Manual of Military Training by James A. Moss (best e book reader for android .TXT) 📖

Beginning at the front we have the line of wire entanglements or obstacles with their listening posts X, for guarding them. Connecting the listening posts to the fire trenches are the communicating trenches. The fire trenches are shown by the heavy black line running about 60 feet in rear of the obstacles. Note the many traverses shown by the indentations in the line. Points marked M with arrows projecting to the flanks are machine guns, so located as to sweep the front of the position with a cross fire. Points marked S are underground shelters for from 3 to 6 men. Points marked S' are shelters for 30 men. In rear of the firing trenches at a distance varying from 100 to 200 feet is the line of cover trenches. This line is connected with the fire trenches by the zig zagged line of communicating trenches. Note that the latrines (L) and first aid stations (F) are just off from the communicating trenches, while the larger shelter for men (S') are near the cover trenches. As the note on the diagram shows, the trench requires 250 men to occupy it with double that number in support. The trench has 108 loopholes with spaces between provided with a higher banquette so that the whole parapet may be manned for firing.

On the battlefields of Europe today there are generally three lines of fire trenches. This permits the defender to fall back to a 2nd or 3rd prepared position in case he is driven out of his first trench. On a hill we find a fire trench near the foot of the slope, one just forward of the military crest, and the third on the reverse slope of the hill.

In many instances the first line trenches consist of as many as four or five lines of trenches running in a general lateral direction and connected by deep narrow communicating trenches. The depth between the first and last of these trenches is, in some instances, not over a hundred yards. Sign boards are necessary at short intervals to prevent the soldiers from getting lost. The effect of having so many alternative firing trenches is to make it extremely difficult for an enemy to advance from, or even to hold one of them, even when he gains a footing, as he would be swept by fire from the supporting trenches in rear and also by flanking fire from the adjacent trenches.

1161. Location. There are two things to be considered in locating trenches: (1) The tactical situation, and (2) the nature of the ground. The first consideration requires that the trenches be so located as to give the best field of fire. Locating near the base of hills possesses the advantage of horizontal fire, but, as a rule, it is difficult to support trenches so located and to retreat therefrom in case of necessity. While location near the crest of hills—on the "military crest"—does not possess the advantage of horizontal fire, it is easier to support trenches so located and to retreat therefrom. Depending upon circumstances, there are times when it will be better to intrench near the base of hills and there are other times when it will be better to intrench on the "military crest," which is always in front of the natural crest. The construction of trenches along the "military crest" does not give any "dead space"—that is, any space to the front that can not be reached by the fire of the men in the trenches.

Whether we should construct our trenches on high or low ground is a matter that should always be carefully considered under the particular conditions that happen to exist at that particular time, and the matter may be summarized as follows:

The advantages of the high ground are:—

1. We can generally see better what is going on to our front and flanks; and the men have a feeling of security that they do not enjoy on low ground.

2. We can usually reënforce the firing line better and the dead and wounded can be removed more easily.

3. The line of retreat is better.

The disadvantages are:—

1. The plunging fire of a high position is not as effective as a sweeping fire of a low one.

2. It is not as easy to conceal our position.

The advantages of low ground, are:—

1. The low, sweeping fire that we get, especially when the ground in front is fairly flat and the view over the greater part of it is uninterrupted, is the most effective kind of fire.

2. As a rule it is easier to conceal trenches on low ground, especially from artillery fire.

3. If our trenches are on low ground, our artillery will be able to find good positions on the hill behind us without interfering with the infantry defense.

The disadvantages are:—

1. As a rule it will be more difficult to reënforce the firing line and to remove the dead and wounded from the trenches.

