CONFIDENTIAL FOR OFFICIAL USE ONLY NOTES ON THE USE OF MACHINE GUNS IN TRENCH WARFARE AND ON THE TRAINING OF MACHINE GUN UNITS COMPILED FROM FOREIGN REPORTS i V California .egional acility I ARMY WAR COLLEGE MARCH. 1917 WASHINGTON GOVERNMENT PRINTING OFFICE 1917 CONFIDENTIAL FOR OFFICIAL USE ONLY NOTES ON THE USE OF MACHINE GUNS IN TRENCH WARFARE AND ON THE TRAINING OF MACHINE GUN UNITS COMPILED FROM FOREIGN REPORTS ARMY WAR COLLEGE MARCH. 1917 WASHINGTON GOVERNMENT PRINTING OFFICE 1917 WAR DEPARTMENT. Document No. 580. Office of The Adjutant General. -tic. WAR DEPARTMENT, WASHINGTON, May 7, 1917. The following notes on the use of machine guns in trench warfare and on the training of machine-gun units are published for the information and guidance of all concerned. [2593173, A. G. O.] BY ORDER OP THE SECRETARY OP WAR! H. L. SCOTT, Major General, Chief of Staff. OFFICIAL: H. P. McCAIN, The Adjutant General. 3 MACHINE GUNS IN TRENCH WARFARE, In trench warfare as it exists in Europe, automatic machine rifles, popularly called machine guns, find their greatest use. Besides the trench, the essential elements of a trench line consist of a depth of wire and a front of machine guns. The tremendous stopping power of machine guns enable them to replace a large number of riflemen along this line, reducing to a minimum the men employed in actual defense, thereby leaving a large part of the force in reserve for use in the counter attack, or for the assumption of the offensive at another part of the line. Their use also reduces the daily wastage due to sickness, and prevents the offensive spirit of the Infantry from becoming impaired. Opposing belligerents in the present European struggle soon found it necessary to greatly increase the ratio of the number of machine guns per 1,000 Infantry rifles to 8, and in some areas to even larger figures. This ratio would give about 12 machine guns to one of our maximum strength Infantry regiments, and this number may be assumed as the minimum that would be required to properly defend the front that would be assigned to an Infantry regiment. Comparison table of automatic machine rifles in most general use in Europe. a a .a . 8 bib ** r . s . T3 - 3 bf s Name. li 1 11 Operating force. Cooling. l| 1 5 & X! W !& ] 1 d - 5 *4) 5 ** T 3 r r 5 0) c o fc B 48 250 Explosion and Water 450 to - fusee spring. 500 Vickers' light Colt 35 48 58 250 250 do Gas and spring ...do Air 500 400 70 360 30 30 do Air orfchange 250 to able). barrel. 400 4 nei 301 47 .do Air with alu- 400 minum radi- ator. 1 Jacket filled with water. I 2 Depending upon adjustment of tripod. s Folding. With magazine filled, 30 pounds. 6 MACHINE GUNS IN TRENCH WARFARE. TYPES OF AUTOMATIC MACHINE RIFLES. The term "machine gun" is popularly applied to all rifles of this character. Some foreign authorities, however, are careful to apply the name "machine gun " to automatic machine rifles of the Maxim, Vickers, and Colt types only, calling those of the Lewis, Light Hotchkiss. and Madsen types "Light automatic weapons," for the reason that the latter are a cross between the machine gun proper and the automatic rifle. The term ' ' automatic rifle ' ' implies a weapon which can replace the ordinary magazine rifle in the hands of the individual soldier. The powers and limitations of these two classes of automatic machine rifles have been carefully studied and each is used for the work to which it is best suited. The machine gun, or heavier type, is used where long-sustained fire of any kind is necessary^ as for: (a) Creating bands, or belts, of fire across the front of a defensive position. (6) Guarding the flanks of an attack by covering areas of ground with ftre. (c) Long range covering fire. (d) Indirect fire, etc. The lighter, or Lewis gun_tvpg. has generally been assigned to Infantry battalions and is considered ideal for supplementing^the lire power of riflemen, assisting them to gain lire .superiority and closely supporting thorn on all occasions in either attack or defense. The ^ewjs gun type is the first to go forward in an attacjfr and the last to be brought away in a retirement. This type enables fewer of the machine-gun type to be placed in the front line of an en- trenched position, reduces the number of Infantry in the front-line trenches, and enables positions won in an attack to be more quickly organized. THE UNITED STATES AUTOMATIC MACHINE RIFLE. The Benet-Mercie machine rifle, model of 1909, is an extremely light weapon. The gun alone weighs 30 pounds, or just a few pounds more than the Lewis gun, and it can be used in the f ront- line trenches or to accompany an Infantry line with the same facility that theLewis gun is used for these purposes in Europe at present . The Ordnance Department has recently modified a Vickers tripod for use with this gun, which will enable it to be used in the support trenches and other positions in rear, as are the Maxim, Vickers, and Colt machine guns abroad. The tripod weighs 45 pounds and can easily be carried by one man in a creeping or crawling position over all kinds of ground. MACHINE GUNS IN TRENCH WARFARE. 7 When mounted on this tripod, the Benet-Mercie machine rifle, model of 1909", can, upon occasion, deliver overhead fire, long range, indirect, and searching fire, traversing fire, etc. In other words, our automatic machine rifle can, upon occasion, play the r61es of the six types or two classes of machine rifles in use abroad. The gun has a case for protection against dirt and weather, which weighs about 16 pounds, so that the gun in its case weighing about 46 pounds, and the modified tripod weighing 45 pounds, can each be carried by a single man. As the War Department has recently adopted the Vickers as the heavy type machine gun for the United States Army, it is unlikely that the Benet-Mercie machine rifle will be called upon to do any work except that to which it is best suited. CHARACTERISTICS OF MACHINE GUNS. (a) Their power is limited to fire action. Machine guns by fire action alone can pave the way for an attack or ^rive back a hostile assaujK but they can not gain ground. The latter is almost 7 exclusively the role; of Infantry, which is capable of crossing all obstacles. Whenever, therefore, fire action alone is needed, ma- chine guns can be advantageously employed in preference to In- fantry, the latter being reserved for fire action combined with~ ^ movement. - , (6) Nature of fire. Machine gun fire ia cnnpentrajjefj,; therefore it will be most effective against a narrow and deep target. As Infantry normally advances in extended order, the best means of obtaining the above-mentioned target is by the use of oblique or enfilade fire. For this reason flanking fire should be the rule. Frontal fire should only be used against troops in close formations and against approaches, such as roads, bridges, defiles, communica- tion trenches, etc.; that is to say, against places where the enemy is compelled to take up dense formations on a narrow front. The traversing arrangement allows the gun to be turned through a con- siderable angle without moving the tripod, and with little exposure. (c) Invisibility. Owing to its small frontage it is easier to find a concealed position for a machine gun than for an equivalent number of riflemen. Hence, the possibilities of surprise effect are very great. Surprise is essential for the successful handling of machine guns. Flanking fire and surprise effect should always be sought for. (d) Mobility. The machine gun can go where a man can go on foot. 8 MACHINE GUNS IN TRENCH WARFARE. EMPLOYMENT. v The general principles governing the employment of machine guns are exactly the same in either open fighting or trench warfare, but to secure maximum results from the guns on all occasions the best method of applying these general principles to the peculiar condi- tions of the present war must be studied. The machine gun is a weapon of opportunity, but the machine- gun commander must not passively await the opportunity. He must keep in close touch with the situation and look for or make an opportunity for the successful employment of his guns. The ma- chine-gun officer must, therefore, be alert and handle his guns with boldness and cunning. The gunners must be determined, steady, and full of resource and initiative. ^COOPERATION. Cooperation is essential, not only between ,-^lhe machine guns of a single organization, but between those and the guns of adjacent units. Arrangements must be made for cross fire along the entire front, and for covering spaces not reached, or reached with difficulty, by artillery fire. OPENING FIRE. The general rule that machine guns must not open fire until a good target presents itself must not be carried to extremes, otherwise opportunities for the infliction of both moral and actual damage upon the enemy may be lost. The effect likely to be produced upon^the enemy is Ihe guiding^rjrinciple which justifies the opening of fire. It is often impossible to see anything "bFthe enemy, and likely positions for him to occupy must be looked for and these searched with fire, if necessary. Well-concealed machine guns may often direct their fire against: (1) Windows, doors, and roofs of houses thought to be occupied; (2) areas of standing crops and brush; (3) open spaces that small parties of the enemy are crossing; and (4) the enemy's firing line. NECESSITY may require machine guns to open fire upon un- suitable targets to assist the advance of the infantry, or to open fire in self-defense. SURPRISE EFFECT should always be the aim of the gun com- mander. Unless a surprise opening of fire is obtained, the gun de- tachment, and perhaps the gun itself, may be put out of action before any effect whatever has been obtained. POST OF DETACHMENT. As few men as possible should be around the gun. Those not actually necessary to work the gun should be engaged in the ammunition supply or under cover. INTERVAL BETWEEN GTJNS. If liable to be subjected to artillery fire, the interval between machine guns should be such MACHINE GUNS IN TRENCH WARFARE. 9 that no two guns will be included in the burst of a single shrapnel. This interval should never beJess than 20 yards. The gun positions should be such that the guns may give mutual support to one another by means of cross fire. Positions close to objects whose range is known to the enemy, or near prominent objects that will aid the enemy in finding their range, are to be avoided. A position in front of a dark background, or in ground covered with a suitable growth that will hinder observation, should be sought. During an advance or a retrograde movement the guns support each other by advanc- ing or retiring alternately, as the case may be. When infancy, the machine gjms should mix with the infantry and trv to disguise their identity as much as TINDER ARTILLERY FIRE. Great care must be taken to prevent the machine guns from being located by the artillery. If guns are shelled, they must change position at once. A move of 50 yards will generally be sufficient, f hese alternative or secondary j-ingjtjninH will always be select^ in advance. It may sometimes be desirable for the detachment to cease firing and to retire with the gun under cover until the shelling stops. If this is done, the hostile artillery may think the gun has been put out of action. When good targets present themselves, the machine guns may then open fire again from the same position. AGAINST ARTILLERY. The use of machine guns against artillery is exceptional. The following cases have been reported from abroad: (a) A section of machine guns worked forward to a concealed posi- tion 900 yards from a field battery in action, and bringing oblique fire against the battery, completely silenced it. (6) A field battery in action was taken in enfilade by a machine- gun section at 2,400 yards. The gunners fled and the battery was silenced. Frontal fire against shielded artillery will produce moral effect, which should be considerable; it should