Annals of a Fortress

by Eugène-Emmanuel Viollet-le-Duc

With good troops, then, we might have raised in one night, works which would have enabled us to resume the offensive, and to push further on, to break the line of contravallation, and seriously to embarrass the besieger. It is not therefore proved that long ranges give a greater advantage to the attack than to the defence, while, on the other hand, the long range of rifled cannon may be affirmed to be favourable to the defence; but it would be so only on the condition of the works being planned in view of the new action of artillery, and not according to old traditions, however glorious. The destructive power of explosive projectiles puts obstacles in the way of the besieger's approaches; and, in fact, during the late war we never saw employed that old mode of approach with a view to attacking by breach and crossing the ditch.

The Germans were not so stupid as to employ these classical methods. They took up their position on favourable and often commanding points, at three thousand eight hundred to four thousand two hundred yards around our fortresses, which adhered to the old defensive system adapted to ranges of two thousand two hundred yards at most; and covered with shells our works and the towns they were supposed to protect, without risk to a single sapper. We thought that odious and unreasonable; like those nobles of the fifteenth century, who thought it an abominable shame that their feudal nests should be breached with bombards, and declared that the trade of war was thereby damaged. But suppose we should some day condescend to practical consideration, when these old flanked fronts fall into disesteem, and the new generation of military engineers determine to admit that we have to do with artillery of long range, and to take advantage of the fact, a certain degree of superiority might be doubtless given to defence over attack.

How ought these isolated forts, which are destined to replace the salients of our old fortresses, to be planned? They should afford ample space for a large number of fires—even indirect fires—in case of need; consequently extended faces and short flankings—that is, as shallow as possible, and perfectly open gorges. They should efficiently protect the works of counter-approach, and consider defence at close quarters as a question of only secondary importance; for very seldom would there be occasion for it, if indeed the case ever presented itself, which is doubtful.

Fig. 84.

Referring to the general defensive system shown in [Fig. 83], and required the plan of one of the forts, A, the result will be [Fig. 84], giving the work at the lower level at C, and at the level of the batteries at D. The counterscarp should be cased up to at least sixteen or seventeen feet above the bottom of the ditch.

The escarp should be made with tipped earth. The masonry works should all be covered and secured from being enfiladed; they form casemates inside E. Beneath the terracings, powder magazines, F, and the passages communicating with the oiseaux or lower orillons, G, protected by the counterscarp and the covered way, and which are used only if the enemy attempts to pass the ditch. The faces and flanks on the outside are planned on angles sufficiently obtuse to cross their fires. The two faces in the plan ([Fig. 84]) may be armed with eight guns and the flanks with six guns. This work is separated from that of the gorge by a traverse that efficiently protects this gorge, which possesses its flanks, armed with four guns and its orillons.

From the work of the gorge is a communication into the fort by a covered caponnière, forming traverse in the direction of the capital or centre line. The gorge is defended by a curtain for the riflemen, and, at need, for small pieces of artillery. At need also, on the terre-plein of the work of the gorge may be mounted guns of long range, affording an indirect fire in the circumference of a semi-circle, over the great traverse H, if the parapets of the faces are damaged by the fire of the enemy.

Fausse-braies consisting of palings are fixed in the ditch at ten feet from the base of the escarp, to hinder the fallen débris of the escarp from filling up the ditch, and to enable its passage to be defended. The well-covered internal masonry works prevent the accumulation of earth on the interior platforms, and afford casemates, which enable the garrison to take rest in perfect security; at any rate along the two faces and the great traverse. Blindages can be set up on the traverses of the batteries, and can be easily repaired every night, as well as the escarp of tipped earth.