The various terrepleins may have the following amount of slope to the rear, to facilitate drainage : Interior of do., (rise towards the salient,). 0 6" 0 6" 0 6" 2'6" 0 6" on the adjoining batteries seem ready to sweep the ground which he traverses. Still moving forward, he rolls over drawbridges whose planks clatter under the feet of his horses, and through vaulted arches, which resound to the eternal smack of his driver's whip."-Paul's Letters, II. "OSSIBVS ET MEMORIA PETRI NAVARRI CANTABRI SOLERTI IN EXPVGNANDIS VRBIRY'S CHAPTER IX. MODE OF ATTACKING A FORTRESS. "Others to a city strong Lay siege encamped; by battery, scale, and mine With dart and javelin, stones and sulphurous fire; 1. BEFORE proceeding to describe modern improvements on the system of Vauban, it is desirable to explain briefly the * Inscription on the tomb of Peter Navarre at Naples, from the Monumenta Illustrium Virorum et Elogia-Trajecti ad Rhenum, 1671. mode of attacking a fortress, in order that it may be seen where improvement in the defence is wanted. The first step of the besieger is to invest the fortress; that is, to post troops on every side of it, so as to preclude the garrison from communication with the exterior, and to debar them from all aid in men, food, or ammunition. The investing army will strengthen their position by field-works, &c., as in any other case, according to the judgment of the general; and if the hostile power has an army in the field so strong as to be formidable to the investment, it will be necessary to have a sufficient force to watch and check them, called an army of observation. Fortresses are not kept, even during war, constantly garrisoned to the extent which a siege demands, as it is of importance to retain the services of the troops in the field, until there shall be a probability of attack. Strong places, too, which have been made depôts of food and ammunition for the supply of an army, may at many periods of a war be almost drained of their stores. Hence, it may be of the greatest consequence to effect the investment by surprise, if possible. Thus Tournay, one of the strongest fortresses in Europe, with its works in the best state, and all its magazines of ammunition filled, was, by the masterly manœuvres of Marlborough and Eugene, invested and laid siege to (1709) when the garrison was not half equal to its defence, when half the officers were absent, and even this scanty proportion of troops was ill supplied with ammunition. A rapid movement of corps to commence investment should, however, be made in such strength as to insure superiority in any action with the garrison. "When Lord Wellington reconnoitred Badajos in 1811, his escort, consisting of a strong body of light troops and some cavalry, forded the Guadiana, and arrived unexpectedly in front of the town, whilst the sappers, with the carts and waggons of the garrison, attended by an escort of two or three battalions, were two leagues from the place felling wood, and they were, consequently, cut off from all possibility of returning into Badajos, had the circumstance been known. As it was, they arrived so near the defences before any arrangement could be made for attacking them, that the garrison sent out additional troops to cover the entry of the convoy, which, thus supported, forced through the British, occasioning them a considerable loss."* The advantages on the side of the garrison in the contest which is about to ensue, are in greater or less degree those which we have laid down as the characteristics of fortification, (p. 2.) Those on the side of the besiegers are superior numbers, and his position on the circumference of a circle, of which the besieged occupy the middle, enabling him to choose and multiply the points of attack, to concentrate his fire, and probably to enfilade the lines of the fortress. Were he, trusting to his superior numbers, to advance at once and openly to storm the works, he would give the besieged the full benefit of their advantages, exposing his men without protection to the fire of troops covered by parapets, facing all the difficulties of lofty walls to be descended and scaled under a carefully arranged system of overwhelming flank fire, or of planting his guns, to breach these walls, on sites which the forethought of the engineer has taken care completely to command by artillery on the vantage-ground of the rampart. Where, as has often happened, there has been little science expended on the works of defence, proportionably little will be required in the attack. Where outworks are wanting, flanks distant and imperfect, counterscarps low or absent, and escarps visible nearly to their foot from a distance, it may be sufficient to throw up a battery out of musket-shot from the ramparts, breach the place, and storm it. But the besieger must act differently where his attack is directed, as we must suppose, against defences scientifically arranged. Carefully planting his batteries so as to enfilade the lines which bear upon his advance, or by a concentrated fire to silence such as he cannot enfilade, he uses the working parties which his superiority of force affords to throw up parapets for the protection of his guns, of the troops which guard them, and of their communications with the rear. As soon as the fire of his batteries has produced its effect on the defences of the place, he throws forward his working parties, casts up new * Jones's Sieges, i. 414. F cover, and erects, if necessary, new batteries to reach those works which were beyond range of the first. Still, all his guns continue to play upon the lines of the fortress, preventing the revival of their fire. As he comes within range of the musketry of the covered-way, he resorts to the aid of sapping to carry on his advances. Directing his course on the capitals of the salient angles, where he is exposed to no fire in front, he carries forward his trench or covered road by zigzags, shielded by his parapet on the right and left alternately; never exposing himself to the enfilade of the most salient outwork, and not failing to throw out fresh cover for an ample guard, whenever his approaches have advanced so far as to be beyond the reach of prompt aid from that already established. As he draws near the foot of the glacis, he plies the covered way with shells from mortars and howitzers-then saps up its salients-throws up, if necessary, lofty parapets, from which his musketry can pick off the defenders who still attempt to man the shattered salients and traverses; till, having fairly dug his way to the crest of the glacis, he strikes off trenches right and left, following its outline, until he has established a secure communication immediately overlooking the covered-way all round the front which he attacks. Here he has the escarps in view, and here he establishes his batteries to breach them, and to demolish the flanks which may still threaten to dispute his advance against the bastions. Whilst these operations are going on, a descent into the ditch is accomplished, either by sinking mines to blow in the counterscarp, or by excavating a sloping subterraneous gallery. As soon as the breach, if on an outwork, is practicable, the sap is carried across the ditch and up the fallen rubbish, and a lodgment formed on the rampart; if on the enceinte, giving access to the whole fortress, (should the garrison not capitulate), the breach is stormed, and with the success of the assault the place falls. Before entering into details of the method of modern attack, it may be interesting to furnish a brief sketch of its development. The classical manner of siege by means of great wooden towers, used as movable cavaliers, continued to be practised |