[500.] When the situation is no longer in doubt, the reserve should be held in rear of the flank which is most in danger or offers the best opportunity for counterattack. Usually the same flank best suits both purposes.
[501.] In exceptional cases, on broad fronts, it may be necessary to detach a part of the reserve to protect the opposite flank. This detachment should be the smallest consistent with its purely protective mission.
[502.] The commander assigns to subordinates the front to be occupied by them. These, in turn, subdivide the front among their next lower units in the firing line.
[503.] An extended position is so divided into sections that each has, if practicable, a field of fire naturally made distinct by the terrain.
Unfavorable and unimportant ground will ordinarily cause gaps to exist in the line.
[504.] The size of the unit occupying each section depends upon the latter's natural strength, front, and importance. If practicable, battalions should be kept intact and assigned as units to sections or parts of sections.
[505.] Where important dead space lies in front of one section, an adjoining section should be instructed to cover it with fire when necessary, or machine guns should be concealed for the like purpose.
[506.] Advanced posts, or any other form of unnecessary dispersion, should be avoided.
[507.] Unless the difficulty of moving the troops into the position be great, most of the troops of the firing line are held in rear of it until the infantry attack begins. The position itself is occupied by a small garrison only, with the necessary outguards or patrols in front.
[508.] Fire alone can not be depended upon to stop the attack. The troops must be determined to resort to the bayonet, if necessary.