-3 7// Digitized by the Internet Archive in 2007 with funding from IVIicrosoft Corporation http://www.archive.org/details/engineerinwarwitOObondrich THE ENGINEER IN WAR McGraw-Hill 5ookG3mpaiiy Puj6fi^s/iers qf3oo/^/br Electrical World TheLn^moerin^ and >fmin^ Journal En^in9€>riii^ Record Engineering News Railway A^ G azettp Ameincan Machinist Signal Lngin.tadia rods (used also as level rods), a number of metallic tapes, 50 and 100 ft.; a simple plumbing kit, twine, tracing tape (for laying out intrenchments), a demoUtion outfit (40 per cent, dynamite is the handiest explosive), a camera and simple photo- graphic supplies, a simple drafting and map reproduction out- fit, a field desk and portable typewriter for the company office, (>tc. The entire equipment is ordinarily carried in wagons divided into compartments to permit ready accessibihty. It should however be such that it can be carried on pack mules, in which case survey instruments, photo equipment and the smaller and more delicate tools such as carpenter's outfits are packed in boxes of a suitable size. Each company of engineers ordinarily includes a section of mounted men and a small pack train carrying their equipment. In very rough country, where wagon transportation is impracticable, the entire equipment would be carried on pack mules. There should be an ample supply of the more common tools (especially picks, axes, mat- tocks and shovels) so that when occasion arises the labor of other troops or of civilians can be utilized. Most of the tools and materials listed above should be carried i)y each company of engineers, but some of them will be needed only with battaUon headquarters, such as surveying equipment, lithographic outfits for map reproduction, etc. With this simple equipment the engineers can perform all the operations which will ordinarily be required of them utiHzing such materials as may be found at hand. Beyond this it does not seem advisable to recommend any standard equipment, except the regular ponton-bridge equipage. There is a large number of special tasks for which special equip- 32 THE ENGINEER IN WAR ment may be used to advantage. Such equipment should be obtained locally or sent forward from the base as it is needed. Some of it may be taken with the company, or in the division train if transportation is available and the need can be foreseen. Plows and scrapers are most useful for road work, intrenching, and many other tasks. In a civiUzed country they can be obtained in almost any locaHty. For extensive railroad work the necessary special tools must, of course, be provided. They will generally be found wherever there is a railroad. For simple railroad repairs a few claw and tamping bars, track jacks, spik- ing hammers, wrenches, hack-saws, track drills and a "jim- crow" rail bender will be sufficient. Traction and hoisting en- gines and the commercial t^'pes of .trenching machines may be used to advantage in fortification work and almost any heavy construction. They can not, of course, accompany the engi- neers in their more rapid movements, but for elaborate works in one locality they may be sent forward when needed. The battalion headquarters may carry some equipment in addition to that of the companies. Extensive survey work and map reproduction should preferably be under the immediate charge of the battalion commander; the equipment therefor, especially Uthographic (zincographic) outfits being with battahon headquarters, operated by special skilled men. For rapid communication between the separated portions of an engineer command, engaged in section work at various locali- ties, a small micro-telephone outfit and a few bicycles should form part of the company equipment. All engineer officers should be mounted. The development of the motor truck will greatly increase the efficiency of engineer troops, making possible the more rapid transportation of tools and materials. It has also made possible the transportation of small, compact gasoline power plants, which may have a wide field of usefulness. Up to the present time few such plants have been developed, inasmuch as the present war is the first in which the automobile has been ex- TOOLS AND EQUIPMENT EMPLOYED 33 tensively employed. Amongst the possible gasoline power plants for military purposes are the following: Portable search- lights, winches, hoists, pile drivers, drills and boring machines, saws, trenching and mining apparatus, concrete mixers, stone crushers, etc. Very httle has been done along these Hnes and there is room for great improvement. Mihtary field engineering, as we have seen, is an adaptation of civil engineering and, in practice, differs from the latter insofar as it is governed by different economic principles and conducted under different conditions. Fortification works executed in time of peace are essentially similar to civil engineering construc- tion, and the same is true of many engineering operations con- ducted in time of war on the lines of communication in rear of the fighting forces. On such works, civihan engineers without military training may often be employed to advantage. We are now concerned, however, with field engineering, the pioneer operations of the fighting forces. Here we find a sharp contrast with civil practice. The conditions which govern the mihtary pioneer may be recapitulated as follows : 1. All works must be designed and executed to meet actual tactical needs. If constructed without due regard to the tactical situation they may be worse than useless. 2. A very large proportion of the works will be constructed to meet sudden emergencies. Opportunities to plan and carry out works a consider- able time in advance of need therefor will be comparatively infrequent. 3. The fundamental economic principle of military engineering is that time is of the essence. Cost and durability of works are ordinarily matters of minor importance. The quickest makeshift is usually the best solution. 4. Simplicity must characterize all designs. 5. Materials which are available at or near the site of the work must be utilized to the fullest possible extent. 6. There will usually, but not always, be ample common labor available, but a dearth of skilled labor of all classes. 7. As a rule, no heavy construction plant and only the simplest tools and materials will be available. The works resulting from these conditions are of a very simple nature. The highest expression of the skill of the mihtary engi- 34 THE ENGINEER IN WAR neer is this very simplicity, and the rapid adaptation of his de- signs to the tactical requirements of the situation and to the resources in men, tools, materials and the time at his disposal. The following brief summary of some of the more usual and important operations of the military field engineer will serve to illustrate the principles hereinbefore enunciated. CHAPTER IV STREAM CROSSINGS The ability to cross streams is essential to the mobility of the army and to facilitate such passage is one of the chief duties of the engineers. The history of war is replete with examples of delays and failures due to the lack of equipment for the rapid construction of bridges. On the 26th of January, 1814, Napoleon writes, "If I had had 10 pontons, I should have captured 10,000 wagons, beaten Prince Schartsenburg in detail, annihilated his army and closed tlic war; but for want of proper means I could not cross the Seine." Writing to the Adjutant General under date of May 18, 1846, (lenoral Zachary Taylor says: **My very limited means for crossing rivers prevented a complete prosecution of the victory of the 9th (Palo Alto). A ponton train, the necessity of which I exhibited to the department last year, would have enabled the army to cross on the evening of the battle, taken this city, with all the artillery and stores of the enemy, and a great number of prisoners — in short, to destroy entirely the Mexican Army." BRIDGES The passage of streams is so very important and necessary that the mobile army can not afford to rely entirely upon make- shifts improvised from materials collected at the site, as the above quotations will show. Indeed, in the case when a large army with its heavy trains is confronted with a wide and deep cross- ing the construction of an improvised bridge might require weeks 35 36 THE ENGINEER IN WAR STREAM CROSSINGS 37 (f time. The shifting tactical requirements do not wait on ach delays and to meet such situations some form of portable ridge with floating supports is absolutely necessary. Ac- cordingly, all modern armies carry such bridges which are known as ponton equipage. The equipage in use in our army was devised prior to the civil war and used with conspicuous success throughout that great conflict. It is a tribute to the wisdom of those who de- vised it that in over fifty years no radical changes have been made. The equipage is one of the simplest and most cunning of military expedients. I ^^r^ FiQ. 4. — Trestle span of portable bridge equipage. There are two forms of the equipage, known as the heavy and light. In the heavy equipage the supports or piers are wooden boats called pontons (Figs. 2 and 3). They are 31 ft. X 5 ft. 8 in. X 2 ft. 7 in., weigh 1,600 lb. and have a displacement of 93^ tons each. For the shallow portions of the stream, portable trestles consisting of two legs and a cap, which is held in position by wedges, are provided (Figs. 4 and 5). The roadway is supported by stringers or balk of white pine, 27 ft. long and 5 in. square. The number of balk in a span varies from 5 to 11, according to the load to be carried. In the first boat the balk rest on a saddle in the middle, which forms a hinge to allow for changes in 38 THE ENGINEER IN WAR the level of the water (Fig. 11). In the other boats the balk rest on the gunwales. All fastenings are by means of lashings. The deck consists of plank IJ^ in. X 12 in. X 13 ft. of white pine, called chess. They are held in position by side rails laid on the deck at its edge and lashed at intervals to the balk be- low, the lashings passing through notches in the plank (Fig. 5). The pontons are held in position by a system of upstream and downstream anchors. The distance from center to center of supports is 20 ft. Fig. 5. — Portable trestle bridge of regular equipage. Note abuiim-iii .sill, balk and side-rail lashings. This bridge can be constructed in a few niiiiute.s. It will carry the heaviest loads which accompany the army. The light train is similar to the heavy, except that the ponton boats consist of a framework covered with heavy waterproof canvas and can be dismantled for transport (Figs. 0, 7 and 8). They have a buoyancy of 6 tons, the balk are shorter and lighter, the span between supports is 16 ft., and the roadway narrow(^r. The two trains may be combined in one bridge. This material is all transported on wagons (Figs. 3 and 7) and is sufficiently mobile to accompany the troops on the march. STREAM CROSSINGS 39 i 1 1 40' THE ENGINEER IN WAR The light train can keep pace with cavah-y. The roadway will support the heaviest loads that accompany the army with a factor of safety of four., This bridge can be laid, crossed and taken up in far less time than any other form of bridge ever devised can be constructed. The weight of the heavy equipage, including the wagons on which it is carried, is 315 lb. per running foot of bridge; of the light equipage, 275 lb. Not including wagons, the weights are 169 lb. and 128 lb. respectively. It will be interesting to compare these weights with those of other forms of bridge of equal capacity. Fig. 8. — Assembling the canvas ponton. There is a regular routine for construction and so wonderfully simple is the equipage that unskilled men can be taught to use it in a very short time. The bridge may be constructed by pushing out successive pontons from one or both banks (Figs. 9 and 10) by constructing parts along shore and floating them to position, or by constructing the entire bridge along the bank and then revolving it into position. The first method, known as "successive pontons" is the one usually employed. The procedure, as laid down in the "Engineer Field Manual, U. S. STREAM CROSSINGS Side Rails - Balk Chess _X r Fig. 9. — Constructing bridge by successive pontons. Fig. 10. — Constructing bridge by successive pontons. Two trestles are placed, and the first ponton with saddle m center is in position. 42 THE ENGINEER IN WAR Fig. 11. — Completed bridge of heavy equipage. Note saddle in first boat. Fia. 12. — Completed bridge of light (canvas) equipage. STREAM CROSSINGS 43 L.... ^fterpendicular to the bridge axis and secured by pickets, two at ISach end (Fig. 5). If necessary, one or more trestle spans are then placed and the first floating support is brought to the bank opposite the abutment. The free ends of cables fastened to the bank 30 paces above and below are passed to men aboard the ponton. A set of balk is brought up and the cleats engaged l^ki the saddle of the ponton and lightly held by lashings. The Fig. 13. — Draw span in ponton bridge. (Spanish ponton equipage.) ponton is pushed off until the cleats at inner end of balk engage the abutment sill and the mooring lines made fast. The balk are then lashed securely to the saddle and the chess (deck plank) laid. The next ponton is then brought alongside and its anchor lines (previously placed by another boat) passed aboard. The operations are repeated until the other shore is reached. The bridge is dismantled in reverse order (Figs. 11 and 12). If the bridge is to be in position for some time a movable section 44 THE ENGINEER IN WAR or draw may be placed in the middle to allow the passage of vessels, drift, etc. The draw consists of two boats with a span of decking between (Fig. 13). The construction of these bridges is one of the most pic- turesque and interesting of military operations. The adaptability of the equipage is very great and improvised floating supports, such as boats, rafts and casks, may be used to supplement the regular equipment. An indication of the astonishing capacity and speed of con- struction of which the ponton equipage is capable is afforded by the following historical example : In his attempt to reach the south side of the James River for the attack on Richmond in 1864, Grant decided to throw a bridge across at Fort Powhatan, near Charles City. The approaches were built on June 13th. The floating equipage was brought up from Fort Monroe on June 15th and the bridge was laid between 4:00 p.m. and 11:00 p.m. of that- day. It was built from both ends. The bridge was 2,200 ft. lo^ and 101 wooden pontons were used. The depths were so gr^t and the current so swift that several schooners were moored in the river to carry the upstream cables of the bridge. In a letter to the Chief of Engineers, Gen. Benham, who constructed this bridge,, says : "... I presume you will be glad to hear of the success of our ponton bridge, over 2,000 feet long, over the James River just above Fort Pow- hatan, which I had placed there on the evening of the 15th. . . . About 11 : 00 a.m. on the 15th I received the order, and was under way in half an hour, arriving at the position selected at about 5: 00 p.m. Therp I found Gen. Meade and Gen. Weitzel, which latter had prepared the approaches and had the abutment commenced. I was at once directly charged with the laying of the bridge by Gen. Meade with the regulars to assist the volunteers, and he smiled when I told him I should not sleep till the bridge was laid. "I distributed my men at once, the regulars at the east end, the volun- teers at the west end, and a company of volunteers to prepare a raft by my plan of simultaneous bays. I STREAM CROSSINGS 45 "At about 10:30 p.m. I received a dispatch from Gen. Meade asking the progress of the bridge, to which I was able to reply at once that the last boat was in position, and the raft of three boats built ready to close the gap he had ordered left for the present, and that it was ready for completion in fifteen minutes at any time he ordered. . . . " For the next forty hours after 6 a.m. of the 16th, a continuous stream of wagons passed over the bridge (from 4,000 to 6,000 wagons), some said fifty miles of wagons — and nearly all the artillery of this army, and by far the larger portion of the infantry and all its cavalry present, and even to its herd of 3,000 or more of beef cattle (the most injurious of all) without accident to man or beast. "My officers and men were scarcely allowed any sleep during this time nor myself as much as four hours in the eighty hours preceding the tak- ing up of the bridge, for it was in anxiety, not to say trembling, that I saw the destinies of the whole army of our country even committed to this single, frail, boat bridge, with steamers and other boats drifting against it and with much of its planking previously worn almost entirely through by careless use upon the Rappahannock, and I dared not stop the living stream of men or matter to sheath or protect it. "At length by 7 a.m. on the 18th, the last animals were over and I breathed free again, and although the shelling of our troops across the river just before sunset within a mile above us gave us little hope of withdrawing the bridge in safety, it was ordered up and all rafted into three tows before 3 a.m. of the 19th, and on its way to this point, which it reached about sunrise, the most successful effort on a large scale with ponton bridging that has ever occurred in our country, if it does not rival those in any other land. . . . "You may be sure I was very well content and satisfied and felt like 'him that putteth off his armor,' when the affair was over." This is an interesting chapter in the annals of bridge en- gineering. While great reliance will be placed upon the ponton equipage, it can not entirely obviate the necessity for hastily constructed bridges of other tjrpes, which must frequently be improvised from materials found near the site. Such bridges are known as ''bridges of circumstance." Considerable skill on the part of the engineer officers will be required to adapt the bridge to the 46 THE ENGINEER IN WAR site and materials available to produce the quickest results. The construction of a bridge is an interesting task, and there is a strong tendency to put in a bridge when a reconnaissance a little up- or downstream would have revealed a practicable ford, or to build a bridge at a site where an improved ford with suitable approaches would have served the purpose at a far less expendi- ture of time. The engineer confronted with a stream crossing seeks first a practicable existing bridge and in contemplation of a movement Fid. 1 1. — Siini)l(' pile tre.-jtle. of troops all important bridges that may be used should be seized in advance to prevent destruction by the enemy or his sympa- thizers. Even if the bridge is insufficiently strong or has been damaged it can often be repaired or strengthened in less time than a new bridge could be built. The number of types of these improvised bridges is naturally very great, but a few of them have been found especially adapted to military uses. STREAM CROSSINGS 47 I pr The most common type is the simple two-legged trestle, frame or pile, which can be adapted to a great variety of condi- tions. The relative time and difficulty of constructing the piers and spans will fix the economic length of span. For military purposes this will usually be 10 to 15 ft. and for such a span longi- tudinal bracing will usually be unnecessary (Fig. 14). But if the water is very deep or the banks high, so that large trestles I'lG. lo. — Driving })ilob with portable driver. The float is of ponton equip- age, and the hoist is operated by a gasoHne engine. are required, it will often be better to reduce their number and increase the span, employing more stringers or some form of hght truss. To reduce the size of trestles the approaches may be cut down. In selecting a site the time of construction for bridge and approaches should be considered. Ordinarily a locality where the stream banks are low and firm and of equal height with a short span will be the best site. If the depth be 48 THE ENGINEER IN WAR moderate and the bottom firm the framed trestle will be best. If necessary a mud sill may be used to increase the bearing power and, if the depth is considerable or the current swift, the trestles may be weighted down by boxing their sills and filhng with stone. While the two-legged trestle is the favorite type, three or four- legged (sawhorse) trestles may be employed. Cross bracing Fig. 16. — Portable pile driver with swinging leads and gasoline hoist. of trestles is always necessary and for long spans longitudinal bracing may be required. For very high trestles, two or three stories may be used. Almost any materials can be utilized for trestle bridges, even bamboo has been successfully employed to carry heavy loads. In considerable depths with a soft bottom pile trestles are often to be preferred. A hasty pile driver may be improvised with a heavy block of wood raised by tackle and STREAM CROSSINGS 49 guided by a "spider" and a few upright poles. Of course a light portable power driver or hammer will be very useful in such situations if available (Figs. 15 and 16). For very soft, yielding bottoms, especially if suitable piles are not available, simple log cribs filled with stone, if necessary, may be employed in conjunction with trussed spans. Material suit- table for cribs is usually easily obtained and handled. ^-««^ ^E mB ^^H ^B Fig. 17. — Truss bridge constructed in field by engineer troops. The spans are 90 ft. and the roadway 16 ft. The purpose of trusses is to reduce the number of supports. In military field operations the use of trusses will usually be hmited to situations where they can be placed with the aid of animals and tackle and without false-work. If it be necessary to place false-work, this will usually serve to carry the deck and no truss will be needed. If the bridge is to be used for some time and there is danger from flood or ice, large trusses may be placed. Such work would seldom fall to the lot of the pioneer engineer 50 THE ENGINEER IN WAR troops. An excellent example of a large military truss bridge is that built over the Kansas River at Fort Riley, Kans., by the 3d Battalion of U. S. Engineers, and described in Engineering Record, July 11-18, 1908 (Fig. 17). The usual forms of truss will be the simple king-post (or triangular truss) and queen- post, erect or inverted, with tension members of iron rods or steel cable. Small Howe or Pratt trusses and lattice or bow string girders of plank spiked together are often employed Fig. 18a. — Simple trusses. (Figs. 18a and 6). The difficulty of placing trusses without tho aid of plant ordinarily limits their span to about 40 ft. the larger trusses being built in place when practicable. Under special con- ditions, as where the truss may be floated to position on a barge, greater spans may be practicable. In many situations the spar lock bridge, which in double lock is practicable up to 45-ft. span, may be constructed more easily and quickly than a truss. The supports of this type consist of two tall trestles erected on or near the bank and tilted over STREAM CROSSINGS 51 >7^ ^T ELEVATION FiQ. 186. — Simple trusses. 