"Ordinarily infantry intrenches itself whenever it is compelled to halt for a considerable time in the presence of the enemy." (Infantry Drill Regulations.) Trenches are constructed with a view of giving cover which will diminish losses, but they must not be so built or placed as to interfere with the free use of the rifle. A good field of fire is the first consideration. The construction of a trench is simple, but the location of it is difficult. If possible, trenches are laid out in company lengths.
Intrenchments usually take the following form:
(1) Hasty Cover. Constructed by troops with the tools they carry on their person. It is a shallow trench with a parapet at least three feet thick and one foot high. It furnishes cover against rifle fire, but scarcely any against shrapnel.
(2) Fire Trench. It should be deep and narrow with the parapet flat and concealed. While in it, the troops fire at the enemy; hence the name fire trench.
Usual forms of fire trenches are as shown in the following illustration:
(3) Support Trenches. The supports sleep and live in these trenches; hence they are covered. The cover (roof) must be thick enough to afford protection from high angle artillery fire. It is placed as near the fire trench as possible.
(4) Approach Trenches. These connect fire trenches with the support trenches and the support trenches with any trenches in rear where natural covered communication is impracticable.
