CHAPTER XI.

FIELD ENGINEERING.

(_See also_ “Manual of Field Engineering.”)

=238.= _Entrenching and concealing guns._

1. The importance of concealment, both in attack and defence, has increased with the destructive effect of quick firing artillery, but is valuable only so long as its employment does not interfere with effective fire.

2. There is a two-fold object in making use of cover, viz., concealment from view and protection from fire. By these means the possibility of surprising the enemy with fire is increased, while the possibility of being immobilized by hostile fire is diminished.

3. Guns may be concealed either by making use of natural or artificial cover, and sometimes by the selection of sites with a suitable background, but reconnaissance of the position can alone show if concealment is likely to be temporary or permanent. If circumstances permit, the sites for the guns should be viewed from the most suitable observation posts for the enemy’s artillery before they are finally fixed, bearing in mind that positions which are effectively hidden from the front often become visible by moving a short distance to a flank.

4. Advantage should invariably be taken of any natural cover available, but to give efficient protection against fire some artificial cover will usually be required.

When the contour of the ground is favourable trees will give valuable cover from view, and so make it more difficult for the enemy to obtain the range. A position behind a wood, a hedge or belt of trees can often be found where the guns can be brought into action unseen by the enemy, the fire being observed from a position in rear.

5. Experience shows that anything that breaks the view close in front of distant objects greatly increases the difficulty of seeing them. Such material as nets or bamboo trellis with bits of the surrounding vegetation stuck into them may be used for this purpose. If guns have to be placed on a skyline, a strip of sacking stretched in front of them may serve as a false skyline when viewed from the enemy’s position. Similarly brushwood hurdles placed behind guns to act as a background will often conceal them for the time being.

To prevent guns being located by the dust thrown up on discharge the ground should be watered for some yards in front of the muzzles, or such material as raw hides, and sacking, pegged down over it.

For a similar reason the movements of guns and individuals must be restricted as much as possible when there is any likelihood of the enemy being able to observe them.

6. In entrenching guns the first consideration is fire effect, the second that while getting some cover in the shortest possible time the form of the work should be such as to admit of gradual improvement in the event of more time being available.

The site of a gun emplacement having been selected, the first step is to decide whether an epaulment or pit is most suitable, the next is to mark out the platform for the gun, which must be large enough to enable it to be traversed so as to engage any likely objective.

In deciding whether gun pits or epaulments are to be made, it must be remembered that sinking the guns reduces their field of fire and makes more dead ground in front of them if the position is not already under cover.

On the other hand the difficulty of locating guns from aircraft is greater if sunken sites without parapets are employed.

7. At first, a simple parapet to supplement the cover afforded by the shield and to protect the detachment, when kneeling, from oblique fire should be provided. For this purpose some empty corn sacks may be carried by guns on active service. These may also be found useful in bright weather in preventing the glint from the tyres disclosing their position. Subsequently the cover can be improved and pits, with ammunition shelves or recesses in front or rear to cover the detachment standing, may be added, but a clear space of 13 feet between these pits is necessary for working field guns. The breadth of the embrasure will depend on the field of fire to be covered. The recoil of the gun carriage should be prevented by digging a trench for the spade, butting it against a plank or sleeper.

8. Every effort should be made to assimilate the emplacement with its surroundings. Sharp angles, steep ends and clearly defined embrasures, which throw dark shadows, should be avoided as likely to attract attention, and the intervals between the emplacements themselves may be filled with some form of screen with advantage.

Any newly-turned earth, if liable to be seen by the enemy, should be covered with turf, bushes, &c.

9. If time and tools permit, cover for an ammunition wagon near each gun, and a blinded communication trench for the men replenishing ammunition should be provided; or, where this is not practicable, some shelter pits to afford resting places for the men supplying ammunition by hand from the wagon line.

Where still more time is available traverses against enfilade fire and overhead splinter-proof cover may be prepared. For the latter purpose uprights are needed to carry horizontal transoms on which planks or corrugated iron are arranged to support earth to the thickness of 12 inches. Uprights and transoms should be 8 to 10 inches in diameter, except in the case of such of the latter as are only required for short spans.

Special cover is required for the battery commander and his headquarters, the battery leader and his signallers, and section commanders. A type of protected observing station is shown in Plate IV. If time admits, head cover with some form of loophole should be added.

10. Diagrams of an epaulment and gun pit are shown on Plates V and VI, but they are not intended as types to be rigidly copied on all occasions.

For heavy guns a parapet about 3 feet in height should be carried round in front of the carriage, and should be constructed with a radius admitting of ample interior space and a wide field of fire. The gun should be run as close to the parapet as possible. It is generally inadvisable, unless artificial platforms are available, to disturb the natural surface of the ground.

11. Cover from both view and fire may sometimes be obtained by a combination of natural and artificial cover:--