52 THE ENGINEER IN WAR until their heads lock amidstream, forming a point of support. This is called single lock. In double lock the trestles are tilted until they lock with a frame placed between them, this frame forming one central span. This type has pecuhar advantages from the mihtary point of view as, where applicable, it can be very quickly constructed of the roughest materials (Figs. 19, 20 and 21). Clear spans of more than 50 ft. should usually be avoided by seeking a more favorable site. When such can not be found a suspension bridge will usually be the only type which will meet i>f<^y Fig. 19. — Spar bridges. mihtary requirements and, for moderate loads, is practicable for long spans. The essential part of a suspension bridge is the cables, and if these are available, the balance of the material is usually readily obtained. A great variety of materials have been employed for cable including manila rope, chains, bamboo, etc. The best material for cables, of course, is wire rope, and when the necessity for such bridges is possible a supply of rope with fittings should be carried by the engineers. Adjustable sus- pension rods or hangers may also be provided in advance — cable will serve this purpose. On account of the difficulty of STREAM CROSSINGS 53 handling and fastening large cables they should be Hmited to ^ in. or 1 in., multiple cables being used when necessary. The first step in construction is to erect the towers and prepare the anchorages for the cables. The towers will usually be of timber and of the sawhorse trestle type, to resist overturning both during construction and subsequently, as no roller bearings are employed and vertical reactions can not always be insured. 1 1 '''■ -^ — 1 m ^ i»r. m ^ • . TT ?Kt^S3 1 if m ^m\ / ♦ i j^^®5^ N W ^-^ jiSiJ^i'^'' ! > i__j — Fia. 20. — Double lock spar bridge. Standing trees may occasionally be utiUzed for towers. The anchorages consist of large logs in trenches (deadmen), standing trees or stumps, large boulders or ledges of rock, where available. Occasionally concrete is employed. The cable may be dragged across the towers or laid out, measured and anchored (tem- porarily at one end to allow adjustment) on the ground and then lifted to the towers. The sag of the cables will usually be con- siderable. This decreases the strain on the cables but makes 54 THE ENGINEER IN WAR the bridge very liable to undulation under live loads. Slings or suspension rods may be cable, wire rope, manila rope, round iron, or even wood. From each pair of slings hangs a transom or road- way bearer, on which the stringers and deck are placed (Figs. 22 and 23). Fig. 21. — Double lock spar bridge with suspended roadway. are lashings. All fastenings Oscillations and undulations may be controlled by lateral trussing of the roadway, by a trussed guard rail, by drawing the cables together at the center of the span, and by guys. In many situations a combination of types meets requirements better than any single type. Such combinations might include I STREAM CROSSINGS 55 KiG. 22. — Field suspension bridge, roadway of ponton material. waKon is the stanthinl engineer tool wagon. The ^M - "^ ^ m Fig. 23. — A Spanish suspension bridge in the Philippine Islands rebuilt for military use. Only the towers of the old bridge remained. 56 THE ENGINEER IN WAR frame and pile trestles, trestles and truss spans, a combination of trestles and floating supports, the latter being a very usual expedient. The deck or roadway should be no wider than necessary, both because of the weight and extra time required for construction: Ordinarily two lines of vehicles will not be passing in opposite directions at the time same. Twelve feet is usually quite sufficient for a wagon bridge, allowing for the passage of foot or horsemen alongside the wagons. For a foot bridge alone a less width is required. Side rails are always provided but hand rails are seldom used except on through truss and suspension bridges. The stringers may be of round or sawed lumber. Planking IJ^ in. or more in thickness makes the best deck. Where this is not available the deck may be of poles held in place by side rails and covered with brush, leaves and earth or gravel. This makes a satisfactory deck but, except in short span trestle bridges, is objectionable because of its weight (Figs. 19 and 20). The fastenings are of the simplest nature, lashings, spikes and bolts being used. Elaborate framing is avoided as far as possible. FORDS Before entering upon the construction of a bridge search should be made for a practicable ford, if the nature of the stream gives any promise that such may be found. Fords which have been used by the local inhabitants should be first examined. In determining the practicability of a ford the considerations are: (a) nature of approaches; (6) nature of bottom; (c) depth of water; and (d) velocity of current. For the passage of mounted troops and wagons the approaches may be improved by cutting down the banks to ease the grades, and by surfacing the roadway with plank, brush, gravel, etc. A sandy bottom is the most favorable and usually requires no improvement. If the bottom be rocky or yielding it may be made practicable by a deposit of sand or STREAM CROSSINGS 57 •avel, by fascines or bundles of brush, or by a woven mattress ink in position. The limiting practicable depths of fords where the current is sluggish are: for infantry, 4 ft.; for cavalry, 5 ft.; for artillery or wagons, 2}4 ft. If the current is swift the depths For infantry and cavalry are 3 ft. and 4 ft. respectively. A hfe ine may be stretched across the stream to facihtate the passage of infantry. Ice 2 in. thick will support infantry in single file; 4 in. thick, cavalry at intervals; 5 to 6 in. heavy field pieces. Lundiiig wharf and pile driver of pun tun material. FERRIES When fording is impracticable and there is not time nor material for a bridge, resort may be had to a ferry. These will be used especially in cases of wide crossings, where time is of special importance and when the number of troops to cross is small. The ponton equipment heretofore described is specially designed with a view to its use for ferrying purposes. The pontons of the heavy train will carry from 20 to 40 foot troops, in addition to the crew. A raft or catamaran made of two pontons with a span of flooring between will carry cavalry, artillery and wagons. In the absence of the ponton equipment rafts may be constructed of logs, casks, etc. 58 THE ENGINEER IN WAR If the current be swift a rope may be stretched from bank to bank and the float drawn across by hand. Or the current may be made to furnish motive power by attaching a block to the rope and securing the float to the block in such a manner as Fig. 25. — Trail ferry and landing of ponton equipage. to hold it at an angle to the current. In the flying bridge the float is attached to and swings in a circle on a line anchored well upstream. The current may be made to furnish motive power, as in the former case, or the ferry may be drawn across by an auxiliary line secured to the bank (Figs. 24, 25 and 26). STREAM CROSSINGS 59 Fig. 26. — Flying ferry. 60 THE ENGINEER IN WAR EXAMINATION AND REPAIR OF SIMPLE HIGHWAY BRIDGES An important problem with which the military engineer will often be confronted is that of determining the supporting power or safe load of an existing bridge, and the methods that may- be adopted to strengthen the structure. Good civil practice has resulted in the adoption of type plans for the various forms of bridges, the safe loads of each being carefully specified. Commercial traffic is usually heavier than that which accompanies the mobile army and accordingly a well-designed bridge may generally be pronounced safe for military use, provided an examination shows that it is in good condition. Also the factor of safety may, in such a case, be reduced from 5 or 6 to 2} '2 or 3, if this be necessary. But in our country we encounter many bridges which are not designed in accordance with good practice. Many of them arc not designed at all, and in many steel bridges economy of material is carried to an extreme, the designers trust- ing in Providence that the bridge will never be tested to the specified loading. The quickest method of determining the carrying capacity of a bridge is by comparing it mentally with other similar bridges whose capacity is known. This will require considerable expe- rience and great power of observation on the part of the engi- neer. To calculate accurately the carrying capacity of a bridge may be a tedious operation, but approximate methods or "rules of thumb," which any competent engineer can devise for him- self, will usually give results sufficiently close for practical purposes. An examination of the bridge by an experienced engineer will usually serve to indicate the weakest or critical parts of the structure, to which special attention should be given. A useful formula for bridge stringers of wood, such as are often encountered, is the following: Safe center load in pounds times span in feet equals A times BD^. In this formula A is a factor depending on the kind of wood, and B and D are the breadth and depth of the stringers STREAM CROSSINGS 61 in inches. For a factor of safety of 3, A may be taken as at least 100 even for rather poor timber. Hence, if a wooden fstringer is to be safe, BD^ should equal the span in feet times the W jenter load in hundred weights, BD^ X L X y^^. The weight )f the beam itself may be disregarded. The safe uniform load may be taken as double the safe concentrated center load. [If the deck is sufficiently heavy the equivalent center load on any one stringer should not exceed about 30 per cent, of the weight of the army wagon or artillery carriage. Under this assumption the rule gives the following: For loaded wagons or light artillery, BD^ = or > 20 X span. For heavy field artillery, 4.7 in. guns, BD^ = or > 30 X span. If the span is less than 15 ft., the span multipliers may be re- duced one-third. A convenient rule of thumb for the deck, if of wood, is that the thickness of the deck in inches should be as great as the in- tervals between stringers in feet. Thus, if the stringers are 3 ft. apart the decking should be 3-in. planking. If the stringers are standard steel I beams their safe loads vary approximately with the square of the depth. Also the fiber strength is about 10 times that of wood. Hence the rules become for long spans: For loaded wagons, D^ = or > 2 X span. For heavy field artillery, 2)^ = or > 3 X span. These rules are but rough approximations, but they serve for practical purposes, and afford a test of the strength of the floor system. If this be safe the remainder of the bridge timbers are probably right, since good design demands this condition, and the floor system is most subject to wear and decay. However, similar approximations may be applied to trestle caps of two-legged trestles or the roadway bearers of small truss bridges. Assuming the weight of a bay with its load at 20,000 lb., we have, BD'^ = or > 100 X length of caps; or for steel I 62 THE ENGINEER IN WAR beams, D^ = or > 10 X length of beam. For spans of less than 15 ft. the multipliers may be reduced by half. The strength of simple Howe or Pratt trusses may be quickly determined by the well-known method of ''shear and chord increments." These rules are applicable to structures which closely follow standard design for the types considered and to the usual loads with the army. Any bridge which exhibits a radical departure from the -usual designs should, in the first place, be looked upon with suspicion and, in the second place, should be examined with more than ordinary care. If unusual loads are to be brought upon the structure a more thorough examination is, of course, demanded. If the deck planking is thin, worn or decayed, longitudinal planks may be laid under the wheels. A weak stringer may be braced by placing a post under its center, or a trestle or crib may be inserted at the center of the span, which supports all the stringers. Sometimes it will be easier to take up the flooring and insert additional stringers. If trestle legs are over 10 or 12 ft. in length they should be cross braced, and if the spans are over 15 ft., the trestles should be braced longitudinally. Wooden trusses may be strengthened by spiking or bolting additional timbers to the chords and inserting web members of timber. A weak steel truss may be supported by one or more trestles or cribs inserted beneath. These are but a few of the expedients that will suggest them- selves to the resourceful engineer. It will usually be easier to reinforce an old bridge than to build a new one. A bridge which has been examined or strengthened should be placarded to indicate its safe load. CHAPTER V MILITARY ROADS We have seen that mobility, the power to maneuver in stra- tegical and tactical combinations, is essential to success in military operations. Roads accordingly play an important lolc in the conduct of war. In modern warfare, with the vast number of combatants engaged and the great extent of territory covered, roads will be of more importance than in the past. While miUtary operations of any magnitude will be dependent kupon the railroads yet the motor truck has become a most important aid to the railroad in the transportation of troops, jfcrtillery and material of all kinds. To realize the advantages Ihat may be derived from its use an extensive system of good roads is essential. Good roads saved Paris from falling into the hands of the Germans during the present war. It was the steady stream of soldiers poured into the firing line by automobiles on the magnificent chaussies of France that turned the tide of invasion at the Marne. In road work, probably more readily than in any other branch of military field engineering, the engineer with civil training can adapt his knowledge and experience to war conditions. Military road building is similar in many respects to civil prac- tice. The civil engineer who has a thorough knowledge of the methods that produce good roads and the broad common sense which will enable him to apply them to military needs will be successful in time of war. It is only necessary that he should thoroughly appreciate the economics of warfare which we have heretofore discussed. Motor transport demands good roads and even for animal transport they are to be desired. The construction of a modern 63 64 THE ENGINEER IN WAR paved highway takes time and therefore military operations will be greatly hampered if they are conducted in a country which has not been provided in time of peace with a complete system of good roads. In many parts of Europe such systems exist and the principal highways have been built with a view to their usefulness in war as well as in peace. The United States is poorly equipped both as to the quantity and the quaUty of its roads. In any mihtary operations conducted in our terri- tory, extensive road construction must be carried on by both combatants. Military road work will consist very largely of the improve- ment, repair and maintenance of existing roads, but in many of our possible theaters of war, including the United States and other parts of the American continent, extensive new con- struction work will also be necessary. In the location and construction of a military road the peculiar economics of warfare, which have been heretofore mentioned, should be kept constantly in mind. In the construction of a civil road or railroad the amount of money which may be prof- itably expended in reducing grades, securing good alignment and in paving (in the case of a road) is determined from the estimate of the nature and amount of the probable traffic. In military construction the element of cost is of secondary importance, but the question of time is paramount. The road must be opened for traffic in the least possible time. Nevertheless the nature and amount of the traffic and the period during which the road will probably be required are not, of course, entirely disregarded. The road will usually be constructed to meet the exigency of the moment and may later be altered and improved to meet the development of the situation. Common labor will ordinarily be plentiful, but often no plant at all will be at hand. Wlieelbarrows can usually, although not always, be suppUed, and for extensive work plows and drag or wheel scrapers should be obtained. Explosives will be available and may be Uberally employed. The use of more elaborate MILITARY ROADS 65 plant, such as graders, steam shovels, etc., will seldom be practicable or advisable under war-time conditions. The stretches of road to be con- structed will usually be relatively short and built to connect exist- ing roads. Motor trucks will be utilized on the good existing loads where they can move at the relatively high speed which is necessary if their economical advantages are to be realized. lUit on purely military roads l)uilt under service conditions iimch of the traffic especially in our own operations, will be by wagons drawn by horsos or mules. Four and six line teams may be and are employed in miUtary operations when civil economics would demand two line teams (Fig. 27). Also, military traflfic moves in trains and teams may be doubled up and loads shifted when neces- sary. Extra teams and relay stations may be provided. Such traffic moves but slowly on the best roads, and hence the greatest improvements in the road will effect only slight changes in the speed of trans- port (though they may reduce its cost), unless motor trucks be substituted for wagons. A rough either 66 THE ENGINEER IN WAR surface, if firm, is of little disadvantage to slow-moving trafl&c and the same is true of poor alignment, though, of course, very- sharp curves should be compensated by widening the road. Brick roads are, of course, out of the question, except possibly along the main motor routes on the lines of communication. For wagon traffic their advantages are not sufficient to justify their cost and, more particularly, the time required for their construction. Even common water-bound macadam can seldom be advantageously employed. The military road will usually be a common earth road. If the soil is very saijdy it may be mixed with clay for a wearing surface, and conversely. Gravel Fig. 28. — Road improved for military use by paving of logs and brush. Constructed by the Germans in Russia. may occasionally be used to good advantage if it can be obtained along the hne of the road. Pit gravel usually compacts very satisfactorily under traffic if shaped up occasionally. Stream gravel usually requires the addition of a binder. If the gravel contains many large pebbles or stones it should be screened. If stone is available a rock fill covered with a layer of earth may be emploj^ed at soft spots where the drainage is bad. In swampy or poorly drained ground a plank or "corduroy" road will usually be the simplest and best expedient. The logs or poles are seldom covered, and the surface, while rough, is firm and suitable for MILITARY ROADS 67 slow-moving traffic. A great variety of materials may be used to temporarily increase the supporting power of a roadbed, including branches of trees, bunches of brush, grass, turf, leaves, etc. It is to be remarked that the advantages of very low gradients can not be fully realized unless a good surface is also provided and, conversely, the advantages of a good surface can not be fully realized unless the grades are held down. Accordingly it is of little use to strive for very low grades on a road which is not to be paved, or to incur great expense of time and money in provid- ing a macadam paving on bad grades. A good macadam road must have low grades. Also, for slow-moving military traffic neither low grades nor good surfaces are as advantageous as for motor transport. Military traffic moves in trains and its use of the road may be regulated. Loaded wagons generally move in one direction only and empties in the opposite direction. Under these conditions a 10-ft. or even an 8-ft. width of road may be made to meet requirements, passing points being placed at the necessary inter- vals and where the extra width may be cheaply provided. Such a narrow road would, of course, be very unsatisfactory for un- regulated civil traffic with loaded wagons passing at random in both directions and meeting at all points. A width of 16 ft. which permits the easy passage of two lines of wagons in opposite directions, is desirable if it can be obtained without excessive excavation. It will seldom be advisable to provide more than an 8-ft. width of metal if the road is to be paved. In the location of a military road the foregoing facts must be borne in mind. In order to reduce the excavation to a minimum the road should lie close to the natural surface of the ground, even if this results in occasional steep and adverse grades, poor alignment and consequently increased length. Heavy cuts and fills with the great yardage and the relatively long hauls which they involve should be avoided. A gradient generally not exceeding 4 to 5 per cent, with occasional short maximum 68 THE ENGINEER IN WAR stretches of 6 to 7 per cent, may be regarded as quite satisfactory for military wagon transport if better grades can not be secured without excessive labor. A road having a grade generally not exceeding 8 per cent, with occasional maximums of 10 or 11 per cent, or even more, will be practicable, but will require relay- ing if the distance be considerable. It may be adopted if the nature of the terrain does not allow better natural grades. Adverse