Part 4

As a C. T. leaving a fire-trench gets farther away, the width should be as soon as possible such as will allow two men to pass one another fully equipped without jostling or scraping the sides of the trench, or approximately 4 ft. at the bottom. This width with recesses described later allows rapid transit for troops passing each other in quiet parties and allowing a much greater safety in an emergency when there is no down traffic.

The front is always referred to as “up.”

Another advantage to be gained in the width of the C. T. is in the fact that it is much easier to keep dry and usable. It permits laying of regulation floor boards, allowing enough room on each side of them for the purpose of drainage, and is a means of preventing falling soil from covering the floor boards. Water will not drain off or through soil which is continually trampled on and has become sodden or irregular, and unless the floor boards are kept free from soil, they soon become useless, crooked and immovable. The width of these trenches allows the wind and sun to reach the bottom of the trench, thus helping a great deal in keeping it dry. There is no such thing as a communication trench 18 inches wide at the bottom and 24 inches wide at the top; diggings of these dimensions are nothing more than drains which in an emergency only are struggled through when passing in the open is still more impossible, and they should not be given any consideration whatever as a C. T.

The features required in a communication trench, regardless of the claims of rapid transit and only considering protection, are:

(First) Frequent traverses or turnings to avoid the effect of enfilade fire, to localize the effect of a bursting shell or bomb, to make difficult a hostile advance down the C. T. and to enable bomb parties to resist more easily their advance.

(Second) A trench that is sufficiently narrow will localize the effect of a bursting shell or bomb and minimize the effectiveness of hostile fire, which must have a high degree of accuracy to be effective. But the quicker over the ground the shorter the period of danger, and shell fire of any degree of accuracy will substantially narrow one of these narrower trenches, damaging the walls and causing casualties and other obstructions which will render passage impossible with either one or two results. Delay caused at a critical moment, or the occupants trying to obtain a passage up the trench in order to take any part in the fighting, would have to come out into the open sooner than necessary. The shelling of the C. T.’s usually is heavier for perfectly obvious reasons during an attack and when rapid transit through them is of the utmost importance. A narrow trench generally takes as long to dig as one of the wider type, owing to the restricted area in which to work.

(Third) If invisibility be possible, it is an excellent feature, but in nine hundred and ninety-nine cases out of a thousand it is hardly possible. An observed C. T. indicates the position and direction of supports, stores, reserves, dugouts, etc. This fault can be corrected to a certain extent by the careful use of the contours, dead ground, sunken roads, and all natural features, such as woods and hedges. Artificial cover may and does assist concealment, but sooner or later hostile aerial observation and photographs disclose the position of more easily concealed things than an excavated C. T. It is frequently the shadow at the bottom of a trench which gives its position away to aircraft, and the narrower the trench, the more prominent is the shadow. The soil, which is generally a different color from the surface soil, must be thrown up on either side as time does not allow it being carried away. Unless in a place of artificial cover through the length of the C. T., it is usually necessary to admit the impossibility of concealment and utilize time more profitably by taking protective measures.

Rapid transit to a fire-trench is of greater importance than rapid transit from a fire-trench, and the importance of protection is greater as the fire-trench and its dangers are approached. Methods of construction should be based on this idea and the arguments given above.

SKETCH OF TRENCH SYSTEM

This sketch shows a double-traffic communication trench leading (5 ft. wide) from reserves and H. Q. to a loopholed island-traverse about 30 yards behind the support line. At this island-traverse, single-traffic C. T. branches off to various sectors of the support line; the main C. T. leading on (from 3 to 4 feet wide) uninterrupted through the support line to loopholed island-traverse “E,” about 30 yards behind the firing line. At this island-traverse the main C. T. breaks off into single-traffic C. T. 3 feet wide. Each leads to various sectors of the firing line.

SECTION I. C. T. should start behind one of the fire-trench traverses and not from a fire-bay. Every yard should be contestable for approximately the first 15 to 20 yards. This can be effected, and at the same time the effect of hostile artillery and rifle fire and bombs localized, by a series of traverses 9 feet square, the trench being approximately 7 feet deep and 2 feet wide at the bottom. Cut into the rear of a few of these traverses is a narrow recess through which one of the defending bombing party may take up a position in the center of the traverse and fire, kneeling or standing, through a loophole at the advancing enemy. The recess gives him ample protection, including head cover, and is so cut that the entrance is out of alignment with the trench behind him and he will be unaffected by a bomb exploding there. At the same time he may work with, and direct, the bombers behind him who are bombing over the traverse, and if it becomes necessary, they can also take cover in the entrance to the recess. The loophole should not be placed so high that it becomes possible for the enemy to come forward under it.

