Intrenching is resorted to only when necessary. Troops who have intrenched themselves under fire are moved forward again with difficulty.
[462.] Supports and reserves occupying intrenchments vacated by the firing line should improve them, but they must not be held back or diverted from their true missions on this account.
[463.] Paragraphs [309] to 317, inclusive, deal more in detail with the conduct of the fire attack.
THE CHARGE.
[464.] Fire superiority beats down the enemy's fire, destroys his resistance and morale, and enables the attacking troops to close on him, but an actual or threatened occupation of his position is needed to drive him out and defeat him.
The psychological moment for the charge can not be determined far in advance. The tactical instinct of the responsible officer must decide.
[465.] The defenders, if subjugated by the fire attack, will frequently leave before the charge begins. On the other hand, it may be necessary to carry the fire attack close to the position and follow it up with a short dash and a bayonet combat. Hence the distance over which the charge may be made will vary between wide limits. It may be from 25 to 400 yards.
The charge should be made at the earliest moment that promises success; otherwise the full advantage of victory will be lost.
[466.] The commander of the attacking line should indicate his approval, or give the order, before the charge is made. Subordinate commanders, usually battalion commanders, whose troops are ready to charge signal that fact to the commander. It may be necessary for them to wait until other battalions or other parts of the line are ready or until the necessary reserves arrive.
At the signal for the charge the firing line and nearby supports and reserves rush forward. See paragraphs [318] and [319].