grade should, of course, be avoided, even if this requires more distance. In the original location an effort should be made to keep the grades generally as moderate as the nature of the terrain will permit without excessive excavation, and to concentrate the steeper grades in a few localities. The road is thus opened up and the had grades may later be reduced if neces- sary by cuts and embankments. By thus concentrating the un- favorable grades in a few localities subsequent improvements may be effected with the least possible relocation and interrup- tion to traffic. Thus if there is a possibility that the road may be used for transport for a considerable period it will usually be better to adopt a general grade of about 4 per cent, with oc- casional sharp maximums 8 to 10 or even 12 per cent, rather than a general grade of 7 to 8 per cent, with nothing exceeding this. In the former case a few relocations in the maximum sections, involving perhaps some heavy excavation, will even- tually produce a good 4 per cent, road, whereas if the steeper general grade were adopted, complete relocation and reconstruc- tion would be necessary to produce the same result. In the first instance the heavy work is avoided by a steep chmb or a detour which is later ehminated and abandoned. Thus the locator should consider what may eventually be required and so plan his original location as to enable the ultimate requirements to \}v met with the least possible reconstruction, even at the cost of temporary disadvantage in the way of occasional very steep grades. If the future requirements are uncertain it may be ad- visable to adopt a somewhat higher general grade, suited to the nature of the terrain and to avoid steep maximums greatly in I MILITARY ROADS 69 excess of the general grade. It will be apparent that the problems of the military locating engineer are not greatly different from those of his civilian confrere. He must consider the demands of the immediate situation and meet them promptly, but so far as practicable he should also give consideration to the ultimate requirements. In locating a road for military purposes the engi- neer enjoys one great advantage in that he is not hampered to so great an extent as the civiHan by questions of right-of-way, property values, etc. And, as in all military construction, first cost gives way to speed, which often simplifies the problem. The general location of the road is selected from a map, if one suitable for that purpose is available. The next step is a hasty reconnaissance or preliminary survey to fix the general location on the ground, determine the grades which may be ob- tained and the special difficulties to be encountered, the materials available along the route, etc. For this examination very simple instruments will serve, an aneroid barometer for elevations, a luiiul clinometer to measure gradients, distances measured by pacing. A rough sketch of the route should be prepared and it 'should be marked out by placing flags (pieces of red cloth on sticks), blazing trees, etc. The detailed location may be satis- factorily executed with the same instruments in the hands of skillful and experienced men. A fight transit with a vertical limb and a tape or stadia rod are better and will usually meet the roquirements. The removal of trees, especially their stumps, is a slow process and it is therefore well to avoid timbered areas if practicable. Also, the absence of sunUght and poor ventilation increase the difficulty of maintaining an earth road in a wood in passable condition. If it be necessary to pass through a wood the road may be curved or zigzagged to avoid the very large trees. The best way to remove a large tree is to dig around it, cut the larger roots and then pull over the tree with blocks and tackle. This removes tree and stump. If stumps are encountered they can be removed only by explosives which may be used fiberally to save 70 THE ENGINEER IN WAR time. For military purposes a wooden trestle or viaduct, which may be constructed in a few hours or a few days, is often pref- erable to a long high embankment which may require weeks to construct with inadequate plant, and will generally also have to be paved in some manner to render it passable. Skill in location will reduce the number of culverts required, often it is true, at the expense of alignment. The road should follow the high ground or ridges, and the side ditches may be led off into adjacent ravines. Also, sun and air are very important aids in the maintenance of an earth road. Culverts when employed should be of the simplest type, plank and corrugated iron pipe being the most suitable materials and sufficiently durable for military purposes. The bearing power of a road surface depends upon the paving and upon the drainage of the roadbed. Military roads will seldom be paved and according!}' particular attention should be 'given to drainage. Sub-drainage will usually be imprac- ticable but ample side ditches should always be provided, except in very dry climates. The material from the ditches is used to raise and crown the roadbed. The best form of ditch is one wide and shallow rather than narrow and deep, since it is more easily constructed and kept open. Such a ditch may be constructed with a drag scraper, with a plow to loosen the earth. If the road is constructed on a steep sidehill, surface or intercepting ditches may be provided to keep the water from the hillside off the road. Retaining walls should be avoided if possible, as they require much time to construct. Zigzags or switch-backs may be employed to save labor on sidehill work. Retaining walls if used are built of log cribs, dry rubble, etc. Concrete will seldom be employed. One of the economic advantages of a well-paved road from the civil engineer's point of view is the decreased cost of main- tenance during a period of years. We are realizing more and more that increased first cost and longer time required for con- struction are usually economical for permanent roads in view I MILITARY ROADS 71 of the lower maintenance charges and the greater satisfaction from the use of the road, the beneficial effects on the growth, the business and social life of the communities affected, etc. But we should also reahze that from a mihtary point of view these considerations have little weight. The army does not expect and does not demand that good roads shall be built under war conditions in the theaters of actual conflict, and moreover it can not brook the delay that their construction would require. Prompt results are demanded, cost is disregarded and make- shifts cheerfully accepted. As military roads are often used For a very short time only and never beyond the end of the war, 'Hie question of maintenance over a period of years does not arise. It will be economical to build an inferior road in the first place and to keep it passable by relatively expensive main- jnance measures during a relatively short period. Earth roads be passable must be kept drained and free from ruts and for mihtary roads ample labor for maintenance will generally be available. The roads should be kept shaped up, ruts filled, ditches kept open. The most efficient method of maintaining earth roads is by dragging, supplemented by hand labor. CHAPTER VI FIELD FORTIFICATION AND SIEGE OPERATIONS Field fortification is the most important and the most dis- tinctively miUtary of the many operations of the field engineer and constitutes an art and a science in itself. The art of fortification includes two branches, known as strategical or dehberate, and tactical or hasty fortification. Strategical fortifications include defensive works executed largely in time of peace for the protection of important harbors, cities, arsenals, etc. Tactical fortifications are those executed to meet the immediate tactical needs of the mobile army in the field, and are hence known also as field fortifications. The line of demarcation between the two classes is not clearly defined. Strategy and tactics are intimately connected and so the works constructed to meet their needs vary from the elaborate coast defense works to the simple trenches of a rear guard fighting a delaying action. The purposes of military operations are to destroy the organized resistance of the enemy or to seize and hold territory which is important to him. For the accomplishment of either purpose aggressive action is required. This aggressive action consists in the concentration of overwhelming force at certain critical points while the enemy is held in check at other points, and it contemplates the probability of similar operations on the part of the enemy. MiUtary operations are accordingly a combina- tion of offensive and defensive action, and success will lie with the combatant who can seize and retain the initiative. Aggressive action, the assumption of the initiative, impUes the power of maneuver in strategical and tactical* combinations. 72 FIELD FORTIFICATION AND SIEGE OPERATIONS 73 Jtrategy maneuvers the troops into the most advantageous posi- ion for battle, but strategical advantages can in general be reaUzed only by wiiming the battle, which is their logical cul- mination. For success in battle the power of tactical maneuver is essential. The immediate purpose of field fortifications is to increase the power of resistance of the troops occupying them by decreasing their exposure to the fire of the enemy and increasing the accuracy and volume of their own fire. They thus serve to hold the enemy in check and limit his power of maneuver. Furthermore, they accompUsh this result with the least number of men, thereby lendering the greatest possible number available for aggressive concentration of superior forces at the critical points. Even in a successful attack the assailant can not advance con- tinuously. Halts will be necessary to permit of the bringing up of supplies and reinforcements, to refresh the troops, to hold the enemy in check, to select new points of attack, to readjust the artillery positions, etc. The assailant at all such halts must cling with the spade to that which he has won with the rifle and bayonet. Troops can not remain stationary upon the field of battle exposed to the fire of the modern rifle, machine gun and artillery. Fortifications therefore, while essentially defensive in their nature, will be extensively employed also in the attack. The neglect to utilize them will involve heavy losses and, if opposed to a skillful adversary, will invite defeat. On the other hand, their excessive and indiscriminate use limits the mobiUty of the troops, tends to destroy the aggressive spirit which is es- sential to success, and surrenders the initiative to the adversary. Field fortifications then are a means to an end. If used in- discriminately, without due regard for the strategical and tactical requirements of the situation, they exercise a most baneful in- fluence. Their correct employment for the achievement of the purpose in view calls for the highest skill of the commander. The technical details of the works themselves are compara- 74 THE ENGINEER IN WAR lively simple and readily comprehended, but their location, arrangement and adaptation to the tactical situation and to the terrain call for a high degree of skill, analogous to that required in road and railroad location. The characteristic features of fortifications in all ages have varied with the nature of the weapons employed and with the particular tactical object in view. Structures which would pro- vide protection against arrows and stones would be quite inade- quate against modern artillery. The hasty outpost trenches of a rear guard in retreat would be quite unsuited to an army en- gaged in a protracted and decisive struggle. In general fortifica- tions are designed to serve two purposes: 1. To facilitate the effective use of the weapons of the defenders; and 2. To restrict the effective use of the weapons of the attackers. All constructions which serve either of these purposes may then be classed as field fortifications and will include the following: (a) Rifle trenches for the firing line and cover trenches for supports. (6) Emplacements for machine guns and artillery. (c) Shelters for protection against fire, particularly shrapnel and high explosive shells, and against weather. (d) Communicating trenches between supports and firing line. (e) Observing stations, dressing stations, kitchens and latrines. if) Obstacles to retard the enemy's advance and hold him under fire, including explosive mines. (g) Demolitions for clearing the field of fire and restricting the tactical maneuvers of the enemy. (h) Measures for concealing all works from the enemy's view. (t) Mining operations or tunneling for subterranean advance against the hostile works. 0") General communications, such as roads, foot paths, light railways, telegraph and telephone lines, signal stations, etc. Most of these works must necessarily be executed by the com- batant troops who are to occupy them, and all line (combatant) officers should be qualified to superintend their construction. The engineers, however, will constantly be called upon for ad- vice and assistance as to location and details, and in the execu- FIELD FORTIFICATION AND SIEGE OPERATIONS 75 Lon of some of the more difficult tasks their special training d equipment will be necessary. Geographical, political and other conditions and strategical lonsiderations will determine the theater of war. The position be occupied and fortified will be fixed by tactical considera- ons. The general line to be occupied will usually be determined om a map, but the actual location of the trenches and accessory orjcs can be satisfactorily made only on the ground. These are certain requirements which experience indicates ihat a defensive position and the works executed thereon should ilfiU. Many of these requirements are at variance with each ither and it will never be practicable to find a single position hich fulfills them all. Skill and experience are necessary to [etermine the requirements which are of paramount importance in any particular case. Often it will be a question simply of making the best of the locality in which the troops find them- selves. Often works hastily constructed on the field of battle are later elaborated and strengthened to meet the developments in the tactical situation until the operations partake very largely of the nature of siege warfare, as is the case today on the western battle front in Europe. The matters to be considered in selecting and organizing a position are: The mission or purpose of the command, their numbers and quaUty; strength, position and probable inten- tions of the enemy; the weapons possessed by both combatants; the nature of the terrain, faciUties for maneuver or retreat; whether delaying or decisive action is contemplated; the time the position must be held; the time available for preparation; etc., etc. The first requirement of a defensive position is that it shall be one which the enemy must attack to accompUsh his mission. If he can attain his purpose without such attack, then the position is useless and the time spent in preparing it wasted. The following are certain additional considerations to be given 76 THE ENGINEER IN WAR such weight as the particular circumstances of the case may require : (a) Is it proper to take up a position, or does the situation call for advance or retreat? (6) Is the position suited to the strength and armament of the force which is to occupy it? (c) Is the position to be held indefinitely? If not, for how long a time? (d) What are the strength and intentions of the enemy? What weapons has he? Is he provided with means for aerial reconnaissance? (c) Are there good positions with clear view and field of fire for both infan- try and artillery? Is there a good field of fire at all ranges? If not, which is more important, a near or distant field of fire? CO What are the facilities for advance or retreat from the position. (g) Are the flanks of the position naturally secure? If not, what expedi- ents may be adopted to secure them? (h) Are the communications within the position good? (i) Is there cover for supports and reserves? (j) Does the terrain present natural features adaptable to defense, or will great labor be required? (k) Is the ground in front such as to facilitate the enemy's attack? Are there natural obstacles to his advance? Are any artificial obstacles re- quired? (0 Is the ground in rear favorable for counter-attack in case the enemy should penetrate the first line of works? (m) Is the position naturally concealed from view, including view by aerial scouts? If not, what artifical means of concealment are possible? (n) How much time is available for the preparation of the position? How much time will each item of the work require, and what is the order of relative importance? How should the labor and tools be distributed to pro- duce the best results? Those and many other important questions must be considered. As has been stated, a single position giving a favorable reply to all these questions will never be found. Any position must })e a compromise between advantages and disadvantages. Success in battle is determined by fire superiority, without which the assailant can not advance and the defender can not hold his ground. Field fortifications increase the fire effect of the troops occupying them and decrease the fire effect of the enemy. They are designed to afford the maximum protection FIELD FORTIFICATION AND SIEGE OPERATIONS- 77 ^■he defender's weapons. H The shelter best fulfilling these requirements is the simple ^■ifle trench from which the soldier may deliver fire in a comfort- H^ble standing position over a low earth parapet or through a RECESSED ^Sk TRAVERSED FIRE TRENCH (no head cover) SECTION Fig. 29. loophole in the parapet. Such rifle trenches are accordingly the principal feature of field fortifications (Figs. 29, 30, 32 and 33). The parapet is made sufficiently thick to resist penetration by rifle bullets or shrapnel, which requires about 3 ft. of ordinary earth. The parapet should be sufficiently high to afford a view of the foreground but in order to be inconspicuous it should be 78 THE ENGINEER IN WAR no higher than necessary for this purpose. Ordinarily its height will be from 9 to 18 in. above the surface of the ground, unless excavation is very difficult in which case a shallower trench and a higher parapet may be used. Such a trench affords no ade- quate protection against direct hits by high-explosive shell, Fia. 30. — Simple rifle trench with sand-bag and hurdle revetment and splinter-proof shelters under parapet. which would destroy the parapet and kill the man behind it. Such shells will also penetrate and demolish any shelter which it is practicable to construct in the field. The only protection against the fire of large cahber guns which troops in field works I FIELD FORTIFICATION AND SIEGE OPERATIONS 79 U 5-G 5 !» S to 0^ O u t < to &^ 6 o . 1S3HQ lV0IHeep Wire SnUnglement ^ — o o— o 9 Shocked Corn| Demolltioa Onltirated Land o e e e e e O e O e O e Orchard o e o e e o •O • • O O Open Woods *0 O *• e Site of Circle Indicate! e o e • • BizeofTreet O o JiL-«-i»-.0. .«.-«- .9. J9. Rough Symbol for Woods Woods with Undergrowth |a.H.| |c.aj School.house.Oonrt-hooae ^1 Masonrjr Building OO Frame Building -X — y — K — x~ Barbed Wire Fence _o — o — o — o— Common Wire Fence t t — I I o ^ o_ Main Road — o — o— o — o— with Plain Wire Fence on both Sidei m"Jl~11Zri Unimproved Road Trail J T T TeleRraph Line Fia. 63. — Conventional signs employed in military sketching. etc. Notes should describe the nature of roads, as — "good macadam, 16 ft.," "good earth, 12 ft., ditches," etc. The span, width of deck, height, material and practicable load of bridges is indicated by notes. Buildings are never drawn to scale, but the size and construction of important buildings may 11x14 1000 Adams Q Scale 3 1 nches =1 M ile 12 3 4 5 6 7 8 9 10 11 12 13 14 15 1600 Yds. I I I I I I I I I I I — ' ' — =« 1 H H 1 Mi. (123) Fig. 64. — Road sketch executed by military methods. Scale 4 Inches -1 Mile. V. I. 15 Feet Fig. 65. — Position sketch executed by military methods. 1500 Yard:! (124) MILITARY RECONNAISSANCE 125 be indicated by a note. Fords are designated by noting width, depth and velocity of stream, nature of approaches and bottom. The names of railroads, gauge, number of tracks, location and capacity of stations, sidings, water tanks, the rolling stock avail- able, etc., are noted, as also the names and distances of adjacent stations in both directions, the vulnerable points of the road, such as large bridges, tunnels, etc. Telegraph and telephone lines are of special importance, the adjacent towns to which they Fig. 66. — Military ski-tclKTs wiih ('(ini])!!!!'