The most dutiable arms for the members of the defending bombing party detailed for this traverse work are what are known as “close-contact weapons,” generally including revolvers, bombs, trench knives, and very often a bayonet carried by pushing it down in the puttee.

SECTION II. The time and claims of rapid transit will not allow the traverse system as employed in Section I to be continued, the narrow single-traffic C. T.’s, from wear and tear and shell fire, soon become wider, and as the width would allow rapid transit to friend and foe alike, it is of the utmost importance that some means be adopted to deprive the enemy of this advantage. Moreover, the enemy may have successfully advanced down on traversed C. T., say, at “C,” and our own bombers might still be fighting in another traversed C. T., say, at “D,” and their needs demand protection. This may be obtained if, before the single C. T.’s merge into the double, each of them be quite straight for approximately 15 yards, and island-traverse, “E,” be placed at the junction. In the rear of this island, “E,” is a large and substantial recess, into which one or two Lewis guns or automatic rifles can be placed, firing through loopholes and rendering hostile advance down both “C” and “D” communication trenches almost impossible. The recess in “E” must allow ample room in which to operate. Overhead cover is provided, and one rifle would require one long loophole, so that it could fire along either C. T. without more than a moment’s interruption. In the case of two rifles being available, there could be two such long loopholes, each covering both C. T.’s, one for kneeling and one for standing. The lower loophole gives the advantage of it being impossible for any of the enemy to get out of danger beneath it. The fact that the traverse is an island one, with passageway either side, would allow friends to advance round the traverse and up “D” to the support of friends still fighting there, and without obstructing the fire directed from the traverse at enemy advancing down “C.”

An island-traverse so constructed and manned should be unapproachable along either trench “C” or “D,” but precautions must be taken to prevent the enemy avoiding it by coming out into the open, as in active moments C. T.’s become as mutilated as fire trenches and the enemy may leave the C. T. before reaching the 15-yard stretch and approach the traverse from above or flank. In anticipation of this, the position “H” is selected slightly in rear and to flank of the traverse, and in this position one of the automatic rifles may take up, either originally or by retirement from “E,” and deliver the required traversing covering fire across the front of “E” and giving adequate protection to the garrison manning the island-traverse. Barbed wire is also generally placed in open ground such as this described, say, for instance, between “K” or “L” on either side of the 15-yard stretches to impede hostile exit and advance. The overhead traverse just in front of the island gives protection against bombs thrown down on C. T.

When covering fire is not required, the position “H” will form an alternative position should the island-traverse be destroyed by shell fire or taken by the enemy; but the latter will be of little use to the enemy as their progress passed it is blocked by a loophole placed at “H” and covering the trench “M” down which they must advance. It also covers a dummy trench, shown as “N,” down which there is a fair chance that the enemy would naturally go if a misleading notice were placed at the junction of “M” and “N.” The slight turn at the end, “O,” will prevent premature knowledge as to the real nature of this trench. The enemy’s progress may also be blocked for a short time by having rolls of looped wire, sometimes known as concertina wire, so placed in recesses in the side of the trench, and so arranged that when a man retiring down a trench can catch hold of the roll as he passes a recess, uncoils it as he runs, leaving it in the trench in a badly tangled mass.

SECTION III. Supporting trenches may be at any distance from 30 to 300 yards behind the firing trenches. The C. T. in this section is constructed on the same lines, or may be constructed on the same lines, as Sections I and II, into whatever proportions local conditions and practical considerations, and particularly dangerous places, may dictate. The zigzag plan shown in the sketch is generally safe to adopt, as it allows rapid transit with a certain amount of concession to the claims of protection, more so as it approaches the fire trenches. These C. T.’s generally should be a series of straight stretches, zigzagging at acute or obtuse angles, the length and angles governed by local conditions, the extent and direction from which each stretch might be enfiladed, and the gradient and distance from danger. It has been shown before that the shorter the stretches and the more acute the angle at the turn, the less is the danger from enfilade fire, but the C. T. with this advantage requires a greater length of time and labor in digging, as well as taking a great deal more time and effort to pass through it. In order to lessen these things as much as possible, it is always considered best to adopt longer stretches and more obtuse angles as soon as possible.

