=107.= =Defence during the Bombardment and Assault.=--The amount of ammunition which can be profitably expended by the defence during the bombardment must be determined by the quantity on hand and the advisability of exposing by their fire the positions of the guns. The infantry troops and the light guns are held under cover, ready to be moved forward to meet the assault if made. Special care will be taken to avoid being deceived by false attacks; and the assault, if made, will be met as previously described (par. 6). If the attack is repulsed, an offensive return may be made by the general reserve, assisted, when necessary, by the local reserves of the front of attack; but the garrisons of the permanent works should not be withdrawn from them for this purpose, as it is always possible that they may be needed to protect the works and cover a retreat. If the assault succeeds, the defenders will retire to their positions in rear, from which the strongest possible fire will be directed upon the pursuing troops and upon the captured position to render its possession difficult or impossible. If the assailants are driven off, the position is immediately reoccupied by the defence. =108.= =Defence during the Second Period of the Siege.=--The point of attack having been definitely determined by the preliminary steps of the attack in opening the parallels and establishing the batteries, the besieged will at once proceed to mount extra guns and reinforce the troops upon the threatened fronts. He will keep his outposts or sentinels during this and the subsequent periods as far to the front as possible, to prevent surprises and to keep out reconnoitring parties spies, etc., etc. From observations previously established, he will locate at the earliest possible moment the batteries, etc., of the attack, and will prevent their completion and arming by the use of shells and case-shot charged with high explosives, fired from howitzers and mortars. He will use his long guns for counter-battering those of the besieger, and generally for direct fire upon exposed targets. By taking the initiative he may frequently obtain the upper hand in the artillery duel, and possibly be able to prepare the way for strong sorties, and the destruction of the besieger’s works. In any case he must at this stage develop the full fire of his guns and work them to their maximum value. If, however, the superiority of the artillery of the attack is pronounced, and it becomes impracticable to serve any battery advantageously, it will be better to dismount its guns and remount them in other positions, as indicated in the preceding paragraph (par. 106). All efforts will be made to prevent the construction of the parallels and approaches, their positions being discovered by the use of the search and other lights, and the work upon them retarded by direct and curved fire. For the latter light rifled mortars promise to be very effective.[7]