!!!. lead should be ascertained by inquiry. Streams which are to be used for water supply may be roughly gauged. Ground suitable for camp sites or defensive positions should be noted, etc. The local resources in the way of crops, animals, foodstuffs, tools, machinery, etc., should be ascertained approximately. Towns are described by giving their populations, nature of in- dustries, stock and output of mills and factories, important build- ings, railroads, telegraph and telephone communications, etc. There is hardly a local feature which may not be of importance 126 THE ENGINEER IN WAR from a military point of view. The reconnaissance will generally be for the purpose of investigating certain particular conditions, but even under such instructions very important matters out- side of the instructions should be reported. The officer charged with such duty must have his powers of observation and acquisitiveness developed to a high degree. By the methods herein outlined a competent sketcher may map ten or more miles of road per day, sketching in also the topography on each side which is visible from the road. In sketching an area he may cover from J^ to 2 sq. miles in a day, depending upon his skill and the nature of the terrain (Figs. 64 and 65). Where an extensive area is to be surveyed the work is divided into a number of small areas, with natural or artificial hnes of division, which are mapped simultaneously (Fig. 66). A number of these area^ will be in charge of a principal sketcher whose duty is to distribute his subordinates, fixing the hmits assigned to each. He makes certain that each individual sketcher connects with his neighbor on either flank by having one or more points in common, without overlapping or dupHcat- ing work further than is necessary to join the two sketches in one. He carries an aneroid barometer with which he gives each sketcher the elevation of his starting point. He may be ac- companied by an assistant who measures the distances and sketches the important features along the base hne from which the area sketchers start. This is used later to combine and co- ordinate the individual sketches. These are turned in simul- taneously and are pieced together and retraced or otherwise prepared for reproduction. As the sketches are usually made on translucent vellum they maj^ be printed directly. Mapping operations on a large scale will ordinarily involve the correction, amplification, compilation and reproduction of maps, and this duty will fall to the Engineer Department. So far as possible it should be done in the office, away from the haste and confusion of the field. But much of this work must necessarily be done in the field, especially reproduction. Actinic MILITARY RECONNAISSANCE 127 printing processes are often too slow for satisfactory reproduction in the field. If blueprinting is employed the rate of reproduction may be greatly increased by using brown print (maduro) nega- tives, from each of which blueprints may be produced as rapidly as from the original tracing. The hectograph is also useful for reproducing small sketches. It is light, portable and simple in operation, more rapid than blueprinting, and has a further advantage in that maps in several colors may be produced in one operation. The best field method now generally employed is lithography, or rather zincography, since the excessive weight of litho stones renders them inconvenient for rapid transporta- tion. The engineer troops are accordingly supplied with an efficient and portable outfit for map compilation and reproduc- tion, including drafting, photographic, actinic printing and hthographic (zinc) apparatus. This is one of the most important items of their equipment. Fig. 67 indicates the manner in which a piece of ground is contoured l)y the methods of rapid military sketching herein- before outlined. For the sake of simplicity such features as buildings, fences, trees, etc., are omitted, although these would, of course, appear on a complete sketch and, moreover, are important as references and control in plotting the critical points of the terrain. In Fig. A the sketcher has determined and placed upon his sheet the drainage lines of the area with a number of elevations on each. He has also determined and plotted the horizontal positions and elevations of the tops of hills and the crests of ridges and of the points where there is a marked change in slope, as at 830 in the northeast portion of the area. This data constitutes the control or skeleton of his sketch, and if the work has been carefully done and no critical points omitted it will be possible to make a fairly accurate contoured map of the area without any additional information and without again seeing the ground. It was observed that the slopes of the stream beds were fairly uniform, that is to say, in this case there were no waterfalls. 128 THE ENGINEER IN WAR y 1 1 861 -860 790/ 873 \ \ 872« 870 I \ 830 ^, \ \ \ \ 1 J* 8i0 ■ ■ ^ 8S0 /I 1 / 1 1 1 1 I 1 870 I >880 / 1 1 1 / / / / / / / 88S / / / / / / * 92 8C5 ^^845 Arrow bead* show direction of water flow. i k -867 -8S0 790/ r t J / V 873 T ^ ^'«. '/ -^ \ 872" 870 i y ■*830 \ V ^^ ^ — ^ t -< -»86o ;i lEf"""""""* y ■^ ♦«,« / 4 / \ 850 / / •910 1 1 / f T / 1 1 * )^ / / «88S i860 1^^ y / ♦■ -892 -;« 5 Arrowheads (except those appearing also on il) are points where contours cross streams or dry runs. Fig. 67a. — The evolution of a military contoured sketch. MILITARY RECONNAISSANCE 129 Fig. 676. — The evolution of a military contoured sketch. 130 THE ENGINEER IN WAR In Fig. B the sketcher has placed the contour points on the drainage lines. These may be spaced uniformly or the stream beds may be made slightly steeper at their upper ends, as will usually be the case. The sketcher also places the contour points on the axis of the ridge in the eastern part of the area. As the plotted elevations indicate a change of slope from quite steep at the bottom to a gentle slope higher up, the coiitour points are spaced accordingly. He now sketches in the contours, on the controlling points thus determined, Fig. C. By similar procedure the balance of the area is filled in and Fig. D presents the complete sketch. In practice the contours would usually be sketched on the ground or "in sight of the facts." Thus, in placing the contours shown in Fig. C, the sketcher might stand at 860 where he could see the drainage lines on all sides. By thus viewing the terrain the sketcher would note the small details of the ground forms and portray them on his sketch. Thus, the small fold or drainage line beginning at 850 near the center of the area could be sketched in quite accurately by eye, even if it had not previously been included in the skeleton, as shown in Fig. A. For purposes of instruction, however, the sketchers are required to prepare Fig. A in the field and then to fill in the contours with- out viewing the terrain. This gives them excellent instruction in portraying ground forms and by comparing their sketches thus prepared with a more accurate map of the same area thoy will note the faults they have committed, and especially the critical points which they have failed to perceive and locate in the field. MAP READING While not every officer and non-commissioned officer will be called upon to make maps and sketches, all, from the highest to the lowest, will frequently have to read and interpret them. An officer who is not an adept in map reading will be at a great dis- advantage in the exercise of independent command. The map MILITARY RECONNAISSANCE 131 should convey to his mind a fairly accurate picture of the actual ground, and he should be able to rapidly and accurately obtain any information which the map can furnish. Such facility is acquired only by long practice. To locate one's position on a map, to orient it, to determine the difference of elevation or the distance between two points are apparently simple matters, but if it is a question of moving troops there are many other con- siderations. What are the widths, character and condition of the roads? What grades will be encountered? At what aver- age speed can a wagon train move? Is the road open or shady? Can it be easily observed from adjacent heights, or possibly fired upon? What towns lie upon it? Is there a telegraph line alongside? Are there bridges over the streams? If so, are they in good condition and amply strong to carry the loads accompanying the army? If not, how long will it take the en- gineers to fix them? Are there fords nearby? What are the depths of water? What effect do floods have? Is a certain locality suitable as a camp site for a certain body of troops? How about the water supply? Is there shade? Is the drain- age satisfactory? Is fuel available? How should the various organizations be disposed? Is the locality defensible? Where should the outpost line be placed and how many men will be required to cover it? If a defensive position is to be taken to cover some important point or some movement of troops, where is the best general line for occupation? Can the enemy avoid it or must he attack? Is there natural cover available? How about the roads and other communications? Are there good observing stations and sites for the artillery? Is the field of fire satisfactory? What natural obstacles exist? How about the facilities for retreat or withdrawal? Are the flanks secure? What materials for construction will probably be available? Can civilian labor be secured — if so — to what extent? These and many similar questions must be tentatively answered from maps, sketches and reports of reconnoitering parties, but it is to be remarked that the final dispositions will almost invariably 132 THE ENGINEER IN WAR be made upon the ground itself, for the best map can not answer all questions that arise. One interesting problem that is often encountered in military operations is that of visibility, a question as to whether a certain point or area is visible from a certain other point. Such a problem can seldom be solved with great precision on a map, but an approximate solution will often be required. Thus, in the case of a movement of troops, is the road along which they will march visible from certain commanding points in the vicinity? If so, what parts of the road? If it is desired to conceal the move- ment from the enemy, as will usually be the case, such observa- tion points should be determined and either avoided or occupied in advance in order to prevent the enemy from doing so. Artil- lery requires observing stations from which its field of fire can be observed. It is necessary to select these positions, to ascer- tain the areas visible from each, to determine whether obser- vation towers are needed and, if so, how high they must be, etc. The solution of visibility problems involves the construction of profiles (Fig. 68). As this is a tedious process short cuts are usually employed. One who is proficient in map reading can solve the less critical problems at a glance. If there be inter- vening ridges it is often necessary to fix the height of the line of sight at such ridges. Visibility problems may be solved by proportion and by the use of the slide rule. The following rouph method will also be found useful in many cases. A red rubber band is graduated in tens and hundreds on any scale. The tens are numbered, the hundreds are not. Now suppose, for example, that the elevation of the point of sight is 410 and that of the point to be observed 290. Stretch the rubber band so that the first 90 falls on the point to be observed and the second 10 following on the point of sight. Then the elevation of the line of sight where it crosses the intervening ridge is read on the band. If this is greater than the ground elevation as shown by the con- tours, the two points are mutually visible, each from each. Of course if there are trees growing on the ridge it is necessary to MILITARY RECONNAISSANCE 133 Fig. 68. — The construction of a profile. 134 THE ENGINEER IN WAR MILITARY RECONNAISSANCE 135 make allowance for these. To determine what area is visible from a given point, draw a number of radial lines from the point. An inspection of the map will usually determine the intervening ridges or hills which will limit the visibility. Mark the critical points on each line of sight. Now stretch the rubber band so that the proper elevations fall on the point of sight and an intercepting point, look along the band and find the point where the graduation on the band coincides with the elevation on the map. This will be the point where the line of sight strikes the ground. Look back along the band and make certain that at all points between the point of sight and the assumed intercept- ing point the line of sight is above the ground. By joining the points thus determined with broken lines the approximate boundaries of the visible and invisible areas are determined. The invisible areas should be shaded. Photography is of little practical use for map making for military purposes except in the case of photographs taken from a balloon or aeroplane at a considerable height, which are in effect a form of map. But photographs are a valuable accessory to maps in giving a clearer appreciation of the terrain as it appears to the eye. They are of great value for showing the construction and condition of bridges, wharves, buildings, etc. Landscape sketches are usually of more value than photographs, inasmuch as they give special prominence to the important features of the terrain, omitting the mass of details which obscure the critical points (Fig. 69). Acknowledgment. — Most of the figures accompanying this chapter are taken fro^l ''MiUtary Topography," by Major C. 0. Sherrill, Corps of Engineers, U. S. Army, the leading American work on this subject. CHAPTER IX MILITARY SANITATION A sound physique and rugged health are essential prerequisites of military training and military service. The fighting effi- ciency of the troops is directly dependent upon the maintenance of their health, which is accordingly of prime importance, not only from a humanitarian but more particularly from a purely tactical point of view. The history of the past wars shows that the losses of armies due to sickness have far exceeded those of battle. Camp epidemics have decided the issue of war, the fate of nations and the progress of civihzation. Sanitation may be regarded then as coordinate with strategy and tactics in the conduct of war. Sanitation is the particular field of the medical department but its success in this field is contingent upon the obedience and intelligent cooperation of all officers and men of all arms. The sanitary fimctions of the engineers are distinctly subordinate 'to those of the medical department, arid consist in executing the more important engineering operations demanded by sani- tary requirements. These operations are similar to those of the civil sanitary engineer, but hke other works of miUtary engi- neering, are generally less formal and more in the nature of make- shifts. Such operations will be required wherever troops are assembled, in concentration and training camps, in the trenches and on the march. * On the battlefield, in the presence of the enemy, efficient sani- tation will be difficult enough, and remarkable are the make- shifts by wliich it is effected. But it is not here alone that sick- ness and pestilence will exercise their baneful influence. The 136 MILITARY SANITATION 137 volunteer army must be mobilized and receive its final training at the great camps that will be estabUshed for that purpose in various parts of the country. The general location of these camps will be determined by strategical considerations, but in the selection of the actual sites tactical requirements will have no weight and the camps should be located with a view to efficient sanitation. This has not always been done. The raw levies, uninstructed in outdoor personal hygiene and sanitation, have often been assembled in great numbers in unsanitary localities and sickness and camp epidemics have been the logical results. The sites for these concentration camps should be carefully selected in time of peace, taking into consideration the strategical and sanitary requirements. While it will not always be prac- ticable to reserve large areas exclusively for this purpose, and to provide in advance the communications, drainage, water sup- ply, etc,, yet plans should be made by which the sites can be rendered promptly available when needed. The necessary sanitary measures should then be planned in time of peace and carried out before the arrival of the troops. Subsequent to the arrival of the troops their instruction in personal hygiene and the rudiments of miUtary sanitation will be not less important than their instruction along other Hues. The most important engineering operations in connection with sanitation are water supply, drainage and sewage disposal. Other vital engineering requirements of the sanitarian, such as transportation, the construction of hospitals, depots, etc., are neither distinctly military nor distinctly sanitary. If the mili- tary engineer is to render inteUigent aid to the sanitarian he must be well versed in the principles and methods of civil sani- tation and capable of adapting these to mihtary needs, often under trying circumstances. At any site which troops are to occupy for a considerable time efficient sanitary measures will be necessary for the preservation of their health and morale. This will apply as well tp defensive positions on the battlefield as to camps at some distance from the 138 THE ENGINEER IN WAR theater of actual conflict. A site naturally healthy should be selected for occupation whenever conditions permit. The sit« should be well drained and open to sun and air. High ground with a sandy or gravelly soil or good firm turf is to be preferred. In warm weather an open wood affords protection from, the heat while permitting the circulation of air. In cold weather a southern exposure with a hill or wood to give protection from the prevailing wind is desirable. Strategical and tactical con- siderations are usually paramount, but the most healthful site which these considerations permit should always be selected. In the selection of the site the engineer will of course be called in consultation. Above all, an ample supply of good water must be available, since impure water is the most effective means of transmission of some of the most usual and dangerous of camp epidemics, including typhoid fever, dysentery and cholera. Drainage should be efficient, and measures adopted for dis- posing of sewage and kitchen waste. When flies and mosquitoes are plentiful special measures may be taken to abate such nuisance and danger as their presence entails. The most important duty of the mihtary sanitarian is not to cure sickness but to prevent it. For the permanent concentration camps one of the approved civil methods of water supply ma}- be adopted. If the camp 1)0 near a large city having a good water supply the latter may he used, at least for drinking and cooking purposes, the use of water by the civil population being curtailed if necessary. The amount of water to be supplied is indicated by the experience of civil communities. Many civil uses of water may, however, be greatly limited or entirely dispensed with. These may include such items as flushing the streets, elaborate water-borne sewage sj'stems, etc. As military discipline permits thorough regulation of the use of water, much of the waste characteristic of civil communities, especially where the supply is unmeteretl, may be ehminated. The camp may also to some extent be located and arranged with a view to facihtating the water supply. It will usually be impracticable to adopt the modern MILITARY SANITATION 139 method of slow sand filtration on a large scale, unless such has been installed during peace, since the construction of the filters requires considerable time. For similar reasons a gravity supply is to be preferred to one which requires pumping. Never- theless, pumping must often be resorted to, and it is to be re- marked that the high pressure required for distribution over a wide area and for fire protection, etc., will seldom be necessary. A natural site where a storage reservoir of adequate capacity may be created by a hastily constructed earth dam should be sought. If its elevation is such that pumping may be avoided so much the better. A camp site near a large river or a lake is often advantageous, but in such case an intake and pumping plant will usually be necessary, and possibly also settling basins and tanks or distributing reservoirs. Smaller streams may be dammed, always upstream from the camp. The storage reservoirs may serve also as settling basins for plain sedimenta- tion and chemical coagulants and mechanical filters may be used. Deep-driven wells are often a convenient and satisfactory source of supply. Distillation furnishes the purest possible water, but is usually impracticable on a large scale. It may often be advantageously emploj-ed to furnish drinking water for small commands. The most common method of providing potable water for military uses is by boiling, preceded by sedimentation where necessary. Boiling for five minutes will destroy the germs of typhoid or enteric fever and of cholera. Boiling for fifteen minutes will destroy all pathogenic germs. Stationary and portable boilers are employed. The method has the disadvantage that it requires fuel and is slow. For these reasons many experiments have been made to devise a form of mechanical filter suitable for military uses. No en- tirely satisfactory device has ever been produced. In their operations on the western battle front in Europe the French, after having experimented with many types of filters, all of which were unsatisfactory, have adopted purification by the use of sodium hypochlorite. The purified water is distributed to the 140 THE ENGINEER IN WAR troops in wheeled tanks, and this method is said to be satis- factory. While it would often be practicable to pipe the supply of drinking water, the waste would probably be much greater than where it is delivered in tanks. Water for bathing purposes, as it need not be purified and often not even clarified, may be advantageously distributed by piping. Wooden stave tanks and gas engine pumping plants, as they are easily transported and erected, are well adapted to mihtary uses. On the march and in temporary camps some dry sewage method must usually be adopted. The simplest scheme of this kind is a pit or trench, preferably one enclosed or sheltered by a screen and, if necessary, provided with a cover such as a tent or a thatch on poles. Earth and lime are employed for covering and deodorizing and if flies are abundant the pit may be screened. Such pits with their shelters are known as latrines. When a camp is occupied for any considerable length of time the latrine method is objectionable. A more sanitary arrangement is incineration. There are many forms of incinerators, one especially adapted to mihtary uses being a furnace and latrine combined, the whole mounted on wheels for transport. On the battlefield latrines will be employed in the trenches, but if these are to be occupied for some time the pail system should be employed, the contents of the pails being removed for incinera- tion back of the Une. Another expedient would be water closets and cesspools, but as the latter are now almost universally condemned septic tanks will be preferable and often not much more difficult to provide. Incineration is the most sanitary method of disposing of kitchen waste. In concentration camps more elaborate measures are prac- ticable which, as in the case of water supply, may sometimes bo carried out, or at least planned in advance of the outbreak of hostihties. These may include the most approved modern methods of sewage disposal. Military sanitation bears the same relation to civil sanita- tion that other Unes of mihtary engineering bear to the corre- MILITARY SANITATION 141 spending lines of civil work. That is