A body of infantry attacked is to oppose to the assailant its high powered weapons, machine guns, automatic rifles, rifle grenades and hand grenades and to reserve for the counter attack the grenadiers and riflemen.  There is always one line upon which the resistance must be made with the greatest energy; for its defense the following methods have been found successful.  Machine guns should be placed where they can secure the best flanking fire, and every one put out of action should immediately be replaced by an automatic rifle.  If machine gun barrage fire is to play its role successfully at the moment of assault, the guns must survive the bombardment.  Their protection is secured by placing them under shelter during the bombardment and making their emplacements as nearly invisible as possible.  They should be echeloned in depth as far as practicable.  They are generally placed in re-entrants of the firing trenches and cover the intervals between the adjoining supporting and strong points.  Where the ground will permit they are often placed in concealed positions 20 to 30 yards in front of the trenches, to break up attacks made by hostile infantry.  Not too many should be placed in the front line, and they should be echeloned in depth so as to confuse their disposition.  The value of machine guns depends on the possibility of using them suddenly for brief periods, and in using them as long as they are effective.  Machine guns disposed for flanking fire must be well covered by grenadiers; this is also true of automatic rifles.

Automatic rifles, rifle grenades and hand grenades are used to constitute a barrage to keep back the enemy.  The entire front should be defended by a barrage of hand grenades, while the barrage of automatic rifles and rifle grenades is superposed farther to the front, up to 400 yards.

All riflemen and those grenadiers not employed in forming barrages are reserved to make a counterattack.

Companies on the second line operate on similar principles; machine guns, automatic rifles and rifle grenades are arranged so as to cover every portion of the first line that might be invaded.  After a short preparation by fire from these, the grenadiers and riflemen make the counterattack.

The captains in charge of the two lines are responsible for the arrangement of the machine guns, automatic rifles and rifle grenades, the distribution of barrages and the distribution of groups for the counterattack.  The real strength of the defense consists, not in holding the fire and cover trenches, nor even the support trenches, but in holding the supporting and strong points until the counterattack can be launched.

Liaison.—­The question of liaison in battle is of the utmost importance, and complete co-ordination of the different arms is absolutely necessary.  Each battalion sends an officer or non-commissioned officer and a cyclist to the colonel, and each colonel sends a soldier to the battalion commander.