also greatly interfere with the supply of ammunition to the guns. CARE OF MACHINE GUNS. Every lull in the firing should be taken advantage of to clean and oil the gun. Springs should be tested and the gun inspected many times daily 'to be sure that it is always ready to respond in any emergency. The ammunition must be kept rhjaf^ When not in use the gun and ammunition should be covered with waterproof covers to protect them from water, dust. and dirt. 10 MACHINE GUNS IN TRENCH WARFARE. CONSIDERATIONS GOVERNING THE PLACING AND USE OF MACHINE GUNS IN TRENCH WARFARE .The answer to the question, "In what way must the machine guns at my disposal be placed and used to- best prevent the enemy from capturing these trenches?" will decide in almost every case how the machine guns must be located, distributed, and used. Unless the opposing trenches are so close together that a bombard- ment is impossible, an offensive with the object of breaking our line will always be preceded by an artillery preparation. The object of this bombardment will be to destroy the wire entanglements and other obstacles in front of our trenches, to destroy our trenches, dug-outs, artillery, machine guns, personnel, and strong points in the area to be attacked, and to prevent our reserves from being brought forward. After what the enemy considers a suitable artillery preparation, his grenadiers, infantry, and machine guns will move forward to cap- ture our trenches. If he has a superiority of artillery it must be expected that he will penetrate our line in places. But we must be prepared to receive him with several successive' belts of machine- gun fire that will delay him and inflict such losses upon him that he will be forced to use up his reserves before gaining any substantial advantages. By this time our counterattack should b~e able to drive him back with heavy losses. The duties of the machine guns of the defense may be enumerated to be: To replace as many riflemen as possible in the actual defense. To prevent the enemy from leaving his trenches. To sweep all ground between our trenches and those of the enemy. To prevent the enemy entering our trenches. To isolate portions of our trenches if captured. To sweep communication trenches leading from our front trenches to our support trenches. To sweep all ground between our support line and front line. To provide emergency belts of fire from the rear to replace broken belts. To engage enemy when concentrating for assault. To sweep covered approaches to enemy's defensive line. To engage enemy machine guns. To sweep ground in rear of the enemy's lines. To provide covering fire for counterattacks. These duties and the necessity for cooperation and coordination of effect require that all machine guns be under the direction of one officer. They also require guns to be distributed. MACHINE GUNS IN TRENCH WARFARE. 11 In or near the front line trenches. In or near the support trenches. In positions in rear along communicating trenches. In strong places in rear. In reserve. The number of guns available will govern the decision as to whether machine guns can be placed in all of these positions at one time. Reports from the present European war indicate that several successive lines of defence are not to be aimed at, but rather a defended area whose fortifications are laid out according to the nature of the ground, giving machine guns freedom of position that will not only reduce the chance of their being knocked out, but will also reduce to a minimum the number required to form any particular, belt or band of fire. Reports also indicate that machine-gun defence schemes must be divisional, in order to make these belts of fire continuous and to enable the construction of machine-gun fieldworks to go on with- out interruption. The scheme is worked out so as to hide the machine guns from enemy artillery and protect them from hostile bombers and snipers. LOCATION AND DISTRIBTJTION. In trench warfare, for the reasons given above, machine guns are distributed singly along the front of the position and in the area to be defended. Some of them are placed in the firing trenches, some in emplacements between these trenches and the wire entanglements, and some behind the parados just in rear of the front-line trenches. The positions of those in the firing trenches themselves are generally in salients, reentrants, or bends in the trench line. Those in front of, or in rear of the trench line, are generally placed in front of or in rear of a traverse. All of these locations are positions where they can best cross their fire for mutual support and where they can best bring an enfilading fire against an advancing infantry line. Emplacements in front of the firing line are made by digging narrow trenches of the same depth as the firing trench to the front, 15 or 20 feet, and then turning them to the right or left and widen- ing them out to accommodate the guns and crews. The gun rests solidly on the ground at the end of this cul de sac which is sunk just low enough below the natural ground to conceal it when in position. Some machine guns are placed along or near the line of the sup- port trenches, a short distance in rear. If the shape of the ground permits, these are so placed as to fire over the heads of troops in 12 MACHINE GUNS IN TRENCH WARFARE. the firing trenches, to aid in repelling an attack, also to bring fire on the first-line trenches in case they should be occupied by the enemy. Some of the machine guns are emplaced along the communicat- ing trenches and some around a strong point, 200 or 300 yards in rear of the front-line trenches, in such a way as to stop the enemy should he be able to capture the first line and support trenches, and to hold him until a counterattack can be delivered. TJie remainder of the machine guns are held in reserve, to replace casualties, or for use where the commander may decide and for instructional purposes. Plates 1, 2, 3, and 4 show the location of machine-gun emplacements and the methods of obtaining enfilade, covering, and cross-fire along three different fronts in Europe. Plates 5 and 6 show some details of the position shown in Plate 1. EMPLACEMENTS. In positions in the line where one. can be heavily bombarded, machine guns, or at any rate some of them, should be kept under cover day and night, but in those portions of the line where the enemy is so close that a bombardment is impossible and our only fear is a sudden rush, machine guns should be mounted in position ready loaded, always at night, and also during the daytime when the entanglements will not give sufficient time for them to get ready. The number of emplacements constructed must generally be greater than the number of machine guns assigned to the protected area, for guns which come under artillery fire must have an alterna- tive or secondary position and there must be emplacements for the machine guns in reserve and there must also be emplacements in reserve to take the place of those destroyed by the artillery bom- bardment. The enemy's bombardment of our front line must cease when his infantry arrives within about 200 yards of it, but it will increase in intensity against the trenches in rear, in order to prevent the infantry and machine guns in those trenches from participating in the defense. It follows, therefore, that our machine guns must be numerous enough along the front line and sufficiently strongly emplaced, so that enough of them will survive the bombardment and appear as soon as the artillery cone lifts and open fire on our wire entanglements and the ground in front of it. Owing to the extent of front attacked and to the difficulty of artillery observation, it is unlikely that an entire front-line system of trenches and machine-gun emplacements will be entirely pulver- ized by any artillery bombardment. The experience in Europe has been that some machine guns and crews have always survived, ready MACHINE GUNS IN TRENCH WARFARE. 13 to emerge and open a flanking, annihilating fire against the enemy's advancing infantry and the more oblique has been this cross fire the greater has been its effect. The emplacing of guns for cross fire, however, must not be be carried to the extreme. While the front of each gun is supposed to be protected by the cross fire of its neighbor, if the neighbor should meet with mishap or should be under artillery fire and unable to perform its function, fire to the front must be arranged for by the gun itself. Where opposing trenches are close together and machine guns would be subject to capture by raid if placed in the front-line trench or in front of it, this danger can be avoided by emplacing them behind the parados of the firing trench. This position will give a better field of fire, and, owing to the feeling of safety which this position inspires, the men will work their gun with more coolness and judgment than if the gun were sited in the parapet or in front of it. Plate 12 shows such a gun position connected by an underground passage to an ordinary infantry dugout, situated under the parapet. In this dugout underground cover is provided for the machine gun, its crew, as well as for the infantry squad pertaining to that trench. The dugout is also connected with the firing trench. Should the in- fantry squad be driven from the firing trench, or should this trench be destroyed, they will- take post behind the parados on the flanks of the machine gun. Plates 7, 8, 9, 10, and 11 show some types of open and protected machine-gun emplacements that have been used in the present war. If time and materials are available, some of the emplacements and dugouts near the front line must be made strong enough to resist the heaviest bombardment. It must be remembered that the stubborn defense of the front trenches will often depend on the machine guns, and that although the rifle garrison may sometimes be withdrawn to their bomb proofs and dugouts, the machine gunners must remain at their posts. There- fore, the machine guns and their personnel must have dugouts and emplacements that will survive the bombardment. The general experience of the effect of intensive bombardment on front-line trenches, when well carried out, has been that large por- tions of the parapet have ceased to exist ; and that unless machine-gun emplacements in the parapet are dug at ground level and covered by heavy beams, heavily supported, they will be destroyed at tho same time. A system of strong dugouts behind the parados in which 14 MACHINE GUNS IN TRENCH WARFARE. most of the machine guns can be kept safely during bombardment, will make them available when the bombardment is over. In connection with the emplacements there must be ample pro- tection for look-out men, who are detailed to give the signal for the mounting of the machine guns as soon as the artillery cones lift. It is reported that concrete emplacements and dugouts have been constructed at many important po'nts on the present trench line in Europe. Dugouts can be made by tunneling deep down under the parapet or parados, or by building shelter in a traverse. Plenty of earth, well supported by timber and inconspicuous from the front, is the aim in their construction. Machine-gun dugouts should be near the gun emplacements, and it seems to be the practice to build two dugouts for each gun. Into these are carried the gun, spare parts, and ammunition during a bombardment when the emplacements are too weak to remain in them. Emplacements should be constructed to look like the remainder of the trench and loopholes should be masked. The simplest form of emplacement is a semicircular pit about 2 feet deep with sand-bag revetment. Emplacements are numbered from right to left in any given section. Plate 12 shows a simple type of machine-gun loophole. Plate 13 is a type used for night firing. The simplest form is an arrangement whereby a steel shield and one or more sandbags can be removed from the revetment. The machine guns in the strong points should be emplaced to fire in all directions. The emplacement should be very strong, with dugouts, overhead cover, and ammunition depots, all protected by snipers and bombers, and the whole surrounded by wire. DIMENSIONS OF EMPLACEMENTS, DUGOUTS, AND LOOPHOLES. Dugouts and emplacements are made as small aa possible. The least dimension for a dugout for 4 men will be found to be about 6 by 5 by 4 feet. Minimum dimensions of emplacements are about the same, though a minimum of 5 by 4 by 4 feet is reported to be in use for both of these in the present European trenches. The firing platform must be from 18 to 24 inches below the height over which the gun is to fire. The loophole is generally 9 inches high by a dimension deter- mined by the thickness of the parapet and the number of degrees of traverse desired. MATERIALS. A loophole box is easily made of 2-inch plank. Sleepers of 6 by 4 inch material for roofing and upright posts of MACHINE GUNS IN TRENCH WARFARE. 