he has further hazarded some questionable opinions, and indulged in abstract and delicate discussions, which are certainly out of place even in such a work, and which appear but little calculated to benefit persons possessing only a superficial acquaintance with the matters forming the subject of these disquisitions. M. de Bousnard's work, therefore, though intended to serve as an elementary treatise on fortification, is much too elaborate and refined ever to be used as such, and also too expensive for the pecuniary means of a great number of inferior officers, whose instruction the author professes to have had chiefly in view. But to teachers of fortification it is altogether indispensable; and as long as the science and practice shall continue on their present footing, it will be deservedly considered as the most comprehensive and valuable work on the attack and defence, as well as the construction, of all kinds of fortification.
With regard to Carnot's Traité de la Défense des Places Fortes, it was written to serve a temporary purpose; and the celebrity which it acquired on its first appearance has for some time been rather on the decline. The more prominent innovations recommended in this treatise were, first, an alteration in the trace or outline of the polygon; secondly, the suppression of the exterior revêtement of the covered way, known as the counterscarp; thirdly, the detachment of the scarp-wall from the rampart, and the construction of the latter without revêtement; fourthly, destructive personal conflict with the besiegers by means of frequent sorties; and, lastly, making vertical fire the basis rather than an accessory of the defence. With regard to the first of these proposals, all of which the reader will find very ably discussed in Jones's Journals of Sieges in Spain and Portugal, we have only to remark, that by means of an increased expenditure for retrenchments and casemates, as recommended by Carnot, the strength of particular portions of the polygon may be increased; and that, if he has failed in tracing a perfect front, founded on the basis of Montalembert's system of casemated and reverse fire, he has at least rescued a valuable suggestion from unmerited neglect, and rendered an important service to science by directing the attention of military men to the means most likely to create a barrier against the growing powers of the attack.
The Traité de Fortification Souterraine, suivi de quatre Mémoires sur les Mines, by M. Mouzé, lieutenant-colonel of engineers in the French service, was published at Paris in 1804, and is justly considered as the most complete work on the subject it treats of which has yet been given to the public. Subterranean fortification is a branch of the art which, until a very recent period, was wholly neglected in this country, and in which our engineers are still far behind their brethren of the continent. We learn from Colonel Jones's work on the Peninsular Sieges, that the Duke of
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1 Besides the writers above enumerated, may be mentioned the Chevalier St Julien, an able engineer, who published a method by which, he asserts, works may be constructed at a less expense, yet in such a manner as to render the defence or attack more formidable; Francisco Marchi, of Bologna, who furnished no less than a hundred and sixty different methods of constructing fortifications; Bombelle, who established three kinds of fortification, called the grand royal (grand royal), the mean royal (moyen royal), and the little royal (petit royal); Blondel, who published a system divided into two principal heads, the great and the little, whose external sides are respectively two hundred and a hundred and seventy toises; Donato Rosetti, a canon of Livorno, who wrote on the method of constructing works in what he calls fortification à rebours, or fortification in reverse, so denominated because the re-entering angle of the counterscarp being opposite to the flanked angle, it will, according to him, be necessary to attack it from the reverse side of other works; and Antonio de Herbart, major of artillery in the Duke of Wurtemburg's service, who published a treatise on fortifications with what he calls angular polygons. The treatise entitled Nouvelle Manière de Juger les Plaques tirées des méthodes du Chevalier de Ville, du Comte de Pagan, et de M. Vanbon, avec des Remarques sur l'ordre renforcé, sur les batteries du Capitaine Moréch, et sur celui de M. Blondel, which appeared in 1689, is full of strong reasoning, whence the author deduced a new system, but it contains little that is really original, though it gives numerous references to what had previously appeared, and dispenses the different parts in a judicious manner. M. de Montalembert's system of casemated and reverse fire has been in part adopted in the splendid fortress of Alessandria in Italy, constructed under the directions of Napoleon.
2 Fages-Vauvilliers, Aperçu Général et Raisonné sur la Fortification des Places. Préface, pp. xiv. xv.
3 Vol. II. p. 131, et seqq. Fortification.
Wellington's army in Spain was unattended by a single regularly-trained sapper or miner until late in the year 1813; and many valuable lives were sacrificed, from the want of these valuable, or rather indispensable auxiliaries.
Systems of Permanent Fortification.
1. Vauban's First System.
Before commencing to draw a plan of fortification, it is usual to determine upon some polygon on which to describe it. In this figure, accordingly (see Plate CCXLVI, fig. 1), we have taken the angle of an octagon, and called the length of the side 360 yards. In constructing a fortification, a figure is determined on, as near that of a regular polygon as possible, within which the enceinte or chain of main works is to be contained. The enceinte or body of the place consists of as many bastions, connected with curtains, as there are sides to the figure, and each of these is made as near 360 yards as possible, so that every part may be within range of such arms as are to be employed in its defence.
The principal or outline denotes the contour or line by which the first figure of the work is defined. This line is supposed to pass along the superior part of the cordon, and is that from which all the other parts of the work are set off.
