The ground over which the enemy must pass, should he attack.
Our own front line trenches in case the enemy penetrates into them.
To achieve these objects guns may be placed:—
In a salient.
At the base of a re-entrant.
At the horns of a re-entrant.
At a bend in the trench.
In an emplacement jutting out from the general line of the trench.
In all cases the gun should, if possible, be covered from fire from the front, and should be able to sweep the front of the entrenched line with cross fire.
Thus, although each gun may be firing to its flank, its front is swept by the fire of a neighbouring gun.