2. On a low position there will usually be an increase of dead space in our front.

3. The average soldier acting on the defensive dreads that the enemy may turn his flank, and this feeling is much more pronounced on low ground than on high ground. Should the enemy succeed in getting a footing on our flank with our trenches on top of the hill, it would be bad enough, but it would certainly be far worse if he got a footing on top of the hill, on the flank and rear, with our company on low ground in front. We, therefore, see there are things to be said for and against both high and low ground, and the most that can be said without examining a particular piece of ground is: Our natural inclination is to select high ground, but, as a rule, this choice will reduce our fire effect, and if there is a covered approach to our fire trenches and very little dead ground in front of it, with an extensive field of fire, there is no doubt the lower ground is better. However, if these conditions do not exist to a considerable degree, the moral advantage of the higher ground must be given great weight, especially in a close country.

The experience of the European war emphasizes the fact that the location of rifle trenches is today, just as much as ever, a matter of compromise to be determined by sound judgment on the part of the responsible officers. The siting of trenches so that they are not under artillery observation is a matter of great importance, but, it has yet to be proven that this requirement is more important than an extensive field of fire. There are many instances where to escape observation and fire from the artillery, trenches were located on the reverse slopes, giving only a limited field of fire. This restricted field of fire permitted the enemy to approach within a few hundred yards of the trench and robbed them of the concealment they had hoped to gain. The choice between a site in front, and one in rear of a crest, is influenced by local conditions which govern the effectiveness of our own and the enemy's fire. In general, the best location for effective fire trenches, lies between the military crest of rising ground and the lowest line from which the foreground is visible. If the position on the military crest is conspicuous, it is inadvisable.

With regard to the nature of the ground, trenches should, if practicable, be so located as to avoid stony ground, because of the difficult work entailed and of the danger of flying fragments, should the parapet be struck by an artillery projectile.

To locate the trace of the trenches, lie on the ground at intervals and select the best field of fire consistent with the requirements of the situation.

Trenches should be laid out in company lengths, if possible, and adjoining trenches should afford each other mutual support. The flanks and important gaps in the line should be protected by fire trenches echeloned in rear.

1162. Concealment of trenches. Owing to the facilities for observation that the aeroplanes and other air craft afford, and to the accuracy and effect of modern artillery fire, every possible means should be taken to conceal trenches, gun implacements, and other works. The aim should be to alter the natural surface of the ground as little as possible and to present a target of the smallest possible dimensions. Covering the parapet with brush or grass will afford temporary concealment. If the new earth can be sodded it aids greatly in concealing the trench. In some cases troops have gone to the extent of painting canvas to resemble the ground and have placed it over trenches, guns, etc. Straw and grass placed in the bottom of trenches make them less conspicuous to air scouts. When trenches are dug on a fairly steep slope care must be used to conceal the back of the trench, which, being higher than the parapet, will stand out as a scar on the hillside. Grass or brush may be used to conceal the back of the trench.

1163. Dummy trenches. May be constructed which attract the enemy's attention and draw his fire, or at least a part of it. The extent to which this method may be used may include the construction of dummy obstacles and guns, and even hats may be placed on the parapets.

1164. Length of trench. The usual minimum allowance of trench space is one yard per man, although in some tests, two feet was found sufficient for men to fire satisfactorily. Ordinarily one squad will occupy the space between two traverses which experience has shown should be about 15 feet apart.

1165. Preparation of the foreground. One of the first principles in improving the foreground is that an enemy attacking the trenches shall be continually exposed to fire especially in the last 400 or 500 yards. This requires a clearing of the foreground and a filling in of depressions or leveling of cover. Dead space may be swept by fire of trenches specially located for that purpose. Those features of the ground which obstruct the field of fire, restrict the view, or favor or the enemy's approach, should be removed as far as possible. On the other hand, features which favor the concealment of the trenches or increase the difficulty of the attack would better be left standing, especially when it is possible to fire through or over them.

1166. Revetments. By a revetment we mean a facing placed against the front or back wall of a trench to keep the earth in place.

When trenches are to be occupied for any length of time, they must be revetted. There are many forms of revetments. Sod revetments, stakes with brush behind them, stakes with planks, boards, or poles behind them and a common form seen in the trenches in Europe chicken wire with