 Timber on hillsides, location of trench in 53 Time required to execute defensive works 99-117 Traction ditchers 101 Traverses 45, 52, 66, 108 Trench, advanced 53, 54 Trench, arrangement of, for fire to the rear . 48 Trench, communicating 55, 113 Trench, distance of obstacles from 59 Trench, dummy 64 Trench, firing 45, 105-112 Trench, lying, kneeling, standing 45, 105-112 Trench, retired 53, 54 Trenches, cover 56 Trenches, drainage of 57 Trenches, length of 13, 52 Trenches, location of 18, 19, 53, 54 Trenches, telephone communication with 58 Triangular profile 45, 106 Type designs 1 U Uncivilized enemy 92 V Value of field problems in fortification 120 Villages 01 142 W Paragraph Walls 61 Water supply 77, 90- Weapons, effect of 44 Wells 77 Wire entanglement, high 59 Woods 53, 62 Wooded country, use of abatis and slashings in 59 Works, arrangement of 40 Works, calculation of time and men to construct 99-117 Works, combination of, for command 23 Works, design of 1. 39-64 Works, distance of obstacles from 59 Works, drainage of 57 Works, infantry, design of 39-64 Works, intervals between 11 Works, location of 18, 19, 53 Works, tactical situation of 10 UNIVERSITY OF CALIFORNIA LIBRARY Los Angeles This book is DUE on the last date stamped below. u -^< OCT 31^^ 61967 REC'D LD URL FEB 21 19 APR 9 8 198(1 Form L9-32m-8,'57(,C8680s4)444 3 1158 00273 1858 UC SOUTHERN REGIONAL LIBRARY FACILITY AA 001 166 912 4