A military dictionary

by William Duane

When a position is taken upon a steep rock, or eminence extremely difficult of access, the lines which surround it do not absolutely require ditches for their safety, as the parapet and banquette may probably be sufficient; but if any vulnerable or weak part be observed, every effort should be used to get at a spring, and to fill up an excavation in front of it, to prevent surprises. An able engineer will be particularly careful in drawing his plan of communication, to ascertain the exact points whereby they may be protected by an enfilade from one fort to another; so that if the enemy should make a lodgment any where, he will not be able to maintain his position on account of his being flanked by other works.

Field works, or small forts are generally constructed in places the preservation of which is judged to be indispensibly necessary. Such, for instance, are necks of land that stretch into a marsh, and are surrounded by it; the passage of a road, têtes de ponts, or heads of bridges, and other objects of similar importance in offensive, or defensive operations. On these occasions the shape and size of the construction must depend upon the nature of the ground, the importance of the undertaking, and on the number of men by which the works are to be garrisoned.

Many forts in field fortification are built in triangular forms; some are square, some starred, or en étoile, some as redoubts, in the shape of demi-lunes, others in crown, or horn-work, and others again in the figures of tenailles or queues d’hirondelle.

When the object of defence is a windmill, a castle, or a small dwelling-house, the first step to be taken, is to select a spot of ground upon which you are to build the field work, so as to check and prevent the enemy’s approaches. In order to do this effectually, the shape and adjacent parts of the building must be closely attended to, and the work be thrown up without exposing it to a rear attack; but if the place to be defended stand alone, and be not supported by any ditch or eminence on its flanks, or in its rear, you must then fortify it all round. The earth which is dug out of the ditch will serve to raise the rampart, or parapet. Saliant angles, distributed at equal distances, in the shape of bastions, must be erected with good flanks to protect and cover the intrenchment. If, on account of the ground, the work should not be much raised, the parapet must be raised, in order to prevent the enemy from attempting an easy assault.

An engineer from Piedmont, who has proposed some new methods in field fortification, is decidedly against stone and masonry, in the construction of parapets and field works. His reason is self-evident; for as he justly observes, the scattered pieces which must naturally be thrown about in all directions by the demolishing of the walls in the discharge of heavy cannon, would do more mischief than the cannon itself.

It is frequently found necessary to fortify a bridge; the means adopted for this purpose must depend entirely upon the size and current of the river. If the stream should be broad and navigable, and so far from the fortress, that it cannot be defended by the ordinance of the town or fortified place, in that case a large retrenchment, resembling a place of arms, must be constructed, with strong bastions to support and cover it, curtains and half-moons, a broad and deep ditch, and covert-way that must be well secured by palisades. This retrenchment, or place of arms, must be made sufficiently capacious to hold a garrison that would be capable of opposing the attack of a large detachment from the main army of an enemy. A half-moon must be constructed within the lines, with a ditch in front, to serve as a work behind which the garrison might retreat with its artillery, disputing every inch of ground, and by that means affording sufficient time to cut down the bridge.

If the river should be narrow, yet wide enough to prevent any sudden irruption into the country beyond it, the bridges that are across must be fortified by works made of earth, which are to be covered by ditches dug in front. Half-moons, tenailles, crown and horn-works, and similar constructions, provided they be well fenced with palisades, will answer all the purposes required in such cases. The engineer, by the first glance of his eye, will be able to ascertain the situation of the country, and to fit his plans accordingly. Small lodgments, or wooden recesses, must be made as guard-houses, in which detached parties of men should be stationed to meet the first attacks of the enemy, and to keep him in check while the whole army passes over the river, or is drawn up in order of battle to dispute the passage. These intrenchments must invariably be well furnished with light artillery, for the purpose of annoying the approaching enemy. But the disposition and arrangement of these pieces must always be such as to admit of their being instantly removed, when the intrenchments are carried, under the cover of heavier ordnance which is kept playing upon the enemy from the opposite side of the river.

Practical Maxims in building Field Works. 1st. The spot on which works are to be constructed should determine their figure; nor should any attention be paid to preserve a regular form which does not occupy the ground to advantage.

2d. Every line must be so disposed, that the slope of hills all around even to the very bottom, be open to the small arms of the garrison; and every part should be discoverable to the distance of at least 500 paces.

3d. Works thrown up for the defence of a defile, should always be within musquet shot of it, which must not be more than 200 yards.