15 7 by 4 inch dimensions will be found strong enough to use in emplace- ments and dugouts. Corrugated iron shegts may be used to cover the roof. Some nails will be needed, also sandbags and close mesh wire netting for revetting. Protection from rifle fire, shrapnel, and splinters from shells, bombs, and small high explosive shell from field guns, will generally be obtained by a parapet of earth 6J or 7 feet thick. Open emplace- ments should have this thickness of earth in front of them. Covered emplacements will be splinter proof if there is 20 inches of earth on top. AMMUNITION. An ammunition chamber must be prepared in each emplacement. In this is kept sufficient ammunition for immediate needs, a box of spare parts for the gun, oil, and cleaning materials. All alternative emplacements have these chambers fully equipped so that they may be occupied at a moment's notice if the regular emplacement has to be abandoned. Ammunition supply must be carefully thought out. Reserve ammunition in unopened boxes and arrangements for refilling empty strips or belts and making repairs are located, with" spare gunners, at a central dugout. Arrange- ments must be made to keep ammunition clean, and dry. It should be inspected daily. RANGE CARDS. Cards are prepared for each emplacement and alternative emplacement, giving reference point and ranges to all probable targets and to prominent objects. These are left in the emplacement day and night, whether occupied or not. Plate 14 shows a form used abroad. QENERAL REMARKS. To reduce losses during bombardments, when there is danger of a machine gun being struck, it is usual to dismount it, wrap in a water- proof covering, and remove it to a safe place, leaving the tripod in place so that the gun can be quickly mounted in case of emergency. If no safe place is available, the gun is put in the bottom of the trench, the waterproof covering preventing its becoming clogged if buried by shell fire. Gunners should not retire to the same dugout or to the same part of trench. After bombardment two men mount the gun, the remainder of the personnel remaining under cover, unless the signal of enemy attack is given, when, of course, no attention is paid to this precaution. As few men of the gun crew as possible, generally 3 or 4, remain in the front trenches, the others remain in dugouts and reserve trenches in rear; 16 MACHINE GUNS IN TRENCH WARFARE. One emplacement is iisually reserved for each gun as a "Battle emplacement," to be used only in case of enemy attack. Alter- native and dummy emplacements are used from day to day for firing at such targets as present themselves. A few rounds from these will deceive the enemy as to the location of best emplacements, as well as the number of guns along the line. Emplacements and dug- outs must be kept in good repair. Sandbags, chicken wire, and stakes are freely used in repairs. In each emplacement the limits that the machine gun can with safety be traversed without endangering friendly troops should be clearly marked by posts, stakes, or sandbags, arranged so as to make traversing beyond these limits impossible. OVERHEAD FIRE. Whenever machine guns are going to fire over our own trenches, the occupants of the trenches must be in- formed. LAYING OUT TRENCHES. When entrenchments are dug deliberately, they should be laid out with a view to defense by machine guns. The machine-gun positions should first be chosen and the trenches laid out accordingly, thus enabling the trenches to be held by machine guns, supported by a minimum number of riflemen. POST OF MACHINE-GUN COMMANDER. The commander must locate himself centrally so that messages may readily reach him, and so that he can coordinate the work of all the guns of his command according to the plan of the commander of the troops. He must have at hand orderlies and signal men well trained in maintaining communication with the different gun positions. EQUALIZING DUTIES. To give men and officers of machine- gun organizations sufficient rest, a regular roster should be kept. As only three or four men are needed with the gun in the front line at any one time, the remainder of the crew should be allowed to remain in reserve in the reserve trenches or reserve dugouts. This will enable men in the front line trenches to be relieved every 24 hours. Organizations should be relieved as often as possible. PERISCOPES. Periscopes should not be used from machine- gun position, but to one side of them. ILLUMINANTS. Each machine gun in the front line should have a Very pistol, or some other illuminant to show up enemy night attacks and enable fire to be directed on them. SNIPERS AND BOMBERS. When opposing trenches are close together, bombers and snipers should be detailed to protect the flanks of machine-gun positions. MACHINE GUNS IN TRENCH WARFARE. 17 Also during an attack, the machine guns will be worked to better advantage if a few men are assigned to their protection from bombing attacks of the enemy. ENEMY MACHINE GUNS. When contemplating an attack, if enemy machine guns are located, and they are not doing any ma- terial damage, it may be advisable to leave them alone, instead of firing at them and making them change their positions. Then, when our attack is launched, the guns may be in the same position and our guns may be able to keep them from firing on our troops. OBSERVATION. Officers, noncommissioned officers, and all men of maching-gun units must be well trained in the use of the telescope, both for observation, of fire and in picking up the enemy's machine guns. This requires constant practice. CONCEALMENT. Concealment must be aimed at in every case. Emplacements are made to look like the surrounding ground, so as not to attract the attention of enemy observing parties. Saps leading to emplacements are covered with canvas, brushwood, straw, sandbags, etc., to prevent photographic location by aircraft. The coverings can be easily removed if necessary. ORDERS. Owing to the fact that the immediate gun detach- ments change each 24 hours and organizations are relieved from trench duty frequently, it has been found necessary in the present trench warfare in Europe to have the orders for each gun detach- ment posted in the gun position so mistakes will not occur. These orders prescribe among other things: 1. That when detachments change, the piece shall be inspected that the points shown on the range card be pointed out carefully and that report be made whether the gun has been fired during the preceding relief; if so, at what target, and from which emplacement. 2. That fire is to be opened only by order of the gun commander, except in a sudden emergency. 3. That the gun, ammunition, and spare parts shall be cleaned and oiled daily. 4. Hours when gun will be mounted in emplacement. 5. Other rules necessary for the particular emplacement and the care of the gun. USE OF MACHINE GUNS IN THE DEFENSE IN TRENCH WARFARE. It has been previously stated that when machine guns are placed for the defense of an entrenched line, the guns of each section of the line must be arranged under the direction of one officer. This officer will be the machine-gun officer of a brigade, under the supervision of the division machine-gun 17 2 18 MACHINE GUNS IN TRENCH WARFARE. officer, for the reasons stated. Under hie direction, areas to be covered are allotted to each machine gun. These areas should slightly overlap. In allotting these areas, care must be taken that the whole of the area can actually be seen by the man firing the particular gun. The mere marking out of theoretical areas of fire on a map is not sufficient. It is the custom abroad to prepare a trench map showing the position of the machine guns and the areas covered by each. Machine-gun officers of adjacent brigades must confer together as to the placing of their flank guns, in order to insure that all ground in front of the intrenched line can be and will be swept. The machine-gun officer also studies the enemy's advanced trenches and finds out those portions that can not be reached by our artillery, or that can be reached only with difficulty, and arranges his machine guns so as to bring enfilade or oblique fire upon them. Fulfilling all of these conditions his aim will be to locate his guns so as to create several successive belts of machine-gun fire and to place his machine guns so as to bring enfilade or oblique fire against the enemy's trenches, the ground over which the enemy must pass should he attack, and against our own front line trenches should the enemy succeed in entering them. As previously stated, these objects will generally be achieved by placing the guns either in front of the trench, in a bend of the trench, in a salient, in a reentrant, or in or near support and communication trenches. The machine guns should always, if possible, be covered from fire from the front, while themselves being able to sweep the front of the intrenched line with cross fire. The front of each gun is swept by the fire of its neighboring machine gun, but in cases of emergency, all guns must have arrangements for firing to their own front. Some sandbags can be removed and the machine gun can be fired to the front through the loophole thus made, or the gun can be quickly removed from the tripod, if mounted, and fired over the parapet without it, or it may be fired from some other position pre- viously selected. DISTRIBUTION OF THE MACHINE GUNS. The shape of the ground will determine the distribution of the machine guns to a great extent. As a general rule some of the machine guns will be placed in or near the front line of trenches, for if it is intended to defend the front line obstinately, the machine guns may just make the difference between success and failure. Some will usually be placed in or near the support trenches to prevent the further advance of the enemy should he be able to enter the front line trenches. MACHINE GUNS IN TRENCH WARFARE. 