A citadel is always very useful in the event of a surprise, as the troops may collect there, and act against the enemy with more regularity, and with a greater chance of driving him back. Besides, the possession of a town commanded by a citadel is of very little use to the enemy. But should a surprise have taken place, all the troops arc to collect at the spot fixed on, from which they proceed to join on the places to be defended. As soon as the greater part of the garrison is collected, detachments are sent to the different streets to repulse the enemy, and particularly to reinforce the gates, to prevent a greater number from entering the town. The enemy may thus regularly be repulsed, and even a part of his troops be cut off.
If the garrison, however, is too weak to defend itself, it must retire to the citadel, or look out for a safe retreat. Should the inhabitants take part against the garrison, it will be necessary to set fire to the town in several places. But the greatest attention of the commander is necessary to prevent disorder, as this alone will increase the loss more than any thing, and therefore the necessary instructions are to be previously given, that every one may know his place and his proper duty in case of a surprise. In an open attack, the defenders have great advantages over the as sailants, and these being duly considered, and properly re presented to the garrison, will contribute much to increase its spirit. When such an attack is expected, great care is necessary in making the judicious arrangements, both with regard to the that ought to be defended, and the number of men requisite for that purpose. The plan of the enemy must if possible be ascertained by spies, or some other secret means. When the side of the attack is known, fire and light balls are to be thrown in that direc tion, and, when the enemy is perceived, he must be op posed with grape shot.
As soon as he arrives in the foss(-, grenades, shells, and other artificial fire-works, are to be uses. When he at tempts to mount the rampart, large trees, and other heavy bodies, are to be rolled over the parapet upon him ; and should he arrive, bayonets must be used. if he succeed in getting possession of the rampart, he must be charged by the cavalry, and reinforcements of infantry. Should these also be repulsed, the streets are to be defended, and finally the signal given for retreating to the citadel, which should be done with the greatest possible order.
The defence against a blockade, consists in having plenty of stores and provisions, and magazines where they can be safely preserved. All unnecessary persons are to he sent out of the town ; the inhabitants that remain, are to be or dered to lay in a sufficient stock of provisions, and pre miums promised for the importation of these articles. Such provisions as are in the place must be properly distributed, that they may not be consumed in an useless manner. Should provisions be scarce, the houses are searched, to know what stores the inhabitants may have, of which a part may be taken for money, if necessary. Should money be come scarce, some of it may be stamped to increase its no minal value. Copper may be coined, or loans contracted. The garrison besides should have safe habitations ; and sometimes sorties or attacks must be made, with smaller or larger parties, against the enemy, in order to annoy him, and to procure provisions. If, however, these sallies prove unsuccessful, great care is to be taken that the enemy does not penetrate into the fortress with the troops who make the sortie.
The defence of a place against an attack inform, is sub jected to greater difficulties. The first thing necessary, is to obtain a knowledge of the enemy's designs. The for tress which the enemy is most likely to besiege, may be known by the march or the quarters of his troops, by his intention to conquer a certain province, by spies, or by in formation collected in the enemy's country. The comman dants of fortresses should always advertise one another of such movements. Should a corps, with a great number of engineers or heavy artillery, arrive near a fortress, the com mandant may be assured that such a circumstance is pre paratory to a siege. In this case he immediately visits every part of the fortress, and orders all necessary repairs. The superior officers are assembled as well as the magis trates, and the commandant informs them of his intentions as far as necessary, and menaces with punishment those who may act contrary to the orders which he shall issue.
The garrison is then properly divided, that no part may have more labour to undei go than another ; and never should too large a number be ordered on duty, unless the Fortress has a very numerous garrison. A journal is to be kept, in which every circumstance that may occur during the siege is entered.