[481.] Few modifications enter into the problem of attacking fortifications. Such as are to be considered relate chiefly to the greater time and labor of advancing, the more frequent use of darkness and the use of hand grenades to augment the fire.
[482.] If the enemy is strongly fortified and time permits, it may be advisable to wait and approach the charging point under cover of darkness. The necessary reconnaissance and arrangements should be made before dark. If the charge is not to be made at once, the troops intrench the advanced position, using sand bags if necessary. Before daylight the foreground should be cleared of obstacles.
[483.] If the distance is short and other conditions are favorable, the charge may be made without fire preparation. If made, it should be launched with spirit and suddenness at the break of day. (See [Night Operations].)
[484.] In siege operations troops are usually advanced to the charging point by sapping. This method, however, presupposes that an early victory is not necessary or that it is clearly inadvisable to attempt more direct methods.
HOLDING ATTACK.
[485.] The holding attack must be vigorous enough to hold the enemy in position and must present a front strong enough to conceal the secondary nature of the attack.
The holding attack need have comparatively little strength in rear, but conceals the fact by a firing line not distinguishable from that of a decisive attack.
[486.] Supports and reserves are kept at short distances. Their strength is less if the object is merely to hold the enemy fast than if the object is, in addition, to compel him to use up reserves.
[487.] Holding attacks which may later develop into decisive attacks should be correspondingly strong in rear.
[488.] All feint attacks should employ dense firing lines. Their weakness is in rear and is concealed.