19 If the ground is favorable some will be placed in concealed posi- tions in rear and arrangements made to fire over our trenches and sweep the ground in front of them, to fire through gaps in oiir line, to cover positions from which the enemy might prepare for an assault, to bring fire upon positions likely to be occupied by enemy machine guns, to assist our own troops to assault by protecting their flanks, and by overhead covering fire, and to use indirect fire against ground in rear of the enemy's lines. Some will, if possible, be placed in strong points farther to the rear, that must hold out till a counterstroke can be delivered. Any remaining guns are held in reserve to replace those disabled, to reinforce threatened points, and for instructional purposes. If there are not enough machine guns for all of these positions at one time, emplacements should at least be prepared in all of them and arrangements made so that machine guns may be quickly placed in any of these emplacements, when required. Arrangements are also made for rapid communication between all parts of the machine-gun defense area, and a quick ammunition supply system worked out. The brigade machine-gun officer must know the brigade com- mander's plans and he must work out ' the whole machine-gun defense scheme, so as to coordinate the use of his guns with these plans. His post must be near that of the brigade commander, or in such a position that he can easily communicate with him. USE OF MACHINE GUNS IN THE ATTACK. It has been found that continuous trench service impairs the offensive spirit of troops; so now when an attack is contemplated, fresh troops, who have not recently served in the trenches, are brought forward to make it. These are selected troops of best training and highest morale. Aeroplane maps of the front to be attacked are obtained and carefully studied. Besides distributing guns of different cali- bers along the front and collecting large quantities of ammunition for use during the artillery preparation, the infantry and machine guns are carefully instructed as to their tasks. The machine guns must be used in such a manner as to best aid the infantry. The brigade machine-gun officer must have full knowledge of the pkn of operations at the earliest possible moment, so that he can make detailed plans for the machine guns of the whole brigade. These plans will be made in consultation with the brigade commander, who will, after approval, issue the necessary orders for carrying out their part of the plan. 20 MACHINE GUNS IN TRENCH WARFARE. In making his detailed plan for the use of the machine guns of the brigade, the brigade machine-gun officer must make a careful study of the enemy's front line and its^relation to his own trenches. He must also study the ground in rear of the enemy's front line, which he will be able to do from the aeroplane maps. Machine guns are the weapons most likely to hold up an attack, and every effort must be made to locate enemy's machine guns, in order that some of our machine guns may be detailed in pairs, if possible, to engage them immediately the bombardment ceases. After studying the situation in connection with the brigade com- mander's plan, the brigade machine gun officer then divides up his guns and gives them the individual tasks that will coordinate the whole scheme. He must make sure that the machine gun positions that he will use at the beginning of the attack are in good condition, well supplied with ammunition, and that all arrangements have been made for rapid communication. In this manner each machine gun, or group of machine guns, will have a specific task allotted to it, and before the action commences, all concerned will thoroughly understand their duties and the par- ticular part that they are to play in the attack. All machine guns must be in their allotted places and ready for action by the time the artillery bombardment commences. THE ALLOTMENT. . 1. Some to go forward with the attacking Infantry. The number to go forward with the Infantry will be determined by the nature of the enemy's trenches, the length of the line to be attacked, and the number of machine guns available. These machine guns will go forward with the fourth wave of the attacking Infantry, mingling with the Infantry so as to make an inconspicuous target. These guns will, at first, use the light muzzle tripod. The heavy tripod will be brought forward after the Infantry is secure in the trenches that it is to capture. These machine guns hold themselves ready to go forward at the earliest moment and should not open fire until they reach the ad- vanced position. Their role will be to make good against a counterattack, the ground gained by the Infantry, and the approximate locality in which they will be mounted in the captured line should be settled before the advance begins. 2. Some to cover the Infantry advance. The positions that these machine guns will take will depend upon the configuration MACHINE GUNS IN TRENCH WARFARE. 21 of the ground and the position of the enemy trenches in relation to our own, as well as the nature of the attack. Their r61e is to deliver a covering and flanking fire. In playing this role some of the machine guns will be placed to prevent the cross fire by rifles and machine guns from the enemy trenches, situated on the flanks of the attack; some to bring oblique and enfilade fire on the part of the enemy trenches to be attacked ; and some to sweep the ground over which enemy reserves must move to the counterattack; some machine guns may be pushed out to the front through saps previously prepared to keep down the enemy's fire while our Infan- try is getting out of the trenches and through the wire entangle- ments. All covering machine gun crews should be instructed that when our Infantry masks the fire of their guns, they should, if possible, direct their fire past the flanks of the attacking Infantry, in order to keep down flanking fire and to prevent flank attacks; also, if our troops are forced to lie down between the trenches, that these ma- chine guns must try to keep down the fire of the enemy's rifles and machine guns. It must be understood L all commanders, that each machine gun has been given a specific task in a concerted plan and that the machine guns must not be interfered with or their orders changed by any one except the machine-gun commander or the commander of the brigade. 3. Some in reserve under the brigade commander. These machine guns will constitute a real reserve and will not be pushed into the fight too early. From positions in rear they can aid the attack by sweeping ground behind the enemy front line and by firing against counterattacks. Indirect fire may be used in these cases, if necessary. Cases have been reported where machine guns have been used to ajd the artillery preparation by firing upon and helping to destroy the wire entanglements. Such a use was effective, but the ex- penditure of ammunition was not commensurate with results pro- duced. AMMUNITION SUPPLY. An officer should be placed in charge of the ammunition supply, and all arrangements should be carefully made for depots and supply before the action begins. COMMUNICATION. The brigade machine-gun officer, as a rule, remains near the brigade commander. He will prepare for communication with all machine guns, or groups of guns, by the usual means, as well as by having ft sufficient number of orderlies on hand 22 MACHINE GUNS IN TRENCH WARFARE. for this purpose should the usual means of communication become disarranged. SUCCEEDING PHASES. If the attack is to consist of more than one phase, a separate plan must be made for each advance. METHOD OF GIVING ORDERS AND ALLOTTING TASKS. Reports indicate that "before an attack the brigade machine-gun officer assembles all officers and senior noncommissioned officers of the brigade machine gun units, and with the aeroplane maps of the enemy's trenches and the defended area to be attacked before him, he explains to them the plan of attack, allots the different tasks, and designates the position to be taken by each gun before the beginning of the attack and the point of the enemy's trench to which each will advance during the forward movement, announces the location of the ammunition depot, the name of the officer charged with ammunition supply, arrangements for communication, his position, and gives any other orders pertaining to the special case that may be necessary. LATE REPORTS. Reports received since this paper was written state that machine guns are now being manufactured in sufficient quantities to enable the Allies to make full use of them on the western front. One report states that a machine gun company with 8 guns, of the heavy type, has recently been added to each infantry battalion of a certain power, and that additional companies, belonging to "a machine gun corps," are being formed. These latter companies are handled in a manner similar to the artillery of the army, that is, they are assigned to special sectors according to contemplated operations and to the necessity for machine guns. These guns are all of the heavy type and are said to be in the proportion of 13 to every 1,000 infantry rifles. The report further states that every infantry company has 16 auto- matic rifles, weighing 18 pounds each. The power referred to seems to use this automatic rifle in the front line trenches as a substitute for the Lewis type gun. This automatic rifle is reported to use a magazine clip holding 20 cartridges, to fire at the rate of 150 rounds per minute, and to be quite accurate up to 600 yards, beyond which range the machine gun is used. EFFECT OF GAS ON MACHINE GUNS. The effect of gaa upon machine guns and cartridges and the method of employing the guns during a gas attack are given in the Synopsis of Principles at the end of this pamphlet. MACHINE GUNS IN TRENCH WARFARE. 23 TRAINING OF MACHINE-GUN UNITS. Most of the belligerents abroad now have "machine-gun training centers " to which officers and men selected for machine-gun service are sent for several weeks of intensive training before being for- warded to their organizations. ome of these centers have facilities ior training several thousand men, and they keep up a steady flow of trained men toward the front. Besides large target ranges, with which all centers are provided, there are at these centers facilities for training the personnel in grenade throwing, in signaling, and for" giving necessary instruc- tion in riding and in the care of animals. The sending of officers and men to these centers enables them to receive training from selected instructors, insures a uniform system throughout the service, and, as machine-gun officers invalided from the front are sent to these centers for light duty, the instruction is kept up to date. ' SELECTION OF PERSONNEL. In order to have a depend- able machine-gun force which can obtain the best results from the guns, a highly trained personnel is necessary. Officers and men must know their gun thoroughly. They must understand both the theoretical and practical sides of machine-gun employment, as well as the theory of machine-gun fire and of trajectories of bullets at the different ranges. The personnel should be carefully selected. The officers must be intelligent, resourceful, bold, and must have good judgment. The work is hard, so the men must have superior physique. They should be able to run or crawl from position to position carrying gun, tripod, or ammunition. Those unable to do this or without staying qualities should be transferred. They must have good eyesight. It has been the experience abroad that machine- gun units should be composed of men with a mechanical turn of mind. In addition to the above qualifications the men should, of course, be intelligent and have some education, otherwise they will not understand the range and elevation tables and the theoretical side of the machine-gun fire and of trajectories of bullets. Men selected for machine-gun service are chosen, as far as possible, from men who have had from six months' to one year's service in one of the other arms. Others selected are very promising men from training centers who have completed their preliminary training and are ready to take up their machine-gun work at once. Officers and men found unfit for machine-gun service are relieved or transferred at once. Abroad, every member of the detachment is trained in such a manner that he can serve on any duty or position 24 MACHINE GUNS IN TRENCH WARFARE. at the gun. ThJ8 training is necessary, as one shell may disable all the numbers operating the gun and the remainder of the detachment then engaged in ammunition supply or in reserve in the dugout must take over its service. After all are trained, the most efficient are appointed gunners and so serve until disabled. All officers and noncommissioned officers must be expert in the operation of the machine gun as well as in its theoretical and mechanical employment. PHYSICAL TRAINING. All members of the detachment should have daily physical exercises, running, etc. Nothing is better than running and crawling considerable distances with gun, tripod, and ammunition over all kinds of ground and mounting it in all kinds of positions. KNOWLEDGE OF GUN. While the officers and noncommis- sioned officers of machine-gun units must be experts in everything connected with the nomenclature of the machine gun, this knowl- edge is not necessary to the men of the gun detachment. It is not necessary that they should know the names of all of the parts of the gun, but it is necessary that each member of the gun detachment should have just as intimate knowledge of the machine gun and its parts as an infantry soldier has of his rifle. They should be required to take the gun apart and to assemble it again and again until this becomes second nature, and they should be quizzed and lectured about springs that may become weak and causes of stoppages and jama until the ability to locate these also become second nature. Not until such intimate knowledge is possessed by each member of the detachment can a gun detachment be considered ready for the advaced work of machine-gun employment. \ FIRE CONTROL. Perfect fire control will require careful training of all grades in: . 