Fire through gaps in the defensive line.
Command positions where the enemy may concentrate prior to the assault.
Command positions likely to be occupied by the enemy’s machine guns.
Command covered approaches on the defensive line.
Enable guns to fire on enemy’s trenches with greater effect.
Give overhead covering fire in case of an advance by our own troops.
General Notes on Trench Work.
If guns are often used, the positions from which they are fired should frequently be changed.
Thus the enemy may be deceived as to the number and position of the guns.
Emplacements should be numbered, and range cards placed in each.