6. Permanent works being designed to be secure against assaults and surprise, their guns of position are protected as well as circumstances admit against the hostile artillery and infantry fire. During the cannonade preliminary to an assault a wise discretion must be used as to how much ammunition may be profitably expended in replying to it, and how great an exposure of the men to the artillery fire is justifiable. As a rule but little reply is made from the work.
The machine and rapid-fire guns should be withdrawn from the parapets and be protected under bomb-proofs until the relaxation of the hostile fire due to the near approach of the assault allows them to be run out and to open fire. The infantry of the garrison is similarly handled, being held under cover until the proper moment, then manning the parapet and pouring a close, rapid, and deadly fire upon the assault.
The fire of the fronts directly attacked, both machine-gun and infantry, will be directed principally at the assaulting columns and working parties, the collateral works and fronts will, in addition to pouring a cross-fire upon the assaulting columns, direct a large part of their machine-gun fire upon the supports and reserves, while the more powerful guns will generally direct their fire upon the hostile artillery.
The troops not needed for manning the parapets are held under cover in a central position as a reserve, to strengthen the force at any part of the parapet or to meet and drive out any body of the enemy penetrating the work.
Should the attack be repulsed, the most rapid and destructive fire from all arms is directed upon the retreating troops with a view to inflicting the greatest possible losses; but a counter-attack is, as a rule, not attempted. When made, however, it should be limited to making an advance upon one or both flanks to a position giving a more effective fire upon the retreating troops, and retiring from this position to the cover of the work as soon as the main attack is completely repulsed and before the advanced troops become compromised by a close engagement with the enemy.
BOMBARDMENT.
7. By a bombardment, technically speaking, is meant a more or less continuous shell-fire upon a place with a view to destroying magazines, buildings, materials, and supplies of all kinds, in addition to inflicting the greatest possible losses upon the garrison and producing among the inhabitants a state of terror and unrest, frequently extending to mutiny, and finally causing the surrender of the place.
The term bombardment is also frequently applied to a cannonade opened upon a place to silence its artillery prior to an assault or during a siege.
A bombardment promises success when the place is small and not well provided with bomb-proofs, when the garrison is weak or of bad morale, when the inhabitants are numerous and not in sympathy with the garrison, or when the commandant is weak. A well-built and well-equipped modern fort can hardly be reduced by bombardment with any reasonable expenditure of time and ammunition; although the successful use of torpedo-shells charged with high explosives will probably render untenable works not designed to resist their effects.
When it is designed to reduce a place by bombardment a complete investment is, as a rule, necessary only to prevent the withdrawal of the non-combatants (a severe measure, but one frequently adopted), or to insure the capture of the garrison upon the fall of the place.