1. Estimating distances. 2. Pointing out and picking up targets. 3. Fire orders. 4. Transmission or passing of orders. 5. Visual training. Visual training is most necessary. It develops the soldier's powers of observation and eye for the ground, quickens his intelligence, and makes the designation and recognition of targets very easy. Training in transmission of orders impresses upon the soldier that it is his duty to make certain that all orders passed down are received and understood by those for whom they are intended. It is believed that the finger breadth and clock systems of target designation in vogue in our service can not be improved upon for MACHINE GUNS IN TRENCH WARFARE. 25 training in target designation when the men are sufficiently advanced to receive this instruction. TRAINING. Assuming that the personnel to be trained is so selected that it is ready to begin machine-gun work at once, the training of machine-gun units may be divided into the following parts: 1. Mechanical. 2. Formal drill (as prescribed by the Machine-Gun Drill Regula- tions) and training for fire control. 3. Advanced drill. 4. Range work. But not a shot should be fired on the range until the gunner knows everything about the gun and its use. 5. Construction and occupation of emplacements, dug-outs, com- munication trenches, etc. 6. Tactical training. 7. Training with other troops. While this training is practically that given for open warfare, the present war has proven that this training is sound and adapts itself easily to trench warfare whose general principles are exactly the same. It must be remembered that in no two military operations will the situation be exactly the same; therefore, machine-gun units must not be trained for any particular conditions of warfare. General principles and broad rules alone should guide their training. The fire value of a machine-gun well served is considered to equal that of at least 50 riflemen in open warfare, and it is claimed by some authorities that this value is even much greater in trench warfare. To obtain such a volume of fire delivered in the most effective manner would seem to justify an enormous amount of time, trouble, and expenditure of ammunition in machine-gun training. MECHANICAL TRAINING. The importance of this training must not be underestimated. Its thoroughness will depend upon the mechanical knowledge of the piece possessed by the officers and noncommissioned officers. While some of this training must neces- sarily be imparted by lecture and informal talks, in the main it is practical and must be acquired by the individual gunner himself. The machine gun and all accessories are given to each man in turn and he is required to take them apart and to reassemble them until he is thoroughly acquainted with the place and the use of each part. The names of parts are mentioned from time to time until the gunner learns the nomenclature of the piece. In the same way the individual members of the detachment are taught to mount and dismount the gun, to adjust the tripod, and to 26 MACHINE GUNS IN TRENCH WARFARE. dismantle it; to clean, oil, and care for the gun and all of the parts; to adjust, read, and set the sights; to load the ammunition strips and belts; load, fire, and unload the gun, with dummy cartridges; to feed the gun, to locate and remedy stoppages and jams, and to pack and unpack gun, tripod, ammunition, and all accessories upon the animals. Mechanical training must be reviewed and repeated from time to time so that the gunners will not become ' ' rusty " in their knowledge. FORMAL DRILL AND TRAINING FOR FIRE CONTROL. Formal drill, including the allocation of duties of all members of the unit, is prescribed by the Machine-Gun Drill Regulations. TRAINING FOR FIRE CONTROL. This training should begin early and should be given daily until all members of the unit are proficient, and thereafter the subject should be reviewed fre- quently in order that all members may be ready for actual service at any time. RANGING. The instructor, by lecture and diagrams on black- board, explains to the detachment the theory of the trajectories of bullets, explaining what is meant by the cone of dispersion, the danger zone, the beaten zone, the safety zone, the danger space, the 100 per cent zone,^the effective zone, the height of the trajectory, the line of sight, angle of elevation, etc. He also explains why it is necessary to find the correct distance or range from the gun to the target, defines ranging, i. e., "Any means adopted for ascertaining the sighting elevation required to hit a desired object." He explains the principal methods of ranging: By unit of measure. By mil system. ; In depth . - { By appearance of 1. By estimating distances..^ h Method of averages. Lateral. By mil system. 2. By instruments. (Special course of instruction must be given later.) 3. By observation of bullets. Explains other methods of ranging: 1. By use of maps. 2. Sound. 3. Information from other troops. 4. Forward and back reckoning. MACHINE GUNS IN TRENCH WARFARE. 27 Explains the preparation and use of range cards: For attack. For defense. Explains value and method of observation of fire: By signals. Methods of communication . . _ Telephone. Messenger. By quiz it is ascertained that the men understand what has been told them. The members of the unit are then given careful prac- tical courses of instruction in all branches of the subject in the open country. Ranging should form a part of each drill thereafter. VISUAL TRAINING. As stated previously, the object of this training is to develop the soldier's power of observation and eye for the ground, to quicken his intelligence and make the pointing out (Designation) and picking up (Recognition) of targets easy. This training broadens the soldier's military vocabulary and enables him to describe intelligently what he sees, as well as to recognize quickly what is described to him. If landscape targets are available, the instruction may begin at the barracks, preceded by a lecture or an informal talk by the in- structor. He explains: That the accuracy of modern weapons makes invisibility a necessity. That invisibility is obtained by 1. Smokeless powder. 2. Neutral colored uniforms and equipments. 3. Suitable formations. 4. Movement carried out under cover of darkness. 5. Careful study and use of the shape of the ground. That a trained eyesight is necessary, due to invisibility of the enemy. That the men will have difficulty at first in observing and telling what they see, due to differences of light, to the different appearance of objects in town and in the country, to an undeveloped brain power, and to a lack of words (military vocabulary). He impresses upon them that the standard each must aim at is 1. Ability to distinguish the enemy from his surroundings. 2. Ability to report what he has seen . 3. Ability to recognize objects described to him . 4. Ability to train the gun on the desired object. 5. Ability to study the ground and use it intelligently. 28 MACHINE GUNS IN TRENCH WARFARE. After these preliminary talks the instruction is given in the country, where a varied terrain is selected. 1. Single silhouette targets and groups of these targets are placed in different positions, with various backgrounds, and at varying dis- tances up to 800 or 1,000 yards. The men are then required to locate these targets, describe their location, count the number of figures in a group, discuss characteristics of the targets, etc. 2. Individual men and groups of men then take the place of the targets. An officer is sent out with these men to select their posi- tions, direct their movements and to cause blank cartridges to be fired so as to train the unit in locating sounds. The units under instruction then locate, recognize, and describe these targets in the same way as was done with the silhouettes. They also state the direction of the shots fired, their number, and whether they were fired by riflemen or by machine guns. 3. Definite lines in the landscape, areas of ground, and roads are then taken up, examined and described, in detail. Areas of ground are then divided into sections, both laterally and in depth (i. e., foreground, mid area, and background), and these sections are examined and described in detail, as above. The above instruction gradually passes into the Designation and Recognition of targets. The instructor defines Designation, i. e.i/'The shortest and most easily understood description of an aiming point by a commander." Also Recognition, i. e.: "The gunner's understanding of the exact point at which his commander wishes him to aim." He explains that accurate ' ' Recognition ' ' is necessary to insure that the cone of fire will strike the target desired. In this instruction the enemy's front is always pointed out, and the target and other objects pointed out must be described as seen by the naked eye. This is the normal method. Aids will not be used except when necessary. Later, when the instruction has advanced sufficiently, the men are taught to use the glasses and the telescope; they are also taught the "Designation" and "Recognition" of targets by the aid of 1. Reference points. 2. Finger breadths. 3. Clock-face method. All of this instruction, besides increasing the military vocabulary of the men and teaching them self-reliance, gives them a trained eyesight, and soon they will be able to recognize quickly the points upon which to aim the gun. MACHINE GUNS IN TRENCH WARFARE. 29 As soon as sufficient progress has been made, the machine gun is taken into the open country, where the instructor indicates aiming points, and the gun is pointed at the target as the gunner under- stands it. The "Recognition" by the gunner is always checked. FIRE ORDERS. Whenever fire is simulated, correct fire orders should always be given for the class of fire desired, so as to accustom the men as soon as possible to receiving and executing these orders. Before giving "Fire orders," the instructor must give a definition of the term, and he must also define "Ranging fire," "Rapid fire," "Searching fire," "Traversing fire," "Fire with combined sights," "Overhead fire," "Indirect fire," etc. He will explain: That the commander will take a position from which he can best observe the fire of his guns and the movements of his own troops and those of the enemy. That "Fire orders" may be verbal, signaled, or written. That they will be by word of mouth when practicable. That they may be transmitted by orderlies, who must be sure to repeat the order correctly and to see that it is understood. That ' ' Fire orders ' ' may be given to a single gun, to single platoons, to several platoons, or to the whole unit. That necessity may require them to be given direct to the squad leader instead of through the platoon commander. That there may be occasions when orders for the entire unit will have to be sent to the right or left gun and then passed from gun to gun along the line, and that the commander would then, if possible, take a position on or near a flank. That where "Fire orders" are given by word of mouth or repeated in this manner they must be given calmly, with telegraphic brevity, sufficiently loud for everyone concerned to hear, and with pauses so that each part may be understood, acted upon, and repeated if necessary. That it has been found best to designate the range first, to indi- cate the target next, and then the number of rounds and class of fire. That fire is usually begun and stopped by signals. That alterations of the range are given by the words "Up" or "Down," adding the required amount, as is done by artillery com- manders in giving their fire orders. < So that after sights are once set it will not be necessary for the gunner to take his eyes away from the direction of the target. 