to say, it is' a more or less hasty and makeshift adaptation of civil methods to miUtary needs. To achieve success under the difficulties which will be encountered in war time the mihtary engineer should be ac- quainted with the theory and practice of civil sanitary engineer- ing and capable of adapting them to military needs. CHAPTER X THE MOBILIZATION OF MATERIAL RESOURCES The modern theory of war, as we have seen, contemplates in it« highest development not only the universal training of the personnel, but the complete mobilization of the material re- sources of the nation. An army numbering millions requires in its operations vast quantities of supplies of all kinds. Unless these supplies are forthcoming as needed the nation's defenders, however intelligently organized and splendidly trained, will be unable to successfully oppose the fully equipped troops they will be called upon to meet in the event of war with a foreign power. Such has been the situation of more than one of the nations in the present war. The supplies necessary are not limited to weapons, ammuni- tion, foodstuffs and clothing, but include the great bulk of the products of our farms, mines, forests and factories. There is also demanded the service of our transportation systems by land and water. Our material resources exceed those of any other nation and are ample for the prosecution of a great and pro- tracted conflict. They are at present, however, very poorly organized from the point of view of military necessity. This is plainly indicated by the lack of system, the delays and ex- travagance which are attending the furnishing of munitions of war to the European nations. Europe has paid for our inefficiency, but the experience acquired by our manufacturers and their agents will be of undoubted benefit to our own de- fensive polic}'. In mobilizing our material resources it is necessary first to ascertain our probable needs in the event of war. We should then investigate and make record of the sources from which 142 THE MOBILIZATION OF MATERIAL RESOURCES 143 these needs may be supplied, and finally execute all possible preliminary measures necessary to stimulate production. The problem is a vast one, second in importance only to the training of personnel. We can here consider but a few of its most saHent features under the three general heads, to wit : (a) Probable needs. (6) Investigation of sources of supply. (c) Stimulative measures. The material required for the conduct of war may be classified under two heads: 1. Commercial materials, tools or appliances, that is to say, those which are manufactured and used in large quantities in times of peace: and 2. Materials or equipment which are peculiar to warfare and not ordi- narily manufactured at all, or to a limited extent only, for commercial pur- posesj'and which can not, therefore, be readily obtained on short notice. The line of demarcation between the two classes is not defi- nitely fixed. Examples of the first class would be axes, barbed wire, automobiles, shoes, anesthetics, dynamite; of the second class, military rifles, portable intrenching tools, haversacks, ponton boats. In the event of war the regular and volunteer forces would be called at once to the colors and sent to the front as rapidly as they could be equipped and trained (in the case of volunteers). In order that these troops may be promptly equipped for duty it will be necessary to keep on hand in time of peace a reserve of material, especially of the second class. This reserve should obviously be no larger than necessary — it will be great enough in any case. Its storage and care will be expensive, some of it will become obsolete from time to time, and some will deteriorate and become useless in storage — all of it will represent an invest- ment paying no direct return except in case of war. The amount of each item of this reserve will depend, first, on the requirements of war and, second, on the predetermined rate of production and delivery subsequent to the. outbreak of war. The plans of the general staff will contemplate certain con- 144 TffE ENGINEER IN WAR tingencies, and the enrollment, training and equipment of successive levnes of men to meet these contingencies. Measures for the mobilization of the material resources should be based upon the greatest probable requirements, but should look further to the possible ultimate utilization of all our resources. A consideration of these probable requirements will indicate what will be needed at the outbreak of war and the rate of production that must be maintained thereafter, if mihtary operations are not to be delayed or hampered by lack of equipment and supplies. Supphes for military purposes can be more readily, quickly and cheaply obtained the more nearly they conform to commercial tjrpes and standards. Hence, as far as practicable, they should be identical with or similar to the products of peace time. Many of them, of course, must be specially adapted to military needs. Having tabulated these materials the next step is an investi- gation of the sources of supply. Or, to avoid delay, the t^^o investigations may be prosecuted simultaneously. All existing supplies which can be commandeered in case of need without undue hardship to the civil population, such as automobiles and animals, should be located and recorded. Every manufactory in the land, both large and small, should then be investigated to ascertain what material it could produce for military purpos(\s under war conditions. The somewhat modified requirements of the civil population during the war must, of course, also ho considered and provided for. This material would not in all cases be limited to the regular output of the factory. We should consider not only what the factory does ordinarily produce Init what it might reasonably be counted upon to produce with due regard to efficiency and economy. It will be necessary also to ascertain the time that would be required to equip the plant and train the operatives to produce a different line of products. The average American industrial plant can not change in a day, a week, or even a month from its regular output to a now line, unless careful and inteUigent . preparation be made in advance. Without such preparedness it might be a year before THE MOBILIZATION OF MATERIAL RESOURCES 145 the plant would be operating in an efficient and economical manner in the production of munitions, and then perhaps it might be too late. This consideration is regarded as of vital importance to the national defense. One of the most important features, therefore, of the mobiliza- tion of resources is a study of the stimulative measures that may be planned in advance to increase the rate of output. There will be many such measures and they must be carefully thought out. The writer undertakes to direct attention to but a few of these. To begin, as has been pointed out, military supplies should, as far as practicable, conform to established standards. The plans and specifications of these materials should be sub- mitted to the scrutiny of manufacturers. They will thus be able to point out many modifications which will cheapen and speed up the output without seriously affecting the mihtary value of the product. So far as possible, the manufacturers should specialize along their regular lines. The revised plans and specifications should be placed with the manufacturers for study as to measures necessary for rapid production. Experimental samples of each class of supplies should be pro- duced. This would indicate the methods to be followed in manu- facture and the tools and machines that would be required in addition to the regular equipment of the factory. These models and samples, with detailed instructions as to methods of fabrica- tion, should then be placed with important factories or groups of factories. All special tools, machines, gauges and patterns that would be needed should be devised. An ample reserve of these accessories should be kept on hand by the government and also placed in the factories themselves, and necessary ar- rangements made to augment the supply, to the end that at the outbreak of war all factories from which material would be demanded might be properly and quickly equipped to produce this material. The assistance of the manufacturers themselves will be most helpful. Organizations of manufacturers to assist in the investi- 10 146 THE ENGINEER IN WAR gation and lining out of plans have been suggested. A thought- ful and interesting study along these lines was presented in a pamphlet recently published by Mr. Martin J. Gillen, President of the Mitchell Wagon Co. It should be remembered that many of our most important manufactories lie close to the Atlantic Seaboard and might be subject to capture in case of invasion. Due allowance should be made for this fact, unfortunate from a mihtary point of view, and corresponding rehance placed upon manufactories farther in the interior of the country which might better hope to enjoy immunity from hostile interference. Having determined the probable rate of output, a reasonable allowance should be made for a possible increase in demand and for the possible effect of the emergencies of war time on the predetermined rate of output of industrial plants. The mobilization of our industrial personnel would be a necessarj' and important feature of this general scheme. During the war, the demands of the civil population would be greatly modified and production along certain Hnes would be much diminished. Certain factories, very many in the aggregate, could be devoted exclusively to the production of munitions of war, and should make preparation in advance, so far as prac- ticable, to take up this work. A readjustment of the industrial personnel would be required to meet war conditions. Many workmen would be thrown out of employment by diminished demand for certain commodities and would be available for transfer elsewhere. Many also would be drawn for service in the volunteer army. There are certain industrial operations in which women are nearly if not quite as efficient as men. The field of their usefulness should be investigated with a view to re- leasing many men from industry to serve with the army. In this manner the women could perform a duty quite as necessary and important as actual service in the field. The question of resources is not limited to the supply of muni- tions of war. The government must look also to the needs of THE MOBILIZATION OF MATERIAL RESOURCES 147 the civil population during war time. For a nation which has not been self-sustaining during peace (and none of the civiHzed nations is entirely so) and finds its outside sources of supply cut off by war, the problem may be a serious one. The United States can be entirely self-supporting. We can produce within our own borders all of the necessaries of life and all the munitions of war, and this is an important element in our potential strength. Nevertheless the transition from the conditions of peace to those of war will be a tremendous wrench and the suffering amongst certain elements of our population, even in localities not directly touched by war, will be great. Many of the industries which supply the things that make life worth living without being abso- lutely necessary to its mere maintenance, or those producing for export or relying on imports would be paralyzed by the cessation of demand for their products or the impossibility of marketing their wares or obtaining their materials. Their employees would be thrown out of work and would have to be otherwise provided for. Thus the demand for amusements, such as the theater and music, would be greatly diminished, as also the de- mand for luxuries in food and dress; financial operations, trading in stocks and bonds and real estate, building operations, the promotion of new industries would all be greatly curtailed; im- port^ and exports might be absolutely shut off — our foreign purchasing and selling markets closed to us at the very time when the home markets were dull. While many of the activities would eventually revive, the hardships for a time would be very great. Governmental aid and governmental foresight will be necessary to maintain confidence, prevent the sudden changes in condi- t ions, allay panics, and afford succor; all with a view to ameliorat- ing as much as possible the hardships which war inevitably entails. As the government depends on the people, so also would the people depend on the government. To conduct the investigations and institute the measures herein outhned, the assistance of the engineering profession will be absolutely necessary. Steps have already been taken 148 THE ENGINEER IN WAR by the President of the United States to enlist the aid of the great engineering societies in carrying out these investigations. As the inquiry proceeds the stimulative measures which may be advantageously employed should become apparent. Many manufacturers and engineers with manufacturing ex- perience may render valuable service as consulting experts to the plants engaged in the production of war munitions, and the engineering profession should make known to the government the identity of the men who are qualified to render this im- portant service. In the event of war there would be organized in the War Department a bureau to supervise and stimulate the production and arrange for the transportation and delivery of supplies. Many engineers would be employed in such a bureau. Manufacturers* associations and labor unions must play their part as a patriotic duty. It is very desirable that we be spared the humiliating and distressing spectacle of frequent strikes over questions of wages and hours of labor at a time when the fate of the nation is in the balance. In the event of war the demands on our transportation systems will be very heavy and it is necessary that we take careful ac- count of our stock. Many railroads and steamship lines would be taken in complete charge by the federal authorities and all would be subject to a degree of federal military control. This control must be sufficient to meet miUtary needs but can best be exercised through the medium of our big, experienced rail- road men. If any attempt is made to replace entirely the expert personnel of the railroads with army officers having little or no experience in railroad administration and operation, a paralysis of our transportation systems would be the logical result. This mobilization of our resources in material and transporta- tion must probably of necessity be based on the voluntary service which is contemplated by our military policy. Nevertheless, as the government has the power to institute compulsory service in case of need, so also has it the power to commandeer the THE MOBILIZATION OF MATERIAL RESOURCES 149 output of our factories, and even to regulate the sale of the necessaries of life to the civil population. One question not to be overlooked is that of the prices to be paid for war material. The prices charged the European nations by American manufacturers have, in general, been excessively- high, due in large measure to our lack of knowledge of require- ments and our inefficiency in a new field of industry. It is be- lieved that our manufacturers generally would have no wish to derive excessive and unreasonable profits from the agony of the nation. And on the other hand, they should not be required to bear more than their share of the burden by being paid less than the cost of production. It is in the interest of both parties that fair and reasonable prices should be fixed upon in conference and revised from time to time to meet changed conditions. The prices should not be perfectly rigid but capable of adjustment, perhaps on a "cost plus fair profit '* basis, or on some other basis which would avoid the necessity for audit of the manu- facturers' accounts. The mobilization plans and data should be kept up to date. The opening of new factories, the enlargement or discontinuance of any already Usted should be noted, and allowance made for the effect of changes in • industrial conditions, etc. Plans and specifications should be modified or improved where necessary to meet changed conditions or keep pace with industrial progress and invention. Schedules of prices as agreed upon or fixed by the government after investigation should be prepared, and the quota of each factory determined and assigned. With this information as to our resources in hand, and with all practicable stimulative measures in effect the government will be able to avoid much of the delay and confusion which have in the past so frequently marred the success of mihtary operations. It will be possible to intelligently determine the nature and amount of the reserve supplies and equipment which should be kept on hand, and the number, capacity and location of the government munition plants which should be maintained in 150 THE ENGINEER IN WAR time of peace. In common with the training of our personnel this mobiUzation of our resources in advance of the outbreak of war will cost money — not a small sum. But in the event of war the returns on the investment would be large. And as with most things that are worth having this security is worth paying for. We must divorce ourselves completely from the false hope that we can obtain something for nothing — a hope be it said, long dear to the hearts of the American people, and which has too frequently in the past been characteristic of our military pohcy. In conducting the investigations as to resources and in super- vising and stimulating the output, the engineering profession can render a most valuable patriotic service as intermediaries between the War and Navy Departments and the producers. The country will be greatly dependent upon the profession in this matter, since there is no other class of men, civil or military, so well qualified to perform this important duty. Because of our vast resources we have a tendency to regard the question of supplying the sinews of war rather lightly. We are aware that the resources exist and we comfort ourselves with the hope that the supply of suitable manufactured material is a matter that will take care of itself, although we should know that such is not the fact and that intelligent preparation in advance is just as necessary as in the matter of personnel. The nation whose resources in material are limited must look with especial care to the conservation and mobihzation of these resources. Because our resources are not limited we give ourselves little concern in the matter. But are we not short-sighted in this respect? Are we not, to use a slang expression, ''overlooking our best bet?" There has been hardly a miUtary campaign in the history of the world in which the belligerents have not been more or less hampered by a shortage of ammunition and supplies, either immediate or prospective. Thus in the present war, Russia on several occasions has been unable, in spite of ample personnel, to successfully oppose the German troops because of THE MOBILIZATION OF MATERIAL RESOURCES 151 a shortage of material, and she has been compelled to forego success which might have been gained, and has been forced to sacrifice many valuable lives which might otherwise have been spared. Several of the great ''drives" indulged in by various belligerents have fallen far short of a full measure of success partly because an inexhaustible supply of ammunition was not available. Now it is true that we possess accumulated wealth and material resources exceeding those of any other nation, and our manufac- turing equipment and methods are the greatest and most efficient in the world. If our advantages in these respects could be brought to bear we could furnish the materials of warfare at a rate with which no other nation could keep pace. Should we not take advantage of these circumstances to insure our success in case of war, and to purchase that success with the least expendi- ture of our most valuable possession — the lives of the nation's defenders? In other words, if a fighting man knows that he has an inherent advantage over all possible opponents in some one particular which they can not evade, is he not wise if he develops this advantage to the utmost and then conducts the combat in such a manner as to make his advantage the determining factor in the result? Superior material alone can not win battles nor compensate the lack of trained personnel. But its possession constitutes an advantage which, other things being equal, will determine the issue of the conflict. Sir John French, late commander-in-chief of the British forces "The power of defense conferred by modern weapons is the main cause for the long duration of the battles of the present day, and it is this fact which mainly accounts for such loss and waste of life. Both one and the other can, however, be shortened and lessened if attacks can be supported by a most efficient and powerful force of artillery available; but an almost unlimited supply of ammunition is necessary, and a most liberal discretionary power as to its use must be given to artillery com- manders. I am confident this is the only means by which great results can be obtained with a minmuim of loss." CHAPTER XI HOW MAY THE ENGINEERS AND CONTRACTORS OF AMERICA PREPARE TO MEET THE MILITARY OBLIGATIONS OF CITIZENSHIP? We have now considered our present military policy and have seen how this policy precludes that thorough preparation for war which is possible only by means of large standing armies and trained reserves. It will be apparent to the reader that the national defense reUes at present chiefly upon the patriotic willingness of our citizens to partially prepare themselves during peace for volunteer duty in war. We have briefly reviewed some of the principal operations of military field engineering and have indicated the essential differences between miUtary and civil practice. In what respects are our civil engineers and contractors quali- fied to meet the military obligations of citizenship, and what may they do under present conditions to increase their efficiency? There is no class of our citizens more intelligent or more patriotic than the engineering profession. But patriotism which finds its expression in tear-dimmed eyes and choked throats is of no practical value to the national defense. The highest form of patriotism, the only useful form, is that which recognizes the obligation