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FORTIFICATION AND SIEGE OPERATIONS.
FORTIFICATION is of two kinds: Permanent Fortification-being the permanent structures erected for the defence of towns, citadels, &c.; and Field Fortification being works temporarily erected for the defence of a position in the course of a war. The present observations will be restricted to what concerns permanent fortification; and the siege operations ordinarily employed against permanently fortified places.
Before describing the system of fortification, and of siege operations in present use, it may be proper to glance briefly at the ancient system-that in vogue, with but slight modifications, from the earliest period of history down to the time of the invention of gunpowder. The defence of a town consisted, in those days, for the most part, of high walls surrounding it, with the addition of towers at the angles, for the purpose of commanding the lines of front on either side; and machicoles—a species of galleries running along the top, from which missiles could be hurled down upon the besiegers, should they approach near enough. A wide and deep moat, with a drawbridge over it, and a barbican, or fortified gateway, at the exterior end of the latter, completed the permanent main works.
The mode of attack was either by scaling the walls, or undermining them, or battering them down, wholly or in part. The first operation was attained by means of mounds of earth, called aggeres, erected near the walls, and piled up high enough to allow of a bridge being thrown across from them; or of raised stages, or galleries, moving upon wheels, called vineæ, upon which scaling parties were brought to the very crest of the fortification. Innumerable examples of such works are found in the records of ancient history; and the recent discoveries in Nineveh bring to light illustrations of them which are highly curious.
On the other hand, the defensive operations of the besieged consisted chiefly of mining, of hurling missiles from the walls at the besiegers, and of frequent sallies, for the purpose of still further disturbing them, and also of destroying their offensive mounds and moving towers-against the last of which fire was frequently employed.
The accompanying engraving, after a plate in De Maizeray's "History of Sieges," will serve to illustrate some of the most ordinary proceedings in the ancient modes of attack and defence of fortified places. On one
side is a moveable tower, or belfrey, brought up close to the wall, part of the ditch having previously been filled in for the purpose; a bridge
has been let down from the upper storey of the huge machine, over which the besiegers are rushing to storm the parapet. Below, in the ditch, are a number of archers attempting to drive the garrison from the defences; they are covered by large shields, called pavoises, each borne by a young man, called a pavoisour, A breach has been effected in the wall; the besieged are lowering a hurdle (woolsacks aud bags of horse hair were also used for the same purpose) to deaden the strokes of the ram, or fill up the chasm.
To conclude this brief sketch of an order of things long superseded but of which the pages of Homer, Josephus, Tacitus, and the Holy Scriptures themselves, contain so many illustrations, it may be observed, as a principle, that the art of defence in ancient fortification had the advantage over that of the attack; the latter requiring great numerical superiority, and unwearied labour
and patience on the part of the besiegers in effecting their approaches, as well as immense physical energy and dauntless courage in the final assault, when the besieged still fought upon equal terms with them.
CHANGES INDUCED BY THE INVENTION OF GUNPOWDER.
Though the invention of gunpowder at once effected considerable changes in military operations generally, it did not so soon lead to any material alteration in the principles of fortification. The matchlocks and small field-pieces of early construction presented no new terrors against stone walls which had long stood the test of ballista and catapulta; and, for some ages, those arms