30 MACHINE GUNS IN TRENCH WARFARE. ADVANCED DRILL. The scope of the instruction given in this class of training will depend upon the ingenuity and the inter- est of the officers conducting the training. This instruction should be given where there is a varied terrain, as it has in view the adaption of the terrain to different assumed situa- tions and includes the carrying of gun, tripod, and ammunition by crawling and creeping over all kinds of ground to selected gun posi- tions without being seen, the occupation of these positions, the preparing of range cards to all likely positions of the enemy and to prominent objects, simulating suitable classes of fire from these positions, the selection of secondary positions and preparing range cards for them, the occupation of these secondary positions without observation by the enemy and simulating fire from them, then with- drawing to a position in rear or on a flank still without being seen, practicing fire orders in all of these positions, and communication to the rear and to other gun detachments, as well as providing for an adequate ammunition supply in all of these situations. This instruction naturally merges into tactical training, as the line of demarkation is rather dim when instruction is begun on varied ground. RANGE WORK. This ie perhaps the most important part of machine-gun training. After the men have passed tests in their elementary instruction, their range training is begun. A varied terrain must be selected for the range training in order that the proper kind of instruction may be given in all classes of fire. The training consists of two courses: I. Instructional. II. Advanced (including tests for classification and combat exercises). INSTRUCTIONAL. In this course officers and men are taught proper firing positions, correct laying, steady holding, and given practice at short known distances in fixed, distributed or travers- ing, and searching fire. By requiring each individual to prepare the machine gun for action, to mount it and make the preliminary tests necessary to assure him that the gun is "tuned up, " to set the sights, load, and take correct firing position, to hold the gun steady while firing, to correct stoppages and jams, and then to unload, dismount, and care for the gun, all in turn and without assistance, will develop self- confidence, a most necessary quality for a gunner. No records are kept of this firing other than of ammunition ex- pended and of progress made. No time limit should be imposed. MACHINE GUNS IN TRENCH WARFARE. 31 Each gunner under instruction should have ample time to learn his lesson, and when necessary the particular firing exercise should be repeated. The instructor watches the firer not the target. If mistakes are made he causes the fire to cease and makes his criticism. Range discipline is carefully maintained and all safety precau- tions are taken. ADVANCED RANGE WORK. The aim of this instruction is to train the units in all classes of fire and to such a degree of per- fection that machine-gun commanders may be sure that the fire from their guns will be applied to the best tactical advantage when the necessities of the combat remove them from the fire direction of superior officers. The practice includes ranging fire, observation of fire and making corrections due to the observation, firing from successive positions, firing with combined sights, night firing, searching fire, distributed or traversing fire, fire with an auxiliary line of sight, overhead fire, fire sweeping reverse slopes, and indirect fire. The ranges being unknown, the units apply their previous in- struction in finding the correct range, or fire a few ranging shots, observing the fire and making corrections. They are taught to study climatic conditions and to apply corrections of elevation, as well as the use of wind tables. Here they have practice in both classes of traversing fire on screens or targets, and they are taught how to deliver searching fire without leaving gaps between the effective zones. The dangers of overhead fire are pointed out, and the units are taught how and when this class of fire may be used with safety. They are given practice in sweeping reverse slopes and in the use of indirect fire, as well as practice in making necessary prep- arations for and executing night firing. After this course is completed a classification test is given, in which a time limit is introduced and gunners are qualified and rated. After the tactical training is well advanced, combat exercises are then taken up in connection therewith, the targets and groups of targets being arranged to appear at unknown ranges and to fit in with the particular tactical situation assumed. NOTES ON DIFFERENT CLASSES OF FIRE. An a general rule, machine-gun fire will not produce results commen- surate with the amount of ammunition expended unless the target is included within the area beaten by 75 per cent of the bullets directed upon it. If an error greater than half tha length of this zone is made in esti- mating the range, the fire will be ineffective. The error in a range 32 MACHINE GUNS IN TRENCH WARFARE. obtained by a range finder will probably be 3 to 5 per cent and that by other methods may be 10 or 15 per cent. It may also be remarked that the probability of error in the range increases with distance. The only way to be-sure that you have the correct range is by observa- tion of fire, which is not always possible. If observation is possible, the observation of a fe\v ranging shots will give you the necessary correction, but ranging shots can not be fired when surprise is in- tended and is of importance. In these cases an effective zone is made certain by the use of "Combined sights," or by "Searching fire." These classes of fire are used against deep targets, such as bridges and roads. COMBINED SIGHTS. In this class of fire two or more machine guns work together to increase the depth of the effective zone, by using different elevations and the same aiming point. The effective zone is thus lengthened though the density of fire is reduced. The difference of elevation between guns will depend upon the number of guns available, after taking into consideration the probable error in obtaining the range, and the effective zone for each gun at the particular range to be used. The differences of elevation must be such that no gaps will be left between the 75 per cent zones of the different guns. It seems to be the practice to use combined sights differing by an elevation of 100 yards for ranges between 800 yards and 1,200 yards, both inclusive, and sights differing by 50 yards above 1,200 yards. The machine-gun commander must use his judgment in modifying the application of the above, in accordance with the facilities that he has for accurately obtaining the range, so that the desired tactical advantage will be gained without a useless expenditure of ammuni- tion. Firing with combined sights should be discontinued as soon as accurate observation of the strike of the bullets can be obtained. A simple way of giving the fire orders for combined sights is to give the minimum elevation to a flank gun (usually the left) and to an- nounce the difference of elevation desired. If, as a result of his observation, or for other reasons, the machine-gun commander wishes to alter the sighting, the quickest method will be to bring the ele- vation of the left-hand gun above that of the right-hand gun or to lower the elevation of the right-hand gun below that of the left- hand gun, according to whether the elevation is to be increased or decreased. / MACHINE GUNS IN TRENCH WARFARE. 33 SEARCHING FIRE. This class of fire is used when only one or two machine guns are available and combined sights will not or are not likely to overcome errors in obtaining the correct range. This class of fire requires quite a degree of skill on the part of the gunner to avoid gaps in the swept zone. The size of the shot groups or bursts to be fired will depend on the nature of the target engaged. A simple method of using this class of fire is given in one report a.s follows: When one gun is being employed for searching, the sights arc adjusted so that the first shot group will include the lowest range to be searched, which is determined by the expected error in the range. The gun is now laid on the aiming point and the sights adjusted, without relaying the gun, so that the last shot group will include the highest range to be searched. The line of sight will now strike the ground short of the aiming point. A burst is now fired (10, 20, or 30 shots, depending upon the nature of the target), after which the elevating wheel is turned to cause the next burst or group to strike sufficiently far beyond the first to insure an overlap of the effective zones. This is continued until the line of sight is again brought on to the aiming point. When using two guns, the left gun will act as described above, while the sights of the right gun will be adjusted in the first instance to the highest limit to be searched and will work down to the lowest limit. Searching fire will be discontinued when observation of results is obtained. The effect of ground rising with respect to the line of sight must be taken into consideration when either combined sights or search- ing fire is employed. DISTRIBUTED OR TRAVERSING FIRE. This class of fire is employed against a linear target. The normal method of traversing is by means of a series of small groups, with the object of covering as wide a front as possible and producing the desired effect without too great an expenditure of ammunition. In the normal method the bursts or groups consist of only 5 or 10 shots. This method has certain disadvantages. It is slow and requires careful training. The effect is a puncturing one at regular intervals instead of a mowing effect, which is to be desired. The other method of traversing is called the "Swinging traverse." In this method the traversing clamp is kept fairly loose, and the 17 3 34 irun is 8W#ng evenly fnm side ;to side. in <:a.-e of u rush, whjen .11 10 normal me! hod .\vmild bo Ux>. ,s}owv The e.xpemli- iinv of ajjruni>^qni / is #o.gra.t when the '-^winging tra\e. used that it may be said that : JJt4s)metbod. wjji Jbe reserved tos emer- gencies. tfire qa^.be dj^rihuU-d by this method over 30 >. front at close ranges in five seconds. NIGHT FWNG.-Jf cueuwafrnoi's W J1J allow.it. the gun in mounted and laid by day and left till night. At night some kin a -crceu sc- oured to the open fcide of a box. in which is placed an oniiiuuy jMge lantern or au eJei.-iric miv!. Tlit.' screen is marked with linjap to permit pf ^e^fphing ^nd traversing within dcfmilo limit.