of citizenship and voluntarily prepares to meet it. The engineer oflicer, as we have seen, must be both a soldier and an engineer. If it be necessary for the volunteer candidate to acquire both these qualifications, a considerable period will be required for his proper training and he will not be ready to take the field at the same time as the volunteers of other arms. Our civil engineers and contractors, possessing in advance the technical training in construction, constitute the best material 152 MILITARY OBLIGATIONS OF CITIZENSHIP 153 for the supply of engineer officers. Contractors may be of very great help. The hustling American contractor possesses most of the qualifications so necessary in the successful military engineer. He is often in these days a man with technical training, he is always used to outdoor work, he knows how to handle men and is familiar with construction plant, he has initiative and resource (otherwise he would seek a different profession), and he appreciates the importance of speed in construction work. The eye of the military appraiser turns appreciatively upon the contractor, who possesses so many of the qualifications he seeks. Contractors* foremen, being used to handUng men and outdoor construction, will constitute excellent material for non-com- missioned officers of engineers — the pioneers of the mobile army. For the rank and file of the volunteer engineer battalion we may find ample material in our great industrial organization. Of all these candidates there is none more valuable than the man who has had experience as a laborer on general contract work. He is usually handy, used to outdoor work and exposure and, to a con- siderable degree, is disciplined in a miUtary sense. The con- tractor, his foreman and his gang are of great value as a military asset. Men with some outdoor experience will ordinarily be preferable to those whose careers have been limited to the office. But however thorough his technical training, however ex- tensive his experience, and however great his natural adaptability and resource, the civihan engineer has very much indeed to learn before he will be qualified to perform his military duties. He must learn his duties as a soldier, acquire a practical knowledge of tactics, and adapt his civil engineering knowledge to military requirements. In most instances he must divest himself of certain preconceived ideas and methods. In view of the very short time that will be allowed for intensive training after the outbreak of war before the volunteer army will be called upon to take its place in the line of battle, it is absolutely essential that some portion of this necessary training be obtained in time 154 THE ENGINEER IN WAR of peace, especially in the case of engineers. How may this be accomplished? Assuming the patriotic willingness of the en- gineering profession to meet the obligations of citizenship, how may they be afforded the opportunity to acquire training? The first step manifestly is to interest the profession in this important matter of national defense. They must be brought to a realization of what our military policy is, the extent of its reliance upon voluntary service, and how important is the part of the engineer in any scheme of defense that is likely to be adopted by the American people. It is not only necessary to arouse this interest on the part of the profession but to maintain it, which is equally important and far more difficult. With a great war now going on in Europe there is little difficulty in interesting the people of this country in miUtary affairs. But experience shows that our martial ardor cools very rapidly as the scenes of actual warfare recede into the past. It will be necessary to devise some system by which those men who are willing to undergo training can be instructed in the duties of military engineering. It is too much to expect of the average civilian engineer that he would pursue a lonely course of study on a subject outside of his regular practice, one, moreover, which holds out no promise of financial return. The driving force or incentive to the pursuit of such study would be lacking, and the men would be glad to have some form of compulsion or obligation applied. Moreover, such study would produce little result except under the guidance of professional engineer officers. Also, the study should be supplemented by practical training in the field. To produce results then, it is apparent that this instruction must be subsidized and directed by the War Depart- ment. The engineering societies might advantageously act as intermediaries between the government and the individuals, chiefly in the important matter of attendance, though it is not intended to suggest that the instruction be limited to members of such societies. Several schemes for such instruction suggest themselves. A MILITARY OBLIGATIONS OF CITIZENSHIP 155 number of colleges and universities have, at present, courses of military instruction, and it is possible that the number of such will be increased in the not distant future. At engineering colleges this military instruction might readily be extended to include a course in practical miUtary engineering, with class-room work, lectures and field instruction. The course would cover the more important duties that have been heretofore outlined. This course would be similar to that now pursued at the U. S. Military Academy, the Federal government cooperating with the institution in furnishing instructors and equipment. Such a course would have considerable military value and would cer- tainly be useful also from a purely civil point of view. It could be readily inaugurated and the expense would be inconsiderable in comparison with the benefits. Schools having such depart- ments could afford some of the tactical and technical training which the profession of military engineering demands. rhe problem of effectively reaching the graduates or practicing engineers is more difficult. It might be accomplished by an application of the "business men's camp" experiment, such as was conducted recently at Plattsburg, N. Y., and at other places. The greatest difficulty in the way of success is that of attendance. This, of course, nmst be entirely voluntary, and is in the hands of the engineers themselves and of their employers. It is prob- able that many patriotic employers, if they could be made to realize the great need for and importance of such training, would pledge themselves to grant leave with pay to engineers desiring to attend the instruction. It is unfortunately true that under our present military policy we must appeal to and rely largely for success on the patriotic spirit of individual citizens. The burden is thus unequally distributed and must always be unless compulsory service is adopted. The federal, state and municipal governments, which employ large numbers of civilian engineers, might well set a good example in this way by making it possible for their technical employees to attend such instruction camps. If systematic attendance can be secured all other difficulties in the 156 THE ENGINEER IN WAR way of a reasonable measure of success may be overcome. To obtain the best results, Congressional action would probably be necessary. There would be many details to work out, but the scheme holds some promise of success and is at least worth an experiment. The writer is aware that from the point of view of efficiency the scheme has disadvantages in common with all other schemes based on voluntary service. But we must face condi- tions as we j&nd them and do the best we can under the difficulties that exist. Rational preparedness for defense is necessary for the maintenance of peace and dignity — indeed for the assurance of our continued national existence. As our late Secretary of War has pointed out, if we wish to avoid compulsory service on the one hand and almost utter defenselessness on the other, our citizens must prove that a voluntary system based on patriotism can be relied upon to insure adequate defense, even if it does not provide the best possible defense. Field training in military engineering has been developed to a high degree of practical efficiency in the regular army and, under the supervision of officers of the Corps of Engineers, can be readily adapted to the instruction of civilians. The govern- ment owns or may obtain the use of tracts of land suitable for the instruction camps in the vicinity of many large cities, such as New York, Chicago, San Francisco, St. Paul and MinneapoHs, Kansas City, Washington, etc. The engineers resident in such cities could thus reach the camp at a small expense in time and money. Each camp would be in charge of several regular engi- neer officers with a detachment of engineer troops and the necessary equipment in the way of instruments, tools and materials. The course of instruction should be prepared in advance and should be varied and progressive to stimulate interest while carefully avoiding ennui or unnecessary fatigue. As in the school training, previously referred to, it should be along both tactical and technical lines. The details of camp life and the operations of field engineering are essentially interesting and the course of MILITARY OBLIGATIONS OF CITIZENSHIP 157 instruction, if intelligently carried out, would leave on the students the impression of having enjoyed a profitable and pleasant vacation, and this would go far toward insuring their attendance at subsequent sessions. More advanced courses would be prepared for men in attendance at their second or third encampment. The instruction should properly be extended over several encampments. It would include camping methods, camp administration and sanitation, simple infantry drill and the manual or arms, marches, security measures in camp and on the march, battle exercises, target practice, and instruction in practical military engineering along the lines heretofore dis- cussed. The instruction would include examinations and discussions of previously constructed works, demonstrations by the regular detachment, the actual construction of simple bridges, sections of road, trenches, obstacles, etc., the use of the ponton equipage, demolition and sketching by the students themselves, the solution of simple tactical problems, including in particular the selection and organization of a defensive posi- tion, the writing of orders, lectures, critiques and discussions. A very simple course of instruction along these general lines would require several successive encampments. Such a course would not make expert military engineers of the students, but it would afford* them a practical conception of military methods, show them how much there is to be learned, and stimulate their interest in military affairs. They would undoubtedly be- come more valuable as a military asset than perfectly green men having no conception of the nature of military operations. This field training could advantageously be supplemented by a correspondence course of practical problems in miUtary tactics, map reading, and mihtary engineering, accompanied by a course of reading. Reading alone would be of little value, inasmuch as we obtain no mental training when another does our thinking for us, and even the knowledge acquired is quickly forgotten. It is experience and responsibility that develop judgment, initiative and the power of decision. When a student 158 THE ENGINEER IN WAR reads a text-book on the art of war the responsibility for the facts alleged and the deductions made rests entirely upon the , author. From such works the student temporarily acquires a . certain amount of information, but he certainly assumes no mental responsibility and without this he receives no training. When, however, he undertakes the independent solution of a practical problem, whether in the field or at his desk, the re- sponsibility rests upon his shoulders alone and the results he obtains are impressed upon his mind as practical experience. These principles should form the basis of the instruction in the field work and correspondence courses. Reading is indeed of value but has its greatest value in connection with original and independent effort on the part of the student. The solution of these practical military problems, whether on a map or in the field, constitutes what is known as the applicatory method of military instruction. It is the method which is ptinsucd by all modern armies, being properly regarded as the best sub- stitute possible in time of peace for the actual experiences of war. Without doubt this study is one of the most stimulating and entertaining of mental activities. A brief survey of the method will therefore be of interest. The problem as stated sets forth the situation of or circumstances surrounding a certain imaginarj^ body of troops of which the student is assumed to be the supreme or one of the subordinate commanders. The statement covers the position and strength of the friendly troops, the local conditions as to terrain, weather, etc., certain information concerning the enemy, usuall}^ more or less incomplete and inexact, the orders and instructions of higher authority, etc. From a careful consideration of all this information the com- mander shapes his course of action. He first determines his mission or purpose. Often this will be embodied in the orders he has received, but circumstances may arise which compel him to disregard orders which did not contemplate these circum- stances. His mission must then be deduced from his knowledge of the situation as a whole and of the wishes or intention of his MILITARY OBLIGATIONS OF CITIZENSHIP 159 superior. It may demand a course of action at variance with the orders he has received and it is here that his judgment is called into play. Having determined his mission, the com- mander reviews the various courses open to him and comes to a decision on the course which appears to offer the greatest promise of success. This decision will require a rapid but thorough consideration of all the possibiUties of the situation. He next prepares the details of a plan for carrying out his decision and finally embodies this plan in orders to his subordinates. The review or estimate of the situation, the deduction of the true mission, the arrival at a decision, and the preparation of the plan and orders constitute the solution of the problem. These interesting and instructive mental processes will be no innovation in the brain of any thinking man, inasmuch as they are char- acteristic, not only of military problems, but of all the serious affairs of life. Individuals who had received training of this nature in college, or who had attended a certain stipulated number of instruction periods in camp, or both, should be given an opportunity to qualify by suitable examination for a commission in the volunteer engineers. Such a commission might properly carry with it a small allowance to be paid by the federal government. The possibility of obtaining such a commission would have a stimu- lating effect, especially amongst the younger men since, even without a money allowance, it would constitute an honorable distinction. The man who, while pursuing a civil calling, still recognizes the obligations of his citizenship and endeavors, even to a small degree, to fit himself for the discharge of those obligations, is and should be recognized as the best type of practi- cal patriot. Such men are the real patriots on whom alone we can rely with any degree of confidence for the maintenance of the national defense. The writer believes that there are many such men amongst our engineers and contractors and that the nation would do well to afford them the necessary training, which they are ready to receive but can not obtain without assistance. 160 THE ENGINEER IN WAR The educational schemes which have been outlined are to be regarded as tentative only. Their details have not been worked out and they are undoubtedly incomplete and perhaps faulty in many respects. The writer does not urge them as a policy to be adopted. Such a policy must be based on careful study by our governmental and military authorities, assisted by the civil profession. But whatever policy may be adopted for the mobili- zation of our resources in engineering personnel it will depend for its success on the interest and volimtary cooperation of the civil engineers of America. If, actuated by a spirit of practical patriotism, our engineers desire to better prepare themselves to meet the obligations of citizenship in the defense of their country, means can be found to give them a portion of the training of which they are in need. MILITARY OBLIGATIONS OF CITIZENSHIP 161 Field signal tower, U. S. Army. BIBLIOGRAPHY WAR DEPARTMENT OFFICE OF THE CHIEF OF ENGINEERS Washington, November 27, 1915 Military Reading for Civilian Engineers By authority of the Secretary of War, and in response to frequent requests, the following suggested list of reading is pub- lished for the information of civilian engineers desiring to inform themselves on mihtary subjects: These references have been selected, first, with a view to giving to engineers unfamiliar with the art of war, a general survey of that subject — an understanding of which is the first essential to insure successful application of engineering knowledge and resources to military purposes; and, second, with a view to setting forth, as far as practicable, the ways in which engineering is applied to military purposes and the means provided therefor. Both military art and military engineering are progressive, and a considerable part of the latest and most detailed information published is available only in service journals of our own and for- eign armies. This is particularly true of technical details of seacoast defense (including submarine mining), of field artillery, of military aviation, and the influence of these on military en- gineering. It is believed, however, that the fundamentals of each subject are well covered by the references given in this list. While the list is long, the relative importance of the various works is indicated, and suitable comments on each are included, so that persons using the lists of references may be able to select those which particularly interest them. The references under each subject are generally divided into two groups, the first containing the more essential references, and 162 BIBLIOGRAPHY 163 the second those suitable for persons desiring to inquire further into the subject. Note. — The following abbreviations are used: Supt. of Docs. — Superintendent of Documents, Government Printing Office, Washington, D. C. Book Dept. — Book Department, Army Service Schools, Fort Leaven- worth, Kans. "A»' MILITARY POLICY, CONDUCT OF WAR, AND MILITARY HISTORY Group I (1) Official Bulletin, Vol. I, No. 2, Office of the Chief of Staff, Washington, D. C. (Especially pp. 21-39,) Publisher: Army War College, Washington, D. C, Free. (An official outline of the theory under which our forces are to be organized and administered.) (2) Military PoUcy of the United States. — Upton. May be obtained from Supt. of Docs.; paper 50 cents; cloth 65 cents. (A most valuable and comprehensive review of this subject.) (3) Field Service Regulations, 1914. May be obtained from Supt. of Docs.; 60 cents. (A condensed official statement of principles, methods, and details of military operations.) (4) Elements of Strategy. — Fiebeger. Publisher: U. S. Military Academy, West Point, N. Y. May be obtained from Book Dept. ; 75 cents. (A short outline, with historical illustrations.) Group n (5) Conduct of War. — Von der Goltz; translated by J. T. Dickman; Hudson Publishing Co., Kansas City, Mo. May be obtained from Book Dept.; $1.70. (The standard work on this subject, covering generally the same ground as (4), but more abstractly and elaborately.) (6) On War. — Clausewitz; translated by J. J. Graham; 3 vols.; K. Paul, Trench, Trubner & Co., 1908. May be obtained from Book Dept. ; $6.60 (including postage and duty). (The greatest classic on the subject; a complete analysis of the phenomenon of war, and pro- found discussion of the mechanism thereof. Written early in the 19th Century, it is still the foundation of modern miUtary theory.) (7) American Campaigns. — M. F. Steele; 2 vols.; Publishers: Byron S. 164 THE ENGINEER IN WAR Adams Publishing Co., Washington, D. C. May be obtained from Book Dept.; $4.50. (In addition to careful historical sur- veys of all the campaigns from the Colonial Wars to the Spanish American War, these lectures give extensive and valuable com- ments as to the military principles.) (8) A study of Attacks on Fortified Harbors. — Rodgers; Proceedings Nos. Ill, 112, and 113, U. S. Naval Institute, Annapolis, Md. (9) Lessons of the War with Spain. — Mahan. Publishers: Little, Brown & Co., Boston, Mass. May be obtained from Book Dept.; S2.00. (Of special importance, as showing the true relation between our coast defense and our navy.) (10) Reports of Military Observers on the Russo-Japanese War. Part 111. — J. E. Kuhn. May be obtained from Supt. of Docs.; 60 cents. (In addition to an account of operations, this report contains valu- able information as to fortification and siege work, organization, and equipment.) (11) Organization and Operation of the Lines of Communications in War. — Furse, 1894. Publishers: Wm. Clowes & Sons., Ltd., London. (An old but comprehensive survey of this subject, with much his- torical information.) "B" PERMANENT FORTIFICATIONS Group I (The references given cover chiefly the principles and general features of this subject; the details are mostly printed in unavailable form, either in service journals or in confidential documents. References to some of the former can be furnished, if desired.) (12) Report of National Coast Defense (Taft) Board, 1906. May be obtained from Army War College, Washington, D. C. Froe. (The official project for harbor defenses of the United States. On account of progressive obsolescence of seacoast defenses, this project has been, or is being, modified, but still sets forth clearly the fundamentals of its subject.) Group n (13) Lectures on Seacoast Defense. — Winslow. Publishers: U. S. Engineer School, Washington Barracks, D. C. Price 50 cents. (Much of these lectures relates to technical details, and a considerable part is now obsolete.) BIBLIOGRAPHY 165 (14) Permanent Fortifications. — Fiebeger, 1900; U. S. Military Academy, West Point, N. Y.; $1.00. May be obtained from Book Dept. (While rather old, this work gives a simple presentation of the fundamentals of its subject, including an historical outline. A revised edition will soon be published.) (15) Fortification.