defenders. A parapet thus commanded must either be abandoned or defiladed by the erection of a mound or traverse of sufficient height and solidity to protect the battery on the exposed side.

We have spoken as yet of a work simply intended to repel the attack of an enemy advancing in a given direction; but it is evident that a large army occupying an extensive field of ope ́rations would require many such works as that described, and must expect to be attacked on more points than one. Every one has heard how the Duke of Wellington was enabled to keep his army within the lines of Torres Vedras, having the sea in his rear, from which he obtained his supplies, and to defy all the efforts made by a superior force not equally well-supplied, to dislodge him.

By these "lines" we are not to suppose that his works consisted of one continuous trench and parapet flanked at intervals by bastions, but of a great number of detached works, some advanced much in front of the others, and all varying in their structure to suit the inequalities of the country and the importance of the position.

It is usual to divide field-works into three classes: first, openworks are those which have neither parapet nor trench in the rear; secondly, works which are enclosed all round; and thirdly, lines, properly so called. Of open works the simplest is a redan, or flêche, and is composed of two faces, each from thirty to forty yards long, forming an angle, the apex of which projects towards the enemy. The open part of this and of similar works is called the gorge. Fig. 1 represents a redan, one of the sides of which has a flanking shoulder. Sometimes two redans are united, and form what is termed a double redan (Fig. 2). This form of work Fig. 2.

Fig. 1.

possesses the great advantage over the single redan, that the adjacent faces flank each other. Open gorged works are mostly constructed much in advance of the main works, and it is desirable that they should be commanded by the fire from other works in the rear, in order that, if taken by the enemy, they may be of no use to him.

To the second class belong redoubts, star-forts, and bastion-forts. A redoubt (Fig. 3) is a rectangular work enclosed on all sides, with

At a short distance from usual to erect a traverse,

the exception of a narrow opening or doorway at the rear, which may be defended by a drawbridge. this opening, and inside the fort, it is of sufficient mass and height to protect the soldiers standing at the parapet in front, in case the enemy should attack it in the rear. It should here be observed, that any projecting angle, or angle

Fig. 4.

A

which includes a part of the work, is termed a salient angle. A star fort (Fig. 4) is an enclosed work of six or eight salient angles and the same number of re-entering angles.

A bastioned fort (Fig. 5) contains four salient angles and as many doubly-flanked curtains. In demibastioned forts the sides are flanked only from one extremity.

Fig. 5.

Lines (Fig. 6) are composed of a succession of redans and bastions united by curtains, and are variously named according to the description of work employed.

Fig. 6.

A tête-du-pont, or bridge-head (Fig. 7), is a work composed of a series of redans properly flanked, and is usually constructed for the purpose of enabling a retiring army to cross a river in order, and to check an enemy pressing upon it.

Fig. 7.

Ordinarily, the salient angle of a work is its weakest part, because an enemy may advance upon it without receiving any direct fire.

Unless, therefore, its face be well flanked by artillery from some

other part of the work, it is usual to cut off the point of the angle, and to mount a gun in such a way that it may be fired over the parapet, as is shown in Fig. 3.

Point-blanc fire is that which is directed at right angles to a

work.

Enfilade fire is that which is delivered parallel to the parapet, or nearly so.

Slant fire is between point-blanc and enfilade fire.

Reverse fire is when the enemy brings his guns to bear over the parapet in the rear, so as to harass the defenders of the parapet, or batteries in the front.

The peculiarity of the position of the allied armies in the Crimea is this; that they have found it necessary to entrench themselves in field-works, such as we have described, south of Sebastopol, in order to defend themselves from a hostile army in the field, and at the same time to prosecute the siege of a stronglyfortified town. Their batteries, therefore, are directed, not simply against works of a like construction to their own, but against fortifications raised at leisure and composed of the strongest materials.

It is not our intention here to describe with minuteness the various parts of a permanent fortification. Suffice it to say, generally, that a fortification is defended on all sides by trenches and parapets. constructed on a large scale and out of the most durable materials, and that it is further strengthened by detached works analogous to those already described, and by outworks of prodigious strength, all carefully flanked and placed in such a position that any attempt to approach with a hostile intention within range of the guns must be attended with the destruction of the assailant. It is said, however, to be a maxim of war that any place, however strongly fortified, must yield in time to the attack of a superior force. But to insure this success it is necessary, first, that the place should be thoroughly invested; and secondly, that there should be no other hostile force in the neighbourhood sufficiently strong to interfere with the operations of the besieging party. Both these requisites, unfortunately, are wanting in the case of Sebastopol. On the sea side, indeed, it is blockaded by the fleet, and on the south side by the allied armies; but the north side is left open, so that supplies of provisions for the maintenance of the garrison, and reinforcements of troops to replace the killed and wounded, can be admitted at pleasure.

The regular operations of a siege have, nevertheless, been con

ducted on the south side according to the usual system, though interrupted at intervals by attacks from without, and thwarted from within by the unlimited resources of men and stores-Sebastopol being not merely a strongly-fortified garrison, but the arsenal and concentrated storehouse of southern Russia. The ordinary method of conducting a siege we shall now proceed to describe.

The first operation is to establish a force able to cope with the garrison of the town to be attacked, at the distance of six or seven hundred yards from its ramparts. This is effected by approaching the place secretly in the night, part carrying intrenching tools and the remainder armed. The former dig a trench parallel to the fortification to be attacked, and with the earth that comes out of the trench raise a bank on the side next to the enemy, whilst those with arms remain formed, in a recumbent posture, in readiness to protect those at work should the garrison sally out. During the night this trench and bank are made of sufficient depth and extent to cover from the missiles of the place the number of men requisite to cope with the garrison, and the besiegers remain in the trench during the following day in spite of the fire or sorties of the besieged. This trench is afterwards progressively widened and deepened, and the bank of earth raised till it forms a covered road called a parallel, encircling that part of the fortification to be attacked; and along this road guns, waggons, and men securely and conveniently move, equally sheltered from the view and the artillery of the garrison. Batteries of guns and mortars are then constructed on the side of the road next the garrison, in such positions as are considered best adapted for silencing the batteries of the defenders. Zig-zag roads of similar structure are thrown forward in the direction of the fortress, the besiegers still taking care to keep themselves protected by their parapet, which, as they advance, is raised alternately on their right side and on their left so as to be always between them and the enemy. A second parallel is then formed, from which other approaches are thrown forward, and a third parallel is established. Meanwhile, batteries have been employed in destroying a portion of the wall, and towards this point the covered way is directed, so that the troops can march from the first parallel to the breach without once coming under the enemy's fire. The besiegers having thus reached the breach in the walls, assault it in strong columns, and, being assisted by a fire of artillery and musketry directed on the garrison from portions of the road only a few yards from the breach, are tolerably certain of effecting a lodgment. The first breach being carried, should