-, li the horizontal ilines of the 3?neeij fire [J.,w^ch,^part. ; eadi interval will aubtend a t a^^^ IRiWnuteq^h^n jt^BjCE^nis 10 yards from Uu- gun. The amount th^t W E^i^wt^s^pr^a^nts in^rangQ |can : bereftfUly ascertained t&ftJB the tafclp ,al>Q;ing the -angles of elevation inr lh' gun. The .vertrtC-aUinefl ai;e ^^ncj^s .Rpa^j Flfuph/ will give a tiou of 2 i^ti^^^Q.jjfarjdft^fr^ftgQi^^^t^screea is in yards from the gun. .tnioq sniraif: 91(7 gun; . pJeitioTR ,js[ ,ei^FK>f4< #P that the un can n< t l>< laid during the day or where fire may be necessary from several -dUflwr^t;pc^itions i ,aH i ap^eTOep^i.YfJllji,aMe4a be -made ta bring ih, gun and tripod up under cover of darkness and mount ijvso as t" open fire \sheiv ipquired. t , .-,. i Wlu'le itds still light itbe-igUfli-pfisiiJionriigBetepliQd, This of pQurse must be selected with reference to the target it w intended t<> <-n- gage> Astak^Jafli^pto<^jte!*^; lf< mor^rihan, one target id to be engngedvother etaktw are aligned ,l>?t^-e< < ,th i e ! tlCrgetd auih borf; 6 - VI "66871' MACHINE GUNS Iff TRENCH WARFARE. 86 If owing to the proximity of the enemy, it should be found im- possible to place a stake in front of the selected gun position, then a stake is first driven at the selected gun position and a stake in rear is. placed in^ accurate alignmentr-w ih 'it -an,(Ji the target to be engaged. A ft or dark a staice'tt)- yards out in front is lined np with the other two by means of a trench lanter&s Auxiliary aiming marks are placed at night at the exact positions of the 10-yard stakes. The tripod is brought forward and set up exactly over the stake at the gun position. The gun is then mounted, given the proper eleva- tion," and then the line of sight is brought to the intersection of the central horizontal and vertical lines of the night firing screen. Allowance for wiadage is now made by using the vertical lines of the screen. One report states that the flash- of the machine giAji in night firing will soon disclose its 'position, unless a burlap -iif tain^ia used to screen the flash. The angle of departure. .Ctak^R^Jfajp -the range tables) is the angle between the line of departure of sthje 1 ? bullet and the line from the gun to the target. The angle of position is the angle that the line from gun to target makes with. ..the horizontal line through the gun. The quadrant elevation is the angle between the line of departure of the bullet and the horizontal line tUjQUgh the gun. It is the sum of angle of departure and the angig^of jKj&frJGjtt -jphen the target is above the level of the gun and to fcke ])iekl up correctly. There are several methods of obtaining the safety angletfof 30 and 60 minutes, in use abroad: (a) By m'eans of prismatic field-glasses, graticulated for the par- ticular kind of ammunition in usel For example, the distance be- tween the zero line and the 600 or 700 or 800 yard graticule would subtend the desired angle for ranges-1,000 yards or under, white the distance between the zero line and trfe T,CfbO or 1,100 yard graticule would give the angle for distances between l,000~and 1,500 yards. This method of obtaining tire safety angles is 1 unreliable, since it is quite possible for the wrong lines to be used. (6) By means of a machine gunner's protractor. In this method the protractor is held vertically at the full length of the cord' from the eye. Lines have jfteVibusly been placed upon the protractor at such' a distance from cadi other as to marlc angles of 30 minutes and eOTiiinutes when held at a certain fixed distance from' the eye. (r) By means of the tangent sight: Lay the gun on the target with the correct elevation, then if the distance to the target is under 900 yards, move the slide up 400 yards; if 900 yards or mbre, move up the slide 256 yards. In each case adopt the auxiliary aiming mark thus found . Plate 15. (These amounts will differ with our ammunition.) MACHINE ouire r*r TRENCH; WARFARE. 39 The report (Hflc'tis^-s'tte advantages and disadvantages of this lat- t.-r method as folfow*. In one s-enso if is against the pvinviph'S of machine-gun training which 'emphasizes the impofctartte of 'the 1 gunner looking 'at the target and not alang his sights' when firhig. Again the pinner, having carefully maried'the-spot on which the sights are aligned, is trained to take the heads of the advancing infantry as his'aiming mark when they reach and move in advance of this spot, or rather when their heads come into Ma Ifcte of iftgiiti,' a TjIroteMiflg which may not always l>e desirable. The chief advantages are that eacH gtasvean o>rfairv t'he safety angle for the particular troops he is supporting 1 ;' when^t^ trWyps \\ h" are being supported' pass tfhe s^>^1ttafrke'd / .a!aA^iniing mark, the gniM^'eatt ! stin-contihAi6 > iil^^1)y'e ; l l eVating tlie gufi PO as to main- tain his aim on their 'hea*. ' 'AB tttisf ad\-atte^ c6tttfttitrts'/ Irfe aim is kept on their heads by turning the elevati^fwTleje!: By'this means, ccK'ermgftre is'itidititoined ittWiltHi Mendly troops reach- tlfe-ehemy 's position. The conefr'of ffi^'JCass over the heads of iriendlj'- troops with a margin of safety at each advance, and seaa^frgrotiild'iii rear of the defended position possibly occupied try supports'atod 1 reserves. The disadX"Eflitagea ! ol ! M*i4'fethod can 1)6 miflimfeetl' l>y the macMne-givfl l c(Wttmarotractor as a chwk ow tile ifirer, and this id 1 particularly ne'efeis6ary'wheft f the nattri-4io*'thf 'ground ontd wiiieh'firfe ib being 1 diredWd gives ar'folse impression a r'^arda . the limit of safety. INDIBfiCT FIBE. This class of fire wilt be need mr fare occasions. It is rendered possible by the "fixed mountfeflgf" of the machine gun. Lewi&gunfi and others of a similarii!atltfe"mu8f7iCTtv(\; imme- diately prior to firing. GRATICTTLE METHOD. Byl kheans of graticules cut across the focal planeiof a pair of prisoiatic field- gJassesi! iaidlrtct 1 fee can bd iaa qfuickly applied as /ordinary direcfe'fire. These graticules represent the angles of devotion for ithegttn- with sofae* .pathticHlar bind o/artmunfeHW. Thftitepmlost 'griaticnle 'rbjire- sertta i aetw;i an'd life tlbsee belo\r represeskt'eVery 100 yards upward from 2001 yards: ; Proceed as follow?: . , p ed; c . Jj. l 0btain;thBratJge'tath*ftargett:;! ,i- .'.{ b-r '2 . Movw to; u iprieitioii'Awlience iyioti can'obBerMe. fene- target tkrbugh gratitulatetttifield-glaseeai look at the target in('T!ioiri tajg^t i faMs- afciOBs the targets, then-Aodc I or/ suitable aiming mark- above; th&targB* !('h>k;hi-fflmTng marki Bidtetr Ue viaibleifrom the-posit>ton.wheiSa;thtegBnTJs"Hi)Dunted) and >*ee/ whidh( graitt6le;fail8 across* this- aiiriingi'inirb J (Ehe* frange^DorareBpond ing; to this gratictilei givefe tlic'angfe of de- parture at -wihDch t; to open-^ife; neing;the snitaible' aiiiung mark to lay the gun on.' B^thlsimeandigaieat'accaraDy'ie obtained -white' the gua and* ifirer are invisible to tbe^^neiny. ; b .Uhis >methbd ibecomei;iiiaccnraie' wben'the seVe of tb^offt^i indicate the 1 range tovthe taasget, arioliberi nwthod' :othef than the norinal'muftt be ( There are roughly as i many, clicks on th*: ritch( ot'it sight as there aire ]kiiadke IiONG BA1T&E SEARCHING FI3l!Bi--In ttenelb "warfaiv, where the positions of our own and the enemy's t&6ps!af!e^ie9*Jy marked, long>rdnge^6ilrtHi^r^d^r^thea>6^ may eomtetimtefl'be saiilyf employed. Tb' abtanr the best resnlfa^ observation vrf thre 1 strike of tlib bnliets ia eesetokifiit; The element of chance, daw to* errors ifi 1 raaging, cli- inatic conditions, etrora as to the exact poaitJlon of the guto; etc., will thus be removed. MACHINE GUNS IN TRENCH WARFARE. 4ft When observation of results is possible, fire may be directed on the hostile support or .reserve, lines, communication tren< -lie.--, ci<-. When no observation is posniblp, the moat that can b<; hoped fur is to engage an area) of grotiad with the object' of sweeping reverse^ slopes of hills which are defiladed from fire at> sthbrfc ranges, inter- rupting trallic on roads, etc. To insure the safety of our own troops;! the- following must at all t inios l>o strictly adheiVxl to: I. No target should be engaged at a r&nge of less -than 1,500-yards. L>. Tim guns must never 'be more> Ihafar I/, 500 yards -distant from bodies of out- own troops, over \vhom they asre'firing, 3. \\lien 1 the guna are 1,000 yasdB' or; under "fromf ourntrdops. the range at which' they' are fired must be such aaJta-ididureitlie'ceriter of the cone Wf fii*e psu&rig at- least 60 feet oven theai) beads. When the guns are between 1,000 yards andiJi,50^ yapdiEroin our o\vn troops, this height rmtst bo 12& f(3et. 4. The p>isit ton of OT*T own ''troops: with-, reference 'ticJ the gun nmst be accurate! y> ascertained. >. Whon there is ^negative aoagle of pasitiorrf between i the gttn. and target, or a positive angle of position between the.gU!n ! and ! ou!F own troops, the heights shown iii the trajectory tab-le -will be reduced. The guns musl. therefore, beiileved back t6 fire at a-raflge, amount. 9. A worn barrel should not be used. 10. All calculations must be carefully checked before firing*. I 1. Troops over whom fire ia iff be opened must be cautidned, and a certificate to this effect signed by the machine-gun cenimaider. 12. Clinometers-, if used, must be tested, and if necessary, cor- rected, before use. To direct fire on a targets invisible to the gtme, a map having a scale of not loss than 3 inchest to one mile must be us. M!. In order to find the correct elevation, the map must be con- _ toured, tenrooa ed y 44 MACHINE GUNS IN TRENCH WARFARE. The following information is required from the map: The exact position of the gun, the direction and distance between the gun and the target, and the angle of positkih of target with re- spect to the gun. Small errors in the position of the gun will cause serious errors in direction. The position of the gun on the map can be found by "resection. " (Par. 34, Engineer Field Manual.) The direction of the target can be obtained bv means of a compass bearing, or by the use of the traversing dial. To find the direction with the traversing dial proceed as follows: Select some convenient object visible from the gun position, which can be identified on the map for use as a reference object. On the map draw lines from the gun position to the reference object and target. Measure with a protractor the angle formed by these two lines at the gun position. Place the gun in position on the ground and lay on the reference object. Note the reading shown by the pointer on the dial. Add or deduct this reading from the angle already obtained from the map, according to whether the reference object is to the left or right of the target. When the reference object it is desired to use can not be identified on the map, its compass bearing must be taken from the gun posi- tion and "plotted" on the map. The required angle can then be measured and used with the traversing dial as before. To place the required elevation on the gun use either of the methods of "Indirect fire" previously described (spirit level or clinometer). To facilitate the making of notes on angles of elevation, bearings, safety of our own troops, etc., it is advisable to enlarge the area to be engaged. SiOPCS (<-- /tOO yds. I By selecting the most suitable range it is easy to adjust the fire of machine guns, so that reverse slopes of hills may be accurately swept by grazing fire. MACHINE GUNS IN TRENCH WARFARE. 