— G. S. Clarke; Button & Co., New York; $4.50. May be obtained from Book Dept. (A treatise on the same lines as (14)). (16) Principles of Land Defense. — Thuillier, 1902; Longmans, Green & Co. May be obtained from Book Dept.; $3.83. (A very valuable work, covering the principles of both field and permanent forti- fication.) (Probably the best single work on the subject. — P. S. B.) "C" ORGANIZATION, EQUIPMENT, AND DUTIES OF ENGINEER TROOPS Group I (17) Field Service Regulations, 1914. (See "A" 3.) (18) Tables of Organization, 1914. May be obtained from Supt. of Docs.; 25 cents. (These tables represent — subject to modification and within the limits of existing law — the approved policy of the War Department with regard to organization.) (19) Official Bulletin, Office of the Chief of the Staff, Vol. I, No. 4 (Ap- pendix 4.) Use of Engineer Troops. Publisher: Army War Col- lege, Washington, D. C. Free. (An official statement of the principles which should govern in the use of engineers, with practical suggestions.) (20) Duties of Engineer Troops in a General Engagement of a Mixed Force — Burgess. Publisher: U. S. Engineer School, Washington Barracks, D. C; 25 cents. (Obsolete in some respects, particu- larly organization, but excellent in general scope.) (21) General Orders No. 6, War Department, 1915. May be obtained from The Adjutant General, U. S. Army, Washington, D. C. Free. (Prescribes the training of Engineer troops.) Group n (22) Studies in Minor Tactics. — Army Service Schools, 1915. May be obtained from Book Dept.; 50 cents. (The principles of Minor Tactics are set forth by solution of a series of problems.) (23) Technique of Modern Tactics. — Bond & McDonough, 1914; Banta Publishing Co., Menasha, Wis. May be obtained from Book 166 THE ENGINEER IN WAR Dept.; $2.55. (This work covers, in a very specific way, the principles of tactics for all arms, a general knowledge of which is essential for engineers.) (24) Operation Orders. — Von Kiesling; translation. May be obtained from Book Dept. ; 50 cents. (A lucid exposition, by use of assumed cases, of the operation of highly trained troops of all arms in various phases of battle.) (25) Engineer Unit Accountability Manual. May be obtained from Supt. of Docs. ; 5 cents. (Official lists of standard equipment supplied to engineer battahons and companies.) (26) Organization of the Bridge Equipage of the U. S. Army, 1915. (Re- vised edition just going to press.) (Includes description of equi- page and regulations for ponton drill.) (27) Officers' Manual. — Moss; Banta Publishing Co., Menasha, Wis.; $2.50. May be obtained from Book Dept. (Treats of routine duties of officers, customs of the service, army organization, etc.) (28) Manual for Courts Martial. May be obtained from Supt. of Docs.; 50 cents. "D" FIELD ENGINEERING MiUtary field engineering at the front differs from ordinary engineering work in the field, in being generally simpler, of a rough-and-ready character, and especially because of the limited equipment which can be taken along with the advance of an army, and because of the necessity of working in strict subordination to the military situation. In rear of the army, on the con- trary, conditions are very similar to those governing ordinary engineering operations, and civilian organization is suitable, subject to directions by the higher military staflf. Little attempt is made in works on military field engineering to treat of general engineering methods.) (29) Field Fortification.— Fiebeger, 1913; John Wiley & Sons, New York. May be obtained from Book Dept.; $1.90. (In addition to tech- nical details, this work gives valuable historical illustrations of the principles of this subject.) (30) Field Entrenchments, Spade Work for Riflemen. — John Murray, London. May be obtained from Book Dept. ; 40 cents. (A very up-to-date little work; especially on details.) (31) Notes on Field Fortification. — Army Field Engineer School. May be obtained from Book Dept. ; 30 cents. (32) Engineer Field Manual. — Professional Papers No. 29, Corps of Engi- neers, U. S. Army; 3d edition, 1909, 500 pages. May be obtained from Supt. of Docs., $1.00. (A very complete official pocketbook for engineer officers in the field, containing much tabular and tech- BIBLIOGRAPHY 167 nical data, as well as brief outlines of principles and methods. The subjects covered are: Part I, Reconnaissance; Part II, Bridges; Part III, Roads; Part IV, Railroads; Part V, Field Fortification, and Part VI, Animal Transportation. A new revision of the manual is contemplated, but will not be ready within a year. The portion of the manual relating to Field Fortification, being some- what obsolete, should be considered in connection with either (30) or (31) above. The portion relating to Railroads is largely super- seded by (35) below. (33) Notes on Bridges and Bridging. — Spalding. May be obtained from Book Dept. (A small pamphlet on military bridging.) (34) Military Topography for Mobile Forces. — Sherrill, 2d Edition; Banta Publishing Co., Menasha, Wis., 1911. May be obtained from Book Dept.; $2,25. (Besides matter given in ordinary text-books on surveying, this work gives in detail the special methods of sketching developed in the army for rapid military mapping.) (35) Military Railroads.-^Connor; Professional Papers No. 32, Corps of Engineers, U. S. Army; Supt. of Docs.; 50 cents. (Intended to cover general administration of existing railroads for military purposes and the handling of railroads by military personnel in the advanced sections where railroads can not be operated by their regular civilian organizations, or where new railroads are required in the immediate vicinity of the Army. Revised edition soon to appear.) (36) Notes on Military Explosives. — Weaver: J. Wiley & Sons, New York; 1912. May be obtained from Book Dept.; $2.20. (Elementary notes on this subject will be found in the Engineer Field Manual and other references cited. This work is more elaborate.) "E" ' MISCELLANEOUS (37) Regulations for the Army of the United States; Supt. of Docs.; 50 cents. (38) The ''Volunteer Law," approved April 25, 1914; Bulletin No. 17, War Department, 1914. May be obtained from The Adjutant General, U. S. Army, Washington, D. C. Free. (39) General Orders No. 54, War Department, 1914. May be obtained from The Adjutant General, U. S. Army, Washington, D. C. Free. (Covers examination of candidates for commissions as officers of volunteers.) (40) General Orders No. 50, War Department, 1915. May be obtained from The Adjutant General, U. S. Army, Washington, D. C. Free. 168 THE ENGINEER IN WAR (Amends General Orders 54, 1914, as to examination of candidates for commissions in volunteer engineers.) (41) Treatise on Military Law. — Davis; J. Wiley & Sons, New York. May be obtained from Book Dept. ; $5.30. (42) Elements of Military Hygiene. — Ashbume; new edition; Houghton, Mifflin & Co., Boston, 1915. May be obtained from Book Dept.; $1.30. "F" PERIODICALS (43) Professional Memoirs, Corps of Engineers, U. S. A., and Engineer Department at Large; Bi-monthly (formerly quarterly); Wash- ington Barracks, D. C, Engineer Press; per year, $3.00. (44) The Royal Engineers* Journal. — Royal Engineers' Institute, Chatham, England; Monthly; per year $4.00. (American agents, E. Steiger & Co., 49 Murray St., New York.) (45) Journal of the Military Service Institution, Governors Island, New York. Bi-monthly; published by the Institution; per yaer $3.00. (46) Journal of the United States Artillery; Bi-monthly; Fort Monroe, Va., Coast Artillery School Press; per year $2.75, including Index to Current Literature; without Index, $2.50. (47) Journal of the United States Cavalry Association; published by the Association at Fort Leavenworth, Kans.; per year $2.50. (48) Infantry Journal; Bi-monthly; published by the U. S. Infantry Asso- ciation, Union Trust Building, Washington,^ D. C; per year $3.00. (49) Field Artillery Journal; quarterly; published by the U. S. Field Artil- lery Association, 601 Star Building, Washington, D. C; per year $3.00. In addition to the foregoing list, issued by the War Dept., the following text-books will be found of interest: (50) The Nation in Arms.— Von der Goltz. Book Dept., $2.50. (An exposition of the modem theory of war, very readable and inter- esting.) (51) Letters on Applied Tactics (with maps). — Griepenkerl. Book Dept., $1.70. (A standard German work on minor tactics, the principles being well presented by a series of problems and solutions.) (52)'Dutics of the General Staff.— Von Schellendorf. Book Dept., $1.85. (A German work probably the best on this subject.) (53), The Rifle in War.— Eames. Book Dept., $1.70. (A theoretical and practical investigation of the effects of rifle fire in battle.) (54) Manual of Military Field Engineering. — Beach. Book Dept., 90 cents. (For many years the best American manual. It is now largely BIBLIOGRAPHY 169 superseded by the Engineer Field Manual (32) but is still of interest and value.) (55) Examination and Repair of Simple Highway Bridges. — Sherrill. (A pamphlet of the Book Dept.) (56) Military Demolitions. — MacArthur. (A pamphlet of the Book Dept.) (57) Individual and Combined Military Sketching. — Cole and Stuart. Book Dept., 95 cents. (Describes the methods for hasty mapping of relatively large areas under war conditions.) GLOSSARY OF MILITARY TERMS EMPLOYED IN THE TEXT Abattis. — An obstacle consisting of felled trees, often interlaced with wire. The trees are felled or placed with their tops toward the enemy. Applicatory method. — A system of military peace training by means of the solution of practical problems in strategy and tactics. These problems are solved on a map or on the terrain, and are called ''map problems" and ** terrain exercises." Artillery. — The heavier pieces of ordnance, as distinguished from small- arms and machine guns. Artillery includes guns, howitzers and mortars of various calibers. All modern artillery is rifled. Mobile artillery is habitu- ally mounted, both for transport and use, on wheeled carriages, and accom- panies the mobile troops. Balk. — A bridge stringer. Commonly applied to the stringers of the ponton equipage. Battalion. — A unit of army organization consisting of several companies, usually four. Bomb-proof. — A shelter, usually subterranean, against high-explosive shell. Chess. — The deck plank of the portable bridge equipage. Chevaux-de-frise. — An o!)stacle in the form of a saw-horse with several legs. Clinometer. — A small hand instrument used to measure the inclination or slope of the ground. Communications. — The prepared routes by which troops move from one part of a position to another; also their lines of supply and reinforce- ment. The term is also applied to telegraph, telephone and other signalling apparatus. Concentration camp. — A camp at which troops are assembled for purposes of training. Corduroy. — Logs or slabs laid crosswise to form a road on swampy ground. Counter-attack. — Offensive operations by troops whose general attitude is or has been defensive. Counter-mining. — The subterranean operations of troops on the defensive for the purpose of frustrating the efforts of the attack. 170 GLOSSARY 171 Cover. — Protection from fire and view. Declinator. — A magnetic needle attached to the edge of a sketching board for the purpose of orientation. Defensive position. — A line or belt of the terrain occupied by troops and prepared for defense by means of field fortifications. Delaying action. — A combat entered into for the purpose of temporarily delaying the enemy. Demolition. — The destruction of material objects by any means. Detonator. — A small charge of explosive used to ignite a larger charge. Division. — A unit of army organization, the smallest which includes all branches of the service. In the United States Army a division has a strength of about 20,000. It includes infantry, cavalry and field artillery and the necessary special troops such as engineers, signal, medical and sanitary, etc., with all the requisite wagon or motor transport. Enfilade. — Fire from the flank, parallel or nearly parallel to the line against which it is directed. It is peculiarly eflfective and demoralizing and is always carefully guarded against. Estimate of the situation. — A mental review of existing conditions and circumstances on which a commander bases his plans. Fascine. — A long cyhndrical bundle of brush used as a revetment. Fire superiority. — Superior moral or physical fire effect as compared to that of the adversary. Fire superiority is implied if the assailant can ad- vance or force back the defender. Fire superiority for the defender is implied if he can hold his ground and check the advance of the assailant. Fixed ammunition. — Ammunition in which the projectile and propelling charge are a single piece, the charge being contained in a metal case with the projectile fixed in the end like a rifle cartridge. It is used in all small arms and machine guns and in many of the smaller field guns and howitzers. Flanks. — The extremities of a defensive line and the ground in their vicinity. Flying ferry. — A ferry in which the float is swung from bank to bank by means of a line anchored upstream. Fortification. — Any engineering work or accessory device which increases the fighting power of troops by affording shelter or concealment or increased fire effect, or which restricts the tactical maneuvers or fire effect of the enemy. Fortification, field or hasty. — Those works executed by combatant troops in the field to meet immediate tactical needs. Fougasse. — A small land mine with a charge of explosive and broken stone. It is fired by powder fuse or electricity as the enemy approaches. Fuse. — A device used for detonating the explosive charge of a shell or shrapnel. Fuses are classified as time, percussion, combination (percussion and time) and delayed action. Time fuses detonate at the end of a given 172 THE ENGINEER IN WAR time, percussion fuses on impact. A delayed action fuse is one which delays the explosion of the charge until the projectile has penetrated the structure which it strikes. The term fuse is also applied to powder trains used to ignite placed charges of explosive in demolition. Electric fuses are devices which detonate a charge by means of the heating efifect of an electric cur- rent. They are also called primers. Gabion. — A hollow cylinder of brush or other material which is filled with earth and used as a revetment. General Staff. — A corps of highly trained officers charged with the study of the conduct of war and the detailed methods of military operations. In time of war they direct and administer the operations of mobilization, con- centration, supply, transportation, etc., and assist the field commanders in planning and executing their operations. Grenade. — A charge of high explosive in a container hurled a relatively short distance by hand or by means of a catapult, rifle, or small mortar. The charge explodes by time-fuse or on impact. Large grenades are called air-mines or air-torpedoes. They are distinguished from high explosive shell by their relatively short range, which ordinarily does not exceed 500 yards. Gun. — A piece of ordnance fired from a platform or wheeled mount. A gun, as compared with a howitzer, has a relatively long barrel, flat trajectory and high velocity. Its effect is produced largely by the vigor of the blow struck by the projectile, which may be combined with the action of a charge of explosive. Guns, according to their size and uses, are classed as moun- tain, light or heavy field, siege and seacoast. All modern guns are breech- loading rifles. ^ Head cover. — A vertical shield of any material which protects the heads of tlie troops from fire. High explosive shell. — A projectile containing a charge of high explosive fired from a gun or howitzer. The charge explodes by time fuse or upon impact. It is used principally to demolish material objects, such as fortifi- cations, and is seldom employed against troops in the open, being for this purpose less effective than shrapnel. Howitzer. — A piece of ordnance having, as compared with a gun, a short barrel and curved trajectory. Its effect is produced chiefly by the explosion of the charge contained in the projectile. (See mortar.) Hurdle. — A revetment of woven brush. Initiative. — A commander is said to have the initiative when he carries out a preconceived plan, dictating and controlling the course of operations and forcing the adversary to meet his lead. The initiative is ordinarily, though not always, possessed by the attacker, inasmuch as he usually selects the time, place and manner of attack, and forces the defender to adapt his GLOSSARY 173 measures to meet it. A vigorous counter-attack, which forces a suspension of the attack, transfers the initiative to the original defender. Latrine. — A dry sewage pit or trench; a cesspool. Line. — A general term applied to all combatant troops; a position occupied by troops, as a defensive line. Line of investment. — A cordon of troops drawn around a fortress for the purpose of cutting off its supply and communication; usually the first step in siege operations. Listening galleries. — Subterranean galleries driven to the front for the purpose of detecting the mining operations of the enemy. Listening posts. — Sheltered positions in advance of a defensive line for the purpose of early detection of the enemy's movements. They are connected with tlie main line by a communicating trench or subterranean gallery. Loop-holes. — Openings in a parapet or head cover through which fire is delivered. Machine gun. — An automatic or semi-automatic gun of small caliber capable of great rapidity of fire. It uses fixed ammunition, preferably identical with that emf)loyed in small arms. The ammunition is fed auto- matically from a hopper, clip or belt. Maneuver. — A movement of a body of troops. Strategical maneuvers include movements of troops, on a relatively large scale, in preparation for prospective battle, but usually at a distance from the enemy. Tactical maneuvers include movements executed on the battlefield or in the near presence of the enemy. As compared with strategical maneuvers they are usually on a smaller scale, in closer proximity to the enemy, and more im- mediately related to battle tactics. Map distance. — The horizontal interval between contours (on the map) corresponding to a given slope or gradient. Mining. — The operations of subterranean attack. Mobility. — The power of rapid movement. Mobile troops are those capable of quickly changing their location and dispositions to meet tactical needs. Non-mobile troops are capable only of passive defense. It is there- fore essential that first-line troops shall be highly mobile. Otherwise they can not seize or retain the initiative. Even in defensive operations mobility is essential to mfeet the movements of the assailant. Mobilization. — The change from peace to war footing. An army is said to be mobilized when it is assembled, armed and equipped, and organized to take the field. Morale. — The collective psychological condition or spirit of troops, espe- cially combatant troops engaged in battle. High morale is implied when troops respond readily to the will of their commander. Morale is therefore measured by the extent to which troops submit to the control of their officers. 174 THE ENGINEER IN WAR Mortar. — A piece of ordnance having a very short barrel and curved trajectory. It throws a projectile containing a large charge of high explosive. Normal system. — A system of scales and contour intervals so arranged that a certain map distance represents the same slope whatever the scale of the map. Observation posts. — (See listening posts.) Observation posts may also occupy commanding positions in rear of the firing line. Obstacle. — Any device which retards the enemy's movements without affording him shelter from fire. Ordnance. — A collective term applied to all firearms which hurl projec- tiles. As generally used the term excludes "small arms," such as rifles and pistols, and applies especially to the heavier pieces. (See small-arms and artillery.) Outpost. — A line of observation and resistance established between a body of troops and the known or supposed position of the enemy to guard against surprise attacks. Overhead cover. — A horizontal or inclined shield of any material which ex- tends over tlie heads of the troops and protects them from high angle fire. Pace tally. — An instrument for counting paces. Pack train. — .