The narrow beaten zone enables them to fire safely over the heads of advancing infantry from all ranges beyond 800 yards, provided the infantry are at least 200 yards from the enemy fired at. A study of the table of trajectory in the Appendix to Manual of Military Training will enable the machine gunner to decide the circumstances under which the fire is safe in each case.
Positions on the flanks and if possible to the front of the advancing infantry will render covering fire most effective, but these positions will rarely be possible. The first consideration is the concealment of the gun from the enemy's artillery, which can easily silence them if exposed. It is also necessary that the positions selected should be sufficiently commanding to enable the battery commander to see the attacking infantry during the whole advance, so as to fire only when they are moving, while at the same time he must be able to see the position of the enemy's trenches and thus direct the fire on any part desired.
INDIRECT FIRE
The best method of using covering fire in the early stages of the attack is by indirect fire from the reverse slopes of a hill or from behind a ridge or other feature. This is not difficult to carry out and in no way lessens the accuracy of the fire or endangers the troops in front, as the