4.5 The following example will show how the suitable range is selected : From a contoured map it is noted that the enemy occupies a crest line 180 feet above sea level, the 160-foot contour being 300 yards in rear of the crest line. Our troops are in position in a valley which is 120 feet above sea level. Deduct 120 feet from the other two heights; the heights above our position are seen to be 60 and 40 feet, respectively, and our bullets are required to descend from 60 feet to 40 feet in 300 yards; that is, from 60 feet to 54 feet in 100 yards. Now, inspect the trajectory table (Publication No. 1923, Descrip- tion and Rules for the Management of the United States Rifle, Caliber .30, Model of 1903). Any fall of 6 feet in 100 yards will not do, as it is necessary to arrange that the bullet shall first rise to 60 feet. On inspection it is found that the 1,600-yards trajectory satisfies the condition as to rise of 60 feet and that there is approximately the required fall (from 61.7 to 56.1 feet) between 1,100 and 1,200 yards. If, then, a line is drawn on the map 1,100 yards from the crest line and machine-gun fire is directed from a point on the line so arrived at, at the crest line, with sights at 1,100 yards or the angle of , departure equivalent to this, plus the angle of position of the crest, the bullets will sweep the reverse slope. The above method determines the best position for covering fire and aids in selecting positions for machine guns for night fire. RANGE TABLES AND FIRING DATA. Plates 15 and 16 show two kinds of range and firing data cards in use by one of our allies. They are prepared for each kind of ammunition used. A graticule card for both classes of ammunition is also shown. AIDS IN THE DETERMINATION OF RESULTS OF FIRE. Screens of suitable size, covered with paper, are used at some of the training centers for determining the results obtained from different classes of fire. For example, if it is intended to sweep the reverse slope of a ridge or hill, several of these screens are placed along the slope to be swept and between bursts results are signaled, or after the exercise, the number of hits are counted. If there is to be practice in overhead fire, rows of these screens represent our troops at different stages of their advance and the safety angles for this class of fire are determined by sighting at the tops ol the screens. There must be no hits on these screens. Other screens represent the enemy. In the same way screens represent troops on a bridge, along a road, Dr the positions of supports and reserves, when practice is had, in 4 MACHINE &TTNS IN TRENCH WARFARE. "searehHig/ 1 otifefingiwith combined sights and -also during night firing. CONSTRUCTION OF EMPLACEMENTS, DUGOUTS. COMMUNICATION TRENCHES, ETC. At all tniininy ..ni<-r- aBectionof a > ' At hiaohine- .min uiri^dcttpyi&ese enticements and are taught the routine- of i ho t renches,' vlitriag * B44rt)r periods*. They c'ntght lirinir f^rtf'tft^splac^mentsand are tau-^ht tlicir duties ]>otlv in attack arid defettee iifldea 1 cotiditiohA as : realistic y'thtey ^n 'be-iide. TAOTTOAIi TRAINING. tfe 'fc: ; -: All gttide'8isiHi 1 4ffi^*fe'^d 'fett Aoiifif c^nstant'fy p^aet selecting 'gvttf' p^iflons. liii.-s of axlvance, et<., in advance of that pomtr'-'Tlfey'SWeff'g* *tfr^a^ ttfrftW if their Belec^tidn has *^ correct - n7/ ' 0lla (>8 ^ ; ^ noijinirmmf; io .'tod TH rn directed to occupy the positions chosen 1 .' ! -The officers ! moVements, correct eifors, or suggest better methitfeW eaying^mt the movements. (2) Selection of gun position^. Daily in?trm-ii<.n should be given in the selection of gun positions. Ati dffieei-^ecoftipttnied by a range-finder servant makes The selection. The actual 1 position of the gun must te chosen from a lying position, ihe person -selecting the position raising himself on hi? elbows until his eyes are on the level of the gunner \vheu firing the gun. The officer also selects the position from which he will command the guns. The range-finder sergeant, as soon as a position has been setefte^d', make's 'a' range card for the position, entering thereon the ranges to all prominent objects. The range-finder sergeant muef hot MACHINE G-TTNS IN TRENCH WARFARE. 47 accompany the Officer so closely as to make a roiiHpifuoim target for the enemy. The office then 'selects an alternative position for each gnn, which must be capable of being reached under cover from the first gnn position, and the range-tinder sergeant then i prepares a range card for that petition. (3) Method of oring-ing: up the guns.-'*Ba'fihg ulcered a gun position, the officer signals i., i!-.-- sergeant whose squad is to occnr.i- it to join him. The position oi the .-un the <;: ;.-. me range card, and the route of "the'gtm'toJte posi-ti ..u -an* then .-riven \<-, sergeant, and he condiictefci^squa^cr.siirnali' it to its' position The ;*-:.;:: li^proactoes-^Adef 'cover to a point us near the position as possible before unpacking gun, tripod, and ammunition. 'From this pwition theseare carried forward by hand. The member carrying the tripod leads and sets it up under the direction of the sergeant. The member with the gun comes next. Then come the ammunition, spare part?, extra barrel, en . Th; packs are moved >to a tmitable covered position, if possible, out :' the direct line of fire. ! It -should not be necessarv ( ke4p ; theT& ufidet cover and to maintain communu-a- tion between them and the guns, sending notice of any' chancre in his position. (4) Arrangements for ammunition supply.- Ore:'! anention must be given to the maintenance of an adequate ammunition sup- ply. Too much ammunition must not be carried to the gun posi- tion, for in case of a retirement or a sudden chancre of position it, may be lost. Ammunition carriers-bring up limited amounts, being eare- ful not to expose themselves and thus give away the position of the gun. If the distance to the packs is great, a relay will be formed, the carrier from the pack meeting the carrier from the gnn at a halfway point. (5) Methods of communication. In training, all methods of communication should be used and prsictieed; i. o., orderlies, sema- phore, other methods of visual signaling, and telephon* Fire orders and target designations should be given habitually on the ground by these methods, and always in the lying position, so as to practice communication, as well as the habit of concealment so necessary when in the presence of the enemy. ( tntl In front of trnverte*. Barrow pit ttk. and (round wir ThU faco.lMld up Hill bftlkct work r with burlap and chlektn-lr Tin en with pebbles imide an hung on tht ir* to "regutr" thf ipproch of boiib throer at night* 1 Machine guit". T- Traverse PLATE 6. MACHINE GUNS IN TRENCH WARFARE. 65 17 5 66 MACHINE GUNS IN TRENCH WARFARE. MACHINE GUNS IN TRENCH WARFARE. 67 BOMB PROOF M.C. - EMPLACEMENT BIGHT * U FLAMK. OPCH tMPtACIMINT reOHTAt HM AHO SMJNTU poor WOK-OUT POST. ftlCHT M.C EMV WITN LOOK-OUT POST . SAP COVtRIMC REMOVE PLATE 9. 68 MACHINE GUNS IN TRENCH WARFARE. -., ISilfi // ggjsifc 111 8^ MACHINE GUNS IN TRENCH WARFARE. 69 HIDDEN M.G EMPLACEMENT .AT CROSS -ROADS IN .A VILLAGE PREPARED FOR PEFE.NCE L ^A!^ PLATE 11. 70 MACHINE GUNS IN TRENCH WARFARE. RECTANGULAR LOOP-HOLE INSIDE DIMENSIONS THIS IS STRONGLY MADE OF Z' PLANKS TO SUPPORT WtlGHT OF SANDBAGS ON TOP. SLIDING STttL PLATES CAKK ARRAN6ED AS IN OTHER LOOP-MOU.AM) ALSO A LI6HT DINGED DOOR rORBLIISDING. LOOP-HOLE BOX. A A. FIXEP STEEL PLATES ON END. . >. STEEL SLJWTSC DOOR, ARRANGED TO SLIDE TO RIGHT. [THIS MYM MAM IN TWO MUTTS TO SLIM KICHT AND LtFT.^ C.C. BATTENS TO MAKE SLIDE FOR DOOR PLATE 12. MACHINE GUNS IN TRENCH WARFARE. 71 RANGE CARDS. DEFENSE. (a) Thick line first to reference point as "orienting line." (6) Lines correct relative length. (c) Range from one flank to the other in order. (d) Mark lines accurately. (e) Describe points briefly and accurately. (/) Describe exact point from whence taken. (g) All names in block letters. Emplacement No. 6. Midway between old barn on right and small tree on left. 72 MACHINE GUNS IN TRENCH WARFARE. 73 ATTACK. (a) First take range to objective, then halfway point, then inter- mediate objects. (6) Put ranges in right-hand column. (c) Objects must be in line of advance and likely to be easily recognized when reached. (d) If possible, objective should be visible from each point taken. (e) Fill in left column with range from objective and rule through right column. 600 1DOO 1450 2000 1st objective Ridge of Gate Rendezvous. JOOO. 551. PLATE 14. 74 MACHINE GUNS IN TRENCH WARFARE. The graticule card. [To be held 18" from eye.] FOR MARK VI AMMUNITION. -200 600 -400 -1000 -800 9 -1200 -1400 -1600 -1800 300- 2000 1500 1900 The machine gunner's range and trajectory card with angles of elevation etc., for Mark VI ammunition. Culmi- Range. Approxi- mate angles of Rise in minutes. nating point of trajec- elevation. tory in feet. Yards. , 100 10 ... 200 14 ~7 300 21 6 "i" 400 27 8 2 500 35 9 u 600 44 13 6 700 56 13 9 800 1 10 12 13 900 1 23 15 17* 1,000 1 38 15 23i 1,100 1 53 16 31J 1,200 2 11 18 41 1,300 2 28 20 52 1,400 2 49 20 66 1,500 3 9 21 82 1,600 3 30 25 100 1,700 3 55 25 122 1,800 4 22 28 146 1,900 4 50 29 174 2,000 5 20 32 206 2,100 5 53 37 241 2,200 6 29 38 282 2,300 7 11 47 325 2,400 7 57 47 374 2,500 8 46 52 429 2,600 9 39 55 489 2,700 10 37 59 558 2,800 11 37 62 637 2,900 12 41 ... MACHINE GUNS IN TRENCH WARFARE. 75 Trajectory disks, illustrating the cone of fire as it will appear in over- head fire, etc., for Mark VI ammunition. Range. Diameter of disks. Height of center of disk above ground, muzzle of gun is taken as being 20 inches above ground. 75 per cent cone. 100 per cent cone. 700 yards tra- jectory. 800 yards tra- jectory. 900 yards tra- jectory. Yards. 100 200 300 400 500 600 700 800 1,000 1,500 2,000 Ft. ing. 8J 1 3J 2 2 SJ 3 6 4 4 6 5 6 6 8 10 13 4 Ft. ins. 2 3 6 5 6 6 8 10 12 14 16 24 32 Ft. ins. 5 5 8 6 10 2 10 7 9 4 5 11 Ft. ins. 6 5 10 6 13 4 14 8 14 2 12 1 7 6 Ft. ins. 8 Si 12 10 16 10 19 6 20 2 19 15 6 9 1 DEPTH OF ZONE BEATEN BY 75 PER CENT OF SHOTS FIKED FROM A MAXIM GUN. Dispersion of cone. Depth. Width. Yards. Yards. Feet. 500 150 4 1,000 70 8 1,500 60 13 2,000 50 19 PROBABLE ERRORS IN RANGING TO BE ALLOWED FOR WHEN DIRECTING FIRE. Method of ranging. Per cent of error. Extent of ground to be searched to overcome probable errors in ranging. 500 yards. 1,000 yards. 1,500 yards. 2,000 yards. Judging distance Judging distance com- bined with "key ranges" 15 10 5 Yards. 150 100 50 Yards. 300 200 100 Yards. 450 300 150 Yards. 600 400 200 Range-finding instru- ments 76 MACHINE GUNS IN TRENCH WARFARE. The graticule card. [To be held 18" from eye.] FOR MARK VII AMMUNITION. -1000 1200 -1400 -1600 -1800 _ 2000 1100 1500 1900 Mark VII ammunition. Angles of elevation. Angle of descent. Cul- mi- nat- ing point. Trajectory disk. Low- est shot 100 per cent cone below cen- ter of disk. Height of center of disk above ground. Verti- cal. Hori- zon- tal. 700 yards. 800 yards. 900 yards. 100 yards. . . 12 5 200 yards. . . 15 300 yards. . . 18 5 400 yards. . . 22 5 500 yards. . . 27 600 yards. . . 32 5 700 yards. . . 38 5 800 yards. . . 46 900vards. . . 54 1,000 yards. .135 1 1,100 yards. . 1 14 5 1,200 yards. . 1 27 1,300 yards. . 1 41 1,400 yards. . 1 57 1,500 yards. . 2 15 1,600 yards. . 2 35 1,700 yards. . 2 58 1,800 yards. . 3 23 5 1,900 yards. . 3 52 2,000 yards. . 4 24 .Feet. 11 1 10 2 9 3 8 4 8 5 7 6 7 7 6 6 1 1 6 2 2 6 3 3 6 4 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 3 5 5 8 6 9 6 11 5 11 3 10 4 3 7 2 9 1 9 10 9 8 8 2 5 1 5 8 11 11 4 13 2 13 9 13 2 10 10 6 7 0.6 1.3 2.3 3.8 6.1 8.9 12.8 17.8 24.1 32.4 42 54 69 87 108 132 161 195 lin 300 1 in 180 lin 120 lin 90 lin 67 lin 50 lin 40 lin 30 lin 24 lin 20 1 in 15 lin 13 lin 11 lin 9 lin 8 lin 7 lin 6 Heights ofti At 100 yar At 200 yar At 300 yar At 400 yar At 500 yar At 600 yar At 700 yar ajectories above line ofsiglit at 800 yards. ds... ..29 ds . 57 ds 7 6 ds .88 ds 8 9 ds 7 6 ds 4 8 75% zones: 500 yards, ?* y , d! yards, iiyd?- ; 1,500 yards, 5 :; 1,000 10' MACHINE GUNS IN TRENCH WARFARE. 77 Measurements of the 75 per cent cone, Mark VII ammunition. Range. Vertical diameter. Hori- zontal diameter. Depth of E. B. zone. Feet. Feet. Yards. 500 5 2* 220 800 8 4 172 1,000 10 5 140 1,200 12 7 112 1,500 15 10 70 OVERHEAD FIRE. (a) String and Card Method of Overhead Fire. * "tvv.-" "iffETV ANCLE ., TRENCH SUPPORTED TROOPS Safe to fire overhead until troops reach "A.' (B)TMCEHT SIGHT METHOD ENEMY 800X AimnyM** focGunnm Sight raised 400" to give safety angle of 30 minutes shown by dotted line . o University of California SOUTHERN REGIONAL LIBRARY FACILITY 405 Hilgard Avenue, Los Angeles, CA 90024-1388 Return this material to the library " was borrowed. A 000 740 048 4 Universi South Libr