\ train of animals, usually mules, carrying packs on saddles. This form of transportation is used in mountainous country or wh§re roads are very poor. Parados. — A bank of earth in rear of a trench to protect the occupants from the back draft of shells bursting behind the trench. Parapet. — A bank of earth or other material in front of a trench or em- placement which protects the occupants from fire. Pioneer. — A member of the mobile engineer forces of an army. Plane table, military. — A small plane table or sketching board used in military mapping. Ponton. — A portable boat used as a support or pier for a floating bridge. Ponton equipage. — The portable floating bridge equipment of an army. Principal sketcher. — One who coordinates and controls the work of a number of individuals in combined sketching. Reconnaissance. — A rapid examination of a structure, locality, district, etc., for the purpose of noting features and gathering information of military value. Reserves. — Troops temporarily withheld from action for the purpose of reinforcement at critical times and places. Also individuals who have undergone military training and are aoailahle for service but not at the time a part of the standing army. GLOSSARY 175 Revetment. — Any device used to hold earth or other material at a slope steeper than the natural slope. Shrapnel. — A projectile containing a number of small bullets or fragments with a propelling charge. It explodes in the air and scatters the bullets and fragments of the case over a considerable area, being in effect a flying shotgun. The shrapnel of the 3-in. U. S. field gun, when properly burst, will sweep an area 200 to 300 yards in depth and 20 to 25 yards in width, killing or seriously wounding any man or animal in the area. It has little effect on fortifications and is used only against troops. Shrapnel is hence known as the "man-killing projectile." Siege. — The formal investment and attack of a fortress. Sketch, area or position. — A hasty military map of an area of ground ** showing the contours and all natural and cultural features of military significance. Sketch, landscape. — ^A pictorial representation of a landscape. Sketch, military. — A term applied to a hastily constructed map prepared in tho field for military uses. Sketch, place. — An area sketch executed from a single station where the sketcher does not have access to the terrain portrayed. Sketch, road. — A hasty map showing the route of a road and the nearby topography. Sketching board. — See plane table. Sketching, combined. — Military mapping in which an area is divided into sections to be mapped by individuals, the results being subsequently combined. Sketching, individual. — Military mapping operations where each indi- vidual operates independently. Small-arms. — Firearms, such as rifles and pistols, carried by individuals. The term is occasionally applied also to machine guns which use small-arms cartridges. Spar bridge. — A type of military bridge in which the support consists of two trestles which are tilted toward each other and locked together. Splinter-proof. — A shelter similar to a bomb-proof but designed to afford protection only against rifle bullets, shrapnel and shell fragments. It is not proof against penetration by large projectiles. Strategy. — The application of the broad fundamental principles of the art of war. The object of strategy is to place troops in the most favorable or least unfavorable position for battle, which is the culmination of strategy. Strategy deals with questions of national policy, national resources, geogra- phy, mobilization and concentration of troops, supply, transportation, etc. Supports. — Troops held in rear of the firing line for the purpose of replac- ing losses. 176 THE ENGINEER IN WAR j Tactics. — The methods employed in handling troops in battle or immediate preparation therefor. Terrain. — An area of ground considered as to its extent and topograp | in relation to its use for a specific purpose, as for a battle or the erection | fortifications. ' Theater of war. — The territory covered by the operations of belligef forces. Trajectory. — The path of a projectile. Guns of high power are said have a flat trajectory, that is to say, one which approaches a straight linf Traverse. — A bank of earth or other material in rear of and perpendicu to the parapet for the purpose of protecting the occupants from oblique enfilade fire and to localize the effect of shells bursting in the trench. Trenches. — The purpose of trenches is to protect the troops occupy] them from hostile fire. According to their use they are classified as fij support and communicating trenches. Wire entanglement. — An obstacle of wire or barbed wire strung on po or other supports; the most commonjy employed obstacle. INDEX (Bold face figures denote general treatment of subjects.) bbatis, 93 abutment sills — see Bridges, 43 ctinic printing processes, 127 ilignment, of roads, 64, 66, 67, 68 inchorage — ponton bridges, 37, 43 inchorages — suspension bridges, 53 meroid barometer, 69, 118, 120, 126 mgles, measurement of, 118, 119 kpplicatory system of military in- struction, 158, 159, 160 Lrclies — demolition, 112 ^rca or distance sketched in a day, 126 Artillery, 57, 61, 73, 74, 76, 96, 101, 102, .03, 106, 131 Usault of sic t^e works, 100, 104 Atlantic seaboard: industries and population, 7 probable theatre of war, 7 Uitomobiles- see Motor trucks. Balk of ponton equipage, 37, 43 Bamboo bridges, 48 Barometer, aneroid, 69, 118, 120, 126 Battlefield, illumination of, 94, 96 enham. Gen. H. W., quoted, 44, 45 ismarck, 3 oiling of water, 139 ombardment of a fortress, 103 [Bombs, illuminating, 96 Bomb-proof shelters, 84 Bridges, 15, 19, 20, 22, 26, 36, 122, 125, 131 bamboo, 48 12 177 Bridges, bracing of, 47, 48 combination of types, 54, 56 crib, 49 deck or roadway of, 37, 56, 60,- 61 demolition, 110, 112 , examination of, 60 existing, 22, 46, 60 factor of safety, 40, 60, 61 false work, 49 formula) for strength of, 60 improvised, 35, 46 lashings for, 38, 56 materials for, 35, 45, 48 pile, 48 pile drivers, 33, 48 placarding, 62 ponton, 29, 31, 37 abutments, 43 anchorage, 37, 43, 44 balk or stringers, 37, 43 buoyancy of pontons, 37, 38 chess, 37 dismantling bridge, 43 draw spans in, 44 ferriage, 57 historical example of use, 44, 45 improvised supports, 44 light and heavy, 37, 38 methods of construction, 40, 41 ponton boats, 37, 38 saddle, 37 178 INDEX Bridges, ponton, span, 38 time of construction, 38, 40, 44, 45 transportation, 38, 40 trestle spans, 37, 43, 56 weights or equipage, 40 width of deck, 38 portable — see Ponton, 37 selection of site, 47 spar, 50, 51 standard design in, 62 strength of, 60 strengthening and repair of, 46, 62 stringers, 37, 47, 56, 60, 61, 62 suspension, 62 anchorages, 53 cables, 52 construction, 53, 54 hangers, 52, 54 ^ materials employed, 52, 53 oscillation, 54 sag of cables, 53 span, 52 stiffening, 54 towers, 53 undulation, 54 trestle, 47, 48, 56 truss, 49, 50, 56 use of existing, 22, 46, 62 Buildings, 111, 122, 125 Business men's camps, 155 Buoyancy of pontons, 38 Cables, suspension bridge, 52, 53 Camps : concentration, 138 epidemics, 136 instruction, 155 location of, 15, 125, 131, 137, 138 sewage disposal, 137, 140 Camps, water supply, 131, 137 Caps, 107 Cesspools, 140 Chemical purification of water, 139 Chess, 37 Chevaux-de-frise, 93 China, military policy of, 2, 4 Cholera, 138, 139 Citizenship, military obligations of, 2, 3, 163 Civil engineering, relation to mili- tary engineering, 11, 17 Civil population of a fortress, needs of in war, 102, 146 Civilian specialists in war, 17, 33, 116 Clinometer, 69, 119 Commandeering supplies, 144, 148 Commercial standards, conformity to, 144 Commissions in volunteer engineers, 160 Communications — see Lines of com- munication, 74, 131 Compulsory service in Great Bri- tain, 5 Compulsory training: in Germany, 3 prejudice against in United States, 4, 5 Concealment, 74, 76, 85, 86 Concentration of force, 72, 73 Concrete mixers, 26, 33 Conditions governing military con- struction, 33 Contours— see Maps, 119, 120, 127, 130 Contractors, 9, 10, 22, 152, 153 Contractors' foremen, 153 Control in mapping and sketching, 116, 121, 127, 130 Conventional signs in mapping, 122 Corduroy roads, 66 INDEX 179 Correspondence courses for civilian engineers, 157, 158 Cost of engineering structures, 17, 18, 19, 20 Cost of warfare, 18 excessive, of wars of U. S., 18 Counter attack, 76 Countermining, 104 Courses of instruction for civilian engineers, 156, 157 Cover : artillery, 96 reserves, 76, 87 supports, 74, 76, 86 Cover, natural, advantages of, 86 Crib bridges, 49, Critical points in mapping, 121, 127, 130 Culverts, 70 Decisive action, selection of position for, 75 Deck or roadway of bridges, 36, 37, 38, 56, 60, 61 Defensive policy, effect of on war- fare, 7 Defensive position, 25, 74, 75, 76, 125, 131, 137 Delaying action, position for, 75 Demolition, 15, 74, 92, 99, 106 arches, 112 bridges, 110, 112 buildings, 111 by explosives, 74, 99, 106 by fire, 106, 109, 110, 112 by high explosive shell, 74, 78, 106 canal locks, 112 framed structures, 110 obstacles, 112 outfits for, 106 railroads, 109, 110, 111 Demolition, railroad, bridges, 109, 110 rolling stock. 111 track, 109, 110, 111 tunnels, 110 reconnaissance for, 108 roads, 110, 111 supplies and materials, 112 telegraph lines, 111 woods, 112 Depths, practicable, of fords, 57 Detonators, 107 Diseases : epidemic, 136 waterbome, 138 Distance or area covered by sketcher in a day, 126 Distances, measurement of, 117 Distillation, 139 Drainage: bomb-proofs, 88 camp sites, 131, 137, 138 roads, 66, 70 trenches, 82 Drainage lines in mapping, 121, 127, 130 Draw spans in ponton bridges, 44 Dressing stations, 74 Drills, portable, 33 Duties of engineers in war defined — see Engineer troops, 13 Dynamite, 107 Dysentery, 138 Economics of military engineering, 11, 17, 18, 19, 20, 21, 26, 33 Economics of military road loca- tion, 68, 69, 71 Economics of peace and war com- pared, 12, 17, 18, 19, 20 Economic span : trestle bridges, 47 180 INDEX Economic span, truss bridges, 50 Effect of war on industrj', 146, 147 Elevations, determination of, 118, 119, 120, 121 Enfilade, 89, 100 Engineering colleges, 155 Engineer officers for staflf duty, 8 Engineer troops: equipment, 28 in national guard, 8 in regular army, 8, 9 needed in case of war, 7 proportion of, 7 Engineer troops, duties of, 13 field fortification, 74, 75 Unes of communication and bases, 7, 9, 13 mapping, 114, 126 mobile army, 7, 9, 13, 16, 25 siege operations, 13 sanitation, 136 Engineering societies, 154 Entanglements, wire, 93, 112 Epidemic diseases, 136, 138 Equipment for mobile engineer troops — 8€e Tools, 26 Equipment of industrial plants, 144, 145 Estimation of slopes and distances, 114, 121 Examination of bridges, 60 Expeditionary forces which might be landed in U. S., 6 Exploders, magneto-electric, 107 Explosives, 64, 69, 74, 92, 99, 106 requirements for military uses, 107 Explosives employed in demolition, 107 dynamite fulminates gun-cotton Explosives, gun-powder jovite lyddit« melinite nitro-glycerine shimose Sprengel mixtures trinitrotoluol Factor of safety of bridges, 40, 60, 61 False work for bridges, 49 Fascines, 57 Federal control : prices and sales, 149 transportation, 148 Federal, state, and municipal em- ployees, 155 Ferries, 19, 57, 58 Field fortification, 72 concealment in, 85 correct tactical employment, 71 purposes of, 73, 74 works included under, 74 Field of fire, 76, 131 Fortification, tactical or hasty — «« Field fortification. Filters, 139 Fire superiority, 76 Fire, use of in demolition, 106, 109 110, 112 Flanks, 76, 131 Flies, 138, 140 Floor or deck of bridges : strength, 60, 61 width, 38, 56 Foreground : illumination of, 92, 93 preparation of, 92, 93 Fords, 66, 125, 131 practicable depths, 57 Formulae for strength of bridges, tiO 61, 62 INDEX 181 Fortification — see Field fortification, 14, 72 Fortification : effect of weapons employed, 74 purpose of, 74 Fortress, siege of, 100 Fougasses, 94, 95 Framed structures, 110 French, Sir John, quoted, 151 Fulminates, 107 Fuse: instantaneous, 107 time, 107 rates of burning, 107 Galleries : listening, 92 subterranean, 89, .92 General staff: Germany, 3 United States, 4, 6, 143 Geological Survey, maps of, 115, 116 Germany : compulsory regular training, 3 general staff, 3 military policy, 3, 4, 7 mobilization of resources, 3 Gradients, of military roads, 67, 68, 131 Gravel for roads, 66 Great Britain, compulsory service in, 5 Grenade nets, 82 Grenades, 82, 84 Gun-cotton, 107 Head cover, 80, 81 Hectograph, 127 Hoists, portable, 33 Hostile interference with industry, 146 Howe truss, 50, 62 Hygiene, 137 Ice, supporting power, 57 Illumination of the battle-field, 92, 93,94 Improvised bridges, 45 Improvised floats, 44 Incineration, 140 Industrial personnel, 144, 146, 147, 148, 153 Industrial plants, 142 Industrial resources, mobilization of 3, 142 Information conveyed by maps, 122, 125, 126, 131 Initiative, 72 Instruction, applicatory system of, 158, 159, 160 Instruction camps, 155, 156, 157 Instructions for fabrication of mate- rial, 146 Instruments employed in surveying and sketching and in road location : alidade, 117, 118 aneroid barometer, 69, 118, 120, 126 clinometer, 69, 119 compass, 118 declinator, 116 hand-level, 120 pace tally, 117 plane table — sketching board, 116 sextant, 118 transit, 69 Intrenching tools, 27, 28, 29 Intrenchments — see Field fortifica- tion. Inundations, 93 Investment of a fortress, 101, 102 182 INDEX Kitchen waste, 138, 140 Lashings, 30, 38, 56 Latrines, 74, 140 Line of investment, 102 Lines of communication, 7, 9, 13, 26, 33 Lining for shafts and galleries, 89, 90, 92 Listening galleries, 92 Lithography — see Map reproduction. Local resources, 13, 15, 26, 29, 125 Location of military roads, 64 Location of supports, 86 Location of works of field fortifica- tion, 15, 26, 74, 75, 99 Loopholes, 80, 85 Lyddite, 107 Machine guns, 73, 74, 96, 101 Maintenance economics of military roads, 71 Maintenance of roads, 64, 71 Makeshifts, characteristic of mili- tary engineering, 12, 16, 18, 19, 21, 141 Manufactories, location of in U. S., 146 Manufacturers' organizations, 145, 148 Map problems, 158 Map reading, 114, 130 Maps, military, 14, 15, 113 collection, compilation, repro- duction, 14, 15, 114, 126 127 construction of contoured maps, 119, 120, 127, 130 control, 116, 121, 127, 130 conventional signs, 122 Geological Survey, 115, 116 information conveyed, 122, 125, 126, 131 Maps, instruments employed, 116, 120 map distances, 119 need of maps in advance, 115 normal system, 121 reproduction methods and equipment, 15, 29, 31, 32, 126, 127 road location, use for, 69 scales for military purposes, Ho strategical maps, 115 use in warfare, 113 Material, reserves of, 29, 143 Material resources, mobilization of, 142 Materials employed in military engineering, 13, 26, 29, 30, 35, 45, 48, 49, 52, 67, 97 Medical department, 136 Melinite, 107 Mexico, 6, 35, 115 Military engineering, adaptation of civil engineering, 11, 17 Military' obligations of citizenship, 162 Military policy : China, 2, 4 Germany, 3, 7 Military policy of United States. 1 Military strength as distinguished from resources, 1, 2 Militar>' training at colleges, 155 Mines, 94, 95 Mining, military, 74, 89, 92 Mission controls selection of posi tion, 75 Mission, defined, 158 Mobile army, duty of engineers witl 13 Mobility, 25, 28, 35, 63, 72, 86] Mobilization of industrial personni 146 INDEX 183 Mobilization of material resources — Germany, 3 Mobilization of material and indus- trial resources, 142 advantages enjoyed by United States, 151 ascertaining probable needs, 142 assistance of engineering profes- sion, 147, 148, 150 association of manufacturers, 145, 148 cessation of industry, 147 classes of supplies, 143 closing of markets in war, 147 commandeering supplies, 144, 148 conformity to commercial stan- dards, 144 effect of shortage of supplies on military operations, 150, 151 employment of women, 146 equipment of industrial plants, 144 experiences of European war, 142 experimental samples, 145 federal control of transporta- tion, 148 • federal regulation of sales, 149 governmental aid, 147 government munition plants, 149 hostile interference, 146 instructions for fabrication, 145 investigation of industrial plants, 144 labor unions, 148 location of plants on seaboard, 146 Mobilization, mobilization of indus- trial personnel, 146 mobilization plans and data, 143, 149 needs of civil population, 146 personnel of railroads, 148 plans and specifications for war material, 145 prices for war material, 149 rate of output, 146 reserves of material, 143 sources of supply, 142, 143 stimulative measures, 143, 145 supplies needed, 142 tools, machines and gauges, 145 training of industrial personnel, 144 transition from peace to war, 147 transportation systems, 142, 148 United States self-supporting, 147 Mobilization plans and data, 143, 149 Modem theory of war, 2, 1 1 Monroe Doctrine, 6 Motor trucks, 30, 32, 63, 65, 143 Mounted section, 31 Munition plants: federal, 149 private, 144, 145, 146 Napoleon, quoted, 9, 28, 35 National guard : engineer troops in, 8 strength of, 5 training of, 4 Natural features of terrain utilized in fortification, 86 New York, engineer troops of national guard, 8 184 INDEX Nitro-glycerine, 107 Non-commissioned oflBcers, 23, 130, 153 Normal system of maps, 121 Obligation of service, 2, 3, 163 Observing stations, 74, 131 Obstacles, 15, 74, 76. 93, 112, 131 Ohio, engineer troops in national guard, 8 Ordnance — see Artillery. Organization of engineer troops, 7, 8 Organized land forces of United States, 5, 8 Orientation, 117 Oscillations of suspension bridges, 54 Outposts, 74, 113, 131 Overhead cover, 81 Pack trains, 31 Palisades, 93 ParaUek, 103, 104 Parapet, 77, 85 Paved highways in relation to mili- tary operations, 63, 64 Personnel, industrial, 144, 146 Photography, 31, 127, 135 Picrates, 107 Pile bridges, 48 Pile drivers, 33, 48, 49 Pits, militarj', 93 Placarding bridges, 62 Place sketch, 118 Plane table, military, 116 Plans rarelj' used in military' engi- neering, 22 Plant, construction, use of in mili- tary engineering, 21, 22, 25, 26, 32, 33 Plant — see Power plants. Plows, 32, 64, 70 Point of attack of a fortress, 102 Plattsburg camp, 155 Ponton equipage — see Bridges. Popular ideas as to military' strength, 1 Power plants, portable gasoline driven, 32, 33, 140 Portable tools, 25, 28, 29 Pratt truss, 50, 62 Preparation more necessary today than in past, 2 Prevention of disease, 138 Prices for war material, 149 Primers, 107 Principal sketcher, 126 Profile, 132, 133 Problems, tactical, 150, 159 Proportion of engineer troops with an army, 7 Purification of water, 139, 140 Purposes of military operations, 72 Qualifications, of engineer officers, 9, 10, 12, 99 Railroads, 7, 15, 26, 32, 63, 74, 109, 110, 111, 125, 142, 148 Rate of output of industrial plants, 146 Reconnaissance, 113 aerial, 74 military, 14, 76, 108, 113 Regular army, engineer troops, 8 Regular training, in Germany, 3 Repair of bridges, 60 Reproduction, map, methods and equipment, 15, 29, 31, 32, 127 Reserve, trained, 3, 5, 10, 76 Reserves for firing line, 87 Reserves of material, 29, 143 Reservoirs, 139 INDEX 185 Resources of the state, to be at dis- posal of government, 2, 3 Resources of United States, 151 Resources do not constitute strength, 1 Retaining walls, 70 Revetments, 82 Rifle trenches — see Field fortifica- tion, 74, 77, 78, 80, 81, 82 Roads, military, 15, 63, 74, 125, 131 alignment, 64, 66, 67, 68 bearing power, 66, 67, 70 brick, 66 corduroy, 66 culverts, 70 demolition of. 111 dragging, 71 drainage, 70 economics, 64, 67 grades, 67, 68 gravel, 66 location, 64, 67, 68, 69 maintenance economics, 64, 70, 71 nature of traffic, 63, 64, 65, 67 plant, 64, 65 speed of transport, 65, 66 surfaces, 66, 67 switch backs, 70 widths, 67 Rockets, signalling, 96 Saddle, ponton, 37 Safe loads of bridges, 37, 38, 40, 60 Samples of war material, 145 Sandbags, 80 Sanitary functions of engineers, 136, 141 Sanitation, 14, 15, 136 Scales of maps, 115 Scrapers, 32, 64, 70 Searchlights, 94, 96 Searchlights, power for, 96 Security, false sense of in United States, 1 Service, citizen's obligation of, 2, 3, 163 Selection of camp sites, 133 Septic tanks, 140 ' Sewage disposal, 137, 138, 140 Sextant, 118 Shear and chord increments, 62 Shell, high explosive, 74, 78, 84, 106, 112 Shelters, bomb- and splinter-proof, 74, 84 Shiraose, 107 Shortage of supplies, effect on mili- tary, operations, 150, 151 Shrapnel, 74, 80 Siege operations, 75, 100 Siege works, assault of, 100, 104 Signal corps, 16 Simplicity in military engineering, 21, 28, 33, 74, 97 Site, selection of for bridge, 47 . Sketches, area and road — amount covered in one day, 126 Sketches, military landscape, 134, 135 Sketching, military — see Maps, 113 Sketching, combined, 126 Sky line or crest, 85 Slopes, measurement of, 118, 119 Sorties, 102 Sources of supply, record of, 143 Spans of bridges — see Bridges. Spar bridges, 50, 51 Specialists, civilian — see Civilian spe- cialists. Specialization in military engineer- ing, 15, 16, 17 Specifications for material, 145 186 INDEX Speed in military engineering con- struction, 13, 18, 19, 20, 21, 22, 23, 24 Sprengel safety mixtures, 107 Stimulative measures for produc-: tion of munitions, 143, 145 Strategical fortification, 72, 100 Strateg>^ 73, 136 Stream crossings — see Bridges, fords, and ferries, 36 Strength of existing liridges, formulae, 60, 61, 62 Stringers, bridge — see Balk, 37, 47, 56, 60, 61, 62 Stumps, removal, 69 Subteiranean attack — see Mining, 89 Successive pontons, 40, 41, 43 Superintendence on works of mili- tary engineering, 23, 74 Supplies required by an army, 142 Supports for firing line, 74, 76, 86 Surveying instruments — see Instru- ments. Surveying — see Maps, for road location, 69 Suspension bridges, 62 Switch-backs, 70 Tactical requirements in military engineering, 10, 17, 19, 34, 73, 98 Tamping of explosives, 108 Taylor, Gen. Zachary, quoted, 35 Telegraph lines, 74, 108, 109, 125, 131 Telephone lines, 32, 74, 108, 109, 125 Terrain exercises, 158 Time controlling element in military engineering, 18, 19, 23, 26, 64 Time required for training of officers, 9, 10 Tools, machines and gauges in manufacture, 145 Tools — see Equipment, 23, 24, 25 commercial types, 28, 29 intrenching (portable), 25, 27, 28, 29 railroad, 32 special types, 29 Towers, suspension bridge, 53 Traffic: effect of grades, 67 military, nature of, 64, ^5 Training, military: in Germany, 3 in Great Britain, 5 Training of civilian volunteer engi- neers, 10, 11, 17, 163 Transit, 69 Transportation, 3, 14, 142, 148 Traverses, 84 Trees, 69, 85, 92, 93, 99, 100, 112, 127, 132 Trenches — see Field fortification : communicating, 74, 88 rifle, 74, 77, 78, 80, 81, 82 support, 74 Trenching machines, 32, 33 Trestle bridges, 47, 48, 56 portable, 37, 43 Trinitrotoluol, 107 Truss bridges, 49, 50, 56 Tunneling — see Mining Typhoid fever, 138, 139 Type plans for field fortification, 97 Undulations of suspension bridRos, 54 Universal training, in Germany, 3 Ventilation : bomb-proofs, 88 camp sites, 138 mine galleries, 92 roads, 69 INDEX 187 Vertical intervals, 119, 121 Visibility of points and areas, 132, 133 Volunteer army required in case of war, 6, 7 Volunteer engineers : commissions in, 160 training of, 10, 11, 17 Volunteers, dependence of United States on, 5 Von Moltke, 3 Vulnerable points selected for demo- litions, 109, 110 Wagons, tool, 31 Wanton destruction, not justifiable, 106 War the field of the expert, 2 War, cost of, 18 Wars of the United States, unneces- sary cost of, 1 Water-borne diseases, 139 Water supply — see Camps, 125, 131, 137 Weapons determine characteristics of fortification, 74, 75 Weights, of ponton equipage, 37, 40 Wells, 139 Widths: of bridges, 56 of roads, 67 Winches, portable, 33 Women, employment of, in indus- try, 146 THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO 50 CENTS ON THE FOURTH DAY AND TO $100 ON THE SEVENTH DAY OVERDUE. m 17 10 ^^ JUL16 1W& OCT 29 1937 OCT 31 1938 AUG 21 1942 gSeV .itfit^* 38 9Npv'51LL LD 21-50m-l,'33 J'fCt VB 04337 3y^//^ 13? ' THE UNIVERSITY OF CALIFORNIA UBRARY /