The excavated soil is naturally thrown up on the side facing the enemy, and thus forming a parapet. It can at times be used as an actual fire trench. The parapet should fulfill the same conditions as the parapet of a fire trench, and where necessary, overhead traverses should be placed. The more of these overhead traverses used, the longer can the straight run of trench be. When running up-hill, facing the enemy, it is clearly obvious that acute turns and short stretches are necessary, or, if it is not found advisable to use these and more time can be gained by digging the straight runs, then they should be dug deeper and a great deal of care taken in placing the overhead traverses.

Generally, the farther the C. T. from the enemy, the less necessity to take measures for stopping hostile advance down it, but it is a safe thing when time permits to loophole the traverses facing the long straight stretches either in an ordinary traverse or when time permits the building of island-traverses, especially at junctions. Such loopholes command the straight stretch in front and are reached by narrow trenches very similar to a drainage trench, as indicated at “H.” Here again, as well, the loopholes for at least one or two should be for kneeling fire.

Hostile attacks may also be hampered here by using the rolls of looped wire previously mentioned, or by frames of barbed wire placed at the side of the trench just behind the parapet, so that a man retiring down the trench can easily pull them down into the trench after him. Great care must be taken that C. T.’s running from firing line to support trenches do not obstruct the fire from the supporting trenches.

SECTION IV. Behind the support trenches the C. T. should be constructed on the traverse principle of _Section I_, so that the same defensive features existing for the support trenches as should exist for the firing line. In doing this, however, it should be kept in mind to provide rapid transit for troops behind these supporting lines. This is best done by continuing the zigzag system right through support trenches as shown. When necessary, this C. T. can be blocked.

It is always a possibility that support trenches may be lost, but not a probability. Therefore, undue weight should not be given against the convenience of adopting as soon as possible again the zigzag C. T. of _Section II_, the latter supplying all requirements of rapid transit and allowing the introduction of straight stretches in loophole traverses wherever required.

TELEPHONE LINES

It is generally found that artillery telephone lines are laid on the north and west side of a C. T.; infantry lines on the south and east. Lines are generally laid about two feet from the bottom of the trench, picketed inter-grooves being cut into the side of the trench. These lines must be given absolutely every protection possible by the infantry and by any one using the trenches. Far too much carelessness has at times existed which destroyed communication with artillery and infantry when it was of vital importance that it should be open.

Infantry in the trenches depend for immediate support upon their artillery, and if, through lack of supervision on the part of the officers in charge, these lines are destroyed or temporarily torn down by careless men not understanding their significance and importance, then that officer or officers is guilty of a very serious crime.

RECESSES

These are usually made in C. T. to allow for the passing of troops or bearers of stretchers, or parties passing up and down to the line carrying the many things that are necessary for the upkeep of that line.

It is advisable that these should always be placed in the same corresponding place in each stretch, as shown in SECTION III, just before the turn, so that men know where they are to be found. The first man of a party coming up having arrived at a turn, and seen or heard others coming down, can give necessary protection to his party, and a great deal of unnecessary and very exasperating and fatiguing movements, and sometimes retracing of steps, is avoided. It is also often the cause of a great many casualties in a trench where these recesses are not made, as parties of men coming and going very often, while struggling to get past one another with their loads, are caught by heavy shell fire.

The recesses should be about 8 feet long and at least 2 feet wide, and the soil excavated from these recesses could be used for strengthening the parapets of the C. T.’s at these turns. Generally, when time allows and energy permits, close to the firing line these recesses are made longer and deeper, oftentimes running to 12 and 18 feet long by 6 and 10 feet deep, although it is not advisable to crowd them too much. Recesses of this kind may also be heavily roofed and used as a very temporary shelter for stretcher cases, stores of bombs, ammunition, etc.

At every second or third stretch in these C. T.’s, either steps or an easy runway to the top of the trench should be made. This saves time on a great many occasions when parties coming over the top for speed and comfort find themselves stopped and have to take to the trench on short notice. It is also good when a serious obstruction occurs, and it is necessary to leave a C. T. and enter it again farther on.

NOTICE BOARDS

These boards should be fixed at every entrance and junction in a trench system, stating the name of the trench and the places to which it leads, and where there are trenches expressly for up and down traffic, these boards should state it. Some people argue that such notices assist the enemy when they get into our trenches, but the argument does not hold as it is very often the case they do not know the names used in the sectors, as they vary up and down the line, and generally they have a very good idea of the system they will find themselves in anyway, and there is a very small chance that a majority of them will be able to read them anyway.

Care must be taken that these notice boards are not used for what is known as “boiling up,” building fires, in braziers, etc., as the absence of these boards causes a tremendous amount of confusion when new troops are coming into the line. All officers must know the shortest routes from their own headquarters to those of companies on their flanks, as well as their own battalion headquarters, and every officer, N. C. O. and man must know the position of his immediate commander’s dugout, as well as his company headquarters, and every man must know the name of the trench that he is in and helping to hold, and this is not possible when these notice boards are destroyed.

