A military dictionary

by William Duane

It is sometimes prudent to harrass and perplex the enemy that may be in the neighborhood of the town which you propose to attack, by perpetually driving in his out-posts, &c. and by forcing him to retire from the different avenues and commanding grounds; when the various objects, which are to facilitate the approaches of the besieging army, have been accomplished, the lieutenant-general who is entrusted with the investment of the town, must procure faithful and intelligent guides, advance by forced marches, halt as little as possible, and then only for the purpose of refreshing his men. He must studiously preserve the secret of his expedition, until he gets so near to the town, that the object of his approach becomes manifest and unequivocal.

When he arrives within one days march of the town, he must detach from his main body two or three parties of horse, (each party to be stronger than the garrison of the place) which must lie in ambush in the neighborhood, for the purpose of carrying off cattle, or of making prisoners. The instant he reaches the town, he must seize upon all the leading avenues, and draw his army up on some advantageous ground. He then goes out to reconnoitre, and to discover the most likely places by which succours might be conveyed into the town. He must have the precaution to post a strong guard in each of these places.

His next business will be to send out small scouting parties, in order to obtain correct intelligence respecting the enemy’s motions. Every outlet is blocked up by some dragoons, for the purpose of hemming in the garrison as close as possible. He makes it his study moreover to acquire personal information by examining the prisoners, with regard to the nature of the country, the different fords, rivulets, points of enfilade, avenues, strong buildings, or commanding heights in the neighborhood. He further enquires as to the strength of the garrison, and the number of officers; whether the governor suspects that a regular siege is intended: whether he expects succours, supplies of stores and ammunition, and from what quarter he is to be furnished; finally, whether the fortifications be in good repair, and the place equal to a defence.

At night he sends out advanced parties, with directions to bivouac within musquet shot of the town, and takes especial care always to post strong parties in those places and avenues by which succours and supplies might be easily conveyed to the garrison. He has likewise the precaution to have different small guards, or out-lying and in-lying piquets, both in his front and rear, to prevent surprizes. On these occasions the detachments are formed, half on foot and half mounted; those on foot constantly remaining at their horses’ heads, bridle in hand. These detachments are on the alert during the whole of the night, and only one half of the number is suffered to repose during the day.—Whenever the commanding officer has received intelligence of the approach of a body of troops to relieve the garrison, he must make his dispositions in such a manner as to give them battle, before they get sufficiently near to throw themselves into the town in scattered and divided parties. Great caution, however, must be observed under these circumstances, not to advance too far, lest it should only prove a feint on the enemy’s part, in order to induce him to weaken some of his posts; and by taking advantage of their absence, to throw some succours into the town.

As the principal, indeed the only object which the lieutenant-general can have, is to prevent any assistance being given to the garrison, whilst he invests the place, he must always be on horseback; he must incessantly visit the different posts, thoroughly reconnoitre the country, and minutely examine those quarters, through which succours or supplies might be conveyed to the garrison, or which offer advantageous positions for his own troops to occupy. During the investment of the town, it will be his duty to collect all the intelligence and information he can, respecting the state of the works and the adjacent points, in order to communicate fully with the general in chief, when he brings up the besieging army, and to put him in full possession of every thing, which may facilitate the object of his enterprize.

The chief engineers should always accompany the lieutenant-general who is entrusted with the investing of a town, in order to get the necessary knowlege of the place before hand, and to understand how the lines of circumvallation, &c. should be drawn, three or four days before the main army arrives; they should moreover make several rounds for the purpose of reconnoitring. These measures will conduce a great deal towards a wise and effectual method of investing the place. To accomplish these ends, a correct plan of the town must be procured. This plan must be reduced, and a rough sketch taken of every thing within half a league of the circumference of the town; after which a small chart may be drawn of the lines, &c. which are to be made for the purpose of carrying on the siege. This must be done in concert with the lieutenant-general who ought to know better than any body, what the order of battle will be, how much ground is to be occupied by the different brigades and regiments and what the relative detail of the whole army will require.

From the day on which a town is invested, every thing is thrown into motion. The train of artillery is directed to be brought out with necessary stores and ammunition, and proper carriages, with their drivers, are impressed; every department, in a word, performs its allotted duty, and the board of ordnance, as well as the commissary general’s office become subservient to the orders that are issued by the general in chief.

Whilst the necessary measures are adopted for the close investing of the town, the main army approaches by forced marches, and generally arrives before the place five or six days after it has been invested. The lieutenant-general, or officer commanding the investing army goes out to meet the main body when it is within half a league of the place, and communicates with the general; who, in consequence of the report he makes, gives directions respecting the lines of circumvallation, &c.

For further particulars on this article, see Traité de l’Attaque des Places par le Marechal Vauban revue, &c. F. P. Foissac Chef de brigade au corps du Génie de la Republique Francaise, vol. i. page 69.

INVESTISSEMENT. (A French word which is strictly military. The celebrated Vauban has erroneously used investiture to signify the same thing.) The act of investing any town or place in such a manner as to prevent the garrison or inhabitants from receiving succours or provisions.