d in each. Within these battle
districts, as well as in smaller forces acting alone, parts of the
line temporarily of less importance may be held weakly, in order to
economize troops and to have more at the decisive point.

439. The front that a unit may occupy when deployed depends also upon
whether its flanks are secured. If both flanks are secured by other
troops, the unit may increase its front materially by reducing its
reserve or supports. If only one flank is so secured, the front may
still be somewhat increased, but the exposed flank must be guarded by
posting the supports or reserve toward that flank.

Natural obstacles that secure the flanks have practically the same
effect upon deployment.

440. Except when assigned as supports or reserve, regiments in the
brigade, battalions in the regiment, and companies in the battalion
are, when practicable, deployed side by side.

441. In the deployment, battalions establish the firing line, each
furnishing its own support.

In each unit larger than the battalion a reserve is held out, its
strength depending upon circumstances. In general, the reserve is
employed by the commander to meet or improve conditions brought about
by the action of the firing line. It must not be too weak or too split
up. It must be posted where the commander believes it will be needed
for decisive action, or where he desires to bring about such action.
When necessary, parts of it reenforce or prolong the firing line.

ATTACK.

442. An attack is bound to succeed if fire superiority is gained and
properly used.

To gain this superiority generally requires that the attack employ
more rifles than the defense; this in turn means a longer line, as
both sides will probably hold a strong firing line.

443. With large forces, a direct frontal attack gives the attacker
little opportunity to bring more rifles to bear. However, if the enemy
is unduly extended, a frontal attack may give very decisive results.

444. Owing to the difficulty of control and the danger of the parts
being defeated in detail, wide turning movements are seldom allowable
except in large forces.

445. If the attack can be so directed that, while the front is
covered, another fraction of the command strikes a flank more or less
obliquely (an enveloping attack) the advantages gained are a longer
line and more rifles in action; also a converging fire opposed to the
enemy's diverging fire.

446. An envelopment of b