TRENCH DRAINAGE

Efforts at drainage, which is the greatest trouble during the winter months to troops occupying the line, must be as systematic and thorough as possible. Tinkering is of very little use and brings no results but causes a great and tiring expenditure of labor as far as the men are concerned, with no end of work in sight. When taking over a sector of line, the drainage system must be thoroughly studied and a line of campaign mapped out and strictly adhered to. Thorough work in the initial stages will save any amount of subsequent unnecessary fatigue and labor. The system to be applied depends entirely on local conditions, but full advantage must be taken of the assistance which nature affords. Water running down hill is a marvelous fact; nevertheless it is often overlooked. Field drains and natural streams anywhere near the trench must be kept clear of obstructions. These are usually attended to by the overworked farmers in peace times, but as they do not work near a trench system, it must be looked after by the army. Neglect of the natural watercourses has been the cause of much of the difficulty of draining the trenches themselves.

During the winter months a trench is never really drained. A mixture in the trenches which is neither water nor good, sticky mud, but a beautiful liquid combination of water and dirt, which is thick enough not to run, is formed. Sometimes it becomes sufficiently like water to be pushed or assisted to run down hill with scrapers, boards, and anything else that is handy. Sometimes it becomes sufficiently heavy enough to be shoveled over the parapet or put into sand bags. In either of these cases it is only overcome by persistent labor, but when the mud is in its true clayed self it is a waste of time and labor to attempt to move it, and the only way, without a large amount of cursing, is to sit tight and pray for the sun to dry it.

When a valley or dip is close to the side of a C. T. a few narrow gullies through the side, of about 18 inches in width, should be made so that liquid mud can be swept along the trench and on through the gulley to a natural fall. These little gullies or ditches should start at a place or places where there are dips in the level of the trench and must be dug straight through the side, as it then becomes easier to keep clear and gives no obstruction to the flow of mud; but if facing the enemy, it should not be in a straight line, as it then allows rifle fire into the trenches. If no other way is possible, then overhead traverse or other means of protection should be taken at that point. Sometimes, when it is not possible to complete these gullies, they should be dug out as far as circumstances will permit and a block of soil or very large sods be put at the junction of the gulley to the trench and the liquid mud dipped out of the trench and dumped into the gulley, where it will be prevented from running into the trench again by these collections of sods. This process is very slow, but conditions frequently make it the easiest and most convenient way of ridding the trenches of some of the mud. This work can be carried on by what is sometimes known as a “trench patrol” or maintenance squad, which is generally detailed from the company in the support line and which patrols the system of trenches held by their battalion during the day. The N. C. O. in charge generally reports serious collapses to his company officer, who in turn reports it to the engineers, who immediately take steps to have it repaired.

The width of drainage gullies should not be less than 18 inches, thus allowing easy use of brushes issued. With these brushes and adequate gullies, very long stretches of trench can be kept in excellent condition when the trench is wide enough to allow the drying effect of wind and sun to reach the bottom. The time spent in making these gullies is saved over and over again. If there be no natural valley or dip, a sump-pit is generally dug, the size depending on the energy of the troops digging it, but generally it is about 10 feet below the level of the trench it drains, and anything from 8 feet on in diameter. It is dug some fair distance from the trenches and in a position that will allow the maximum amount of gullies to be led to it from that particular section of the trench.

After having this system worked out, the next thing is to ascertain what parts of the rest of the trench system will not be affected by this drainage, and there to dig similar sump-pits just to the side of the trenches drained, small gullies leading to them. These need only be about 6 feet deep below the trench level and 4 feet in diameter. A short gulley, 12 to 15 inches wide and 2 feet long, should lead from the trench to the sump-pit, as shown in sketch of trench system.

Sometimes the sump-pit may be semi-circular and cut into the side of the trench, but in this case some barrier must be put across it to prevent men falling in while traveling at night. The former system is far more satisfactory, and especially so when the trench is hardly wide enough to allow the passing of traffic without touching the sides of the trench.

Entrances to these sump-pits must always be kept clear of all obstructions. Very often a ridge of mud from a man’s foot-mark is enough to put a sump-pit out of action. They should be continually emptied by pumping the contents over the parapet, or carrying in pails to the nearest gulley.

The side sump-pits must never be cut under the wall of a trench. On very short notice the roof will take the place of the excavated soil and there will be no sump-pit.