The exterior side, or side of the polygon above mentioned as equal to 360 yards, is that upon which the front of the fortification is described, and it extends from the flanked angle of one bastion to the corresponding angle of the next, as AB. These lines are bisected, and a perpendicular, DC, is drawn from the point of bisection towards the place, its length being proportional to the extent of the exterior side and adjacent angle of the polygon; that is, one sixth for the hexagon and all figures of a greater number of sides, one seventh for the pentagon, and one eighth for the square.
The lines of defence AEG, BEH, are drawn from the extremities of the exterior sides through these points, and produced to an indefinite length; and upon the lines so drawn are set off two sevenths of the exterior sides, equal to 102½ yards, which marks out the point for the shoulder of the bastion E and F. The distance between these points is then laid along the continuation of each line of defence, and a line is drawn connecting them for the curtain GH, from the extremities of which lines are drawn to the point marked off for the shoulder of the bastion, and thus form the flanks. And in this manner is drawn a front of fortification, which being repeated round the sides of the polygon, completes the works of the enceinte or body of the place.
Vauban divided his first system into three parts; namely, the little, the mean or intermediate, and the great. The first he used for small forts of four or five sides, citadels, horn-works, and crown-works, making the exterior sides from 120 to 240 yards, the perpendicular in the square equal to one eighth, and in the pentagon one seventh, and the faces of the bastions in each equal to two sevenths of the exterior side. In the mean or intermediate, which is adapted for all sizes of towns, the exterior side varies from 250 to 360 yards, the perpendicular is one sixth, and the faces are two sevenths. In the great the exterior side varies from 360 to 520 yards. This kind was never adopted for all the sides of a place, but only when one of these happened to be near a river or a marsh; in which case the distances of the bastions should be so regulated that they may not be out of musketry range from one another.
When the curtain becomes unavoidably too long, this defect is in part remedied by erecting on it a flat bastion, which is not so high as the rest of the works.
Ground which will admit of being regularly fortified throughout is seldom or never to be met with, but, nevertheless, the rules of regular fortification must be observed as nearly as possible; that is, the flanked angles should not be less than 60°; the lines of defence should not exceed musket range, and the sides should be lengthened or shortened so as to obtain a well-proportioned front upon each. After an irregular place has been reduced to as regular a form as possible, lines are drawn parallel at the distance of about thirty yards from the houses, in order to give sufficient space for the rampart; and these lines form the interior polygon, which may be fortified inwards by setting off the demi-gorges of the bastions, and raising their flanks at an angle of 100° with the curtain: Or, the exterior side may be formed and fortified inwards by drawing a line parallel to each of the interior sides; and when the angle is that of a polygon of more than five sides, the distance from the exterior to the interior sides should not be less than 100 yards. If a side extend from 360 to 520 yards, the perpendicular should be diminished to about fifty yards, and the faces of the bastions be made from 100 to 120 yards. When a side is very long, it may be divided into several parts of from 340 to 360 yards each, which may be fortified with flat bastions.
The ditch or fosse is an excavation of from twelve to twenty-four feet in depth, and from thirty to fifty yards in breadth, surrounding the rampart on the exterior side, and the earth dug out of which serves to raise the rampart and parapet. The side of the ditch next the place forms part of the escarp, the side next the country is called the counterscarp, and it is made circular opposite the salient angles of the works. In fig. 1 arcs are described with a radius of thirty yards, opposite the salient angles of the bastions, tangents to which are drawn upon the shoulders of the neighbouring bastions, and thus form the ditch.
The general dimensions of a ditch should be such that its excavation, or deblai, would produce sufficient earth, or remblai, for the formation of the works. The breadth varies from thirty to fifty yards, in order that, in passing across it to the assault, the enemy may, for a considerable time, be exposed to the fire of the works; and its depth must also be such as to render difficult the escalade of the parapet, as well as to prevent the besiegers at the crest of the glacis from being able to see to breach the lower part of the revêtement of the escarp. The line of the counterscarp is drawn from the rounding at the salient angles of the bastions upon the shoulders of the bastions next adjoining, in order that the whole of the ditch may be defended by the fire of the flanks of the collaterals bastions. Ditches are of three kinds; wet, dry, and such as may occasionally be rendered either wet or dry. The wet ditch is calculated to prevent sudden surprises or assaults, excepting during hard frost, as in the attempt made to surprise Bergen-op-Zoom in the year 1814; but, independently of this exception, the number of bridges of communication, which require continual repair, and the difficulty of making sorties, which a wet ditch creates, render it extremely inconvenient. A dry ditch, which is capable of containing works for its own defence, and by means of which communications round the works may more easily be maintained, is therefore preferable to a wet one; but the third kind, which unites the advantages of the other two, should, when practicable, be pre-
1 Although it has been common to employ the French toise as the standard measure for drawing plans, yet as the British linear measure of yards and feet has of late years been adopted by our engineers, we shall conform to the same usage. The tenaille is a work placed in front of the curtain. It is formed by the continuation of the lines of defence, at the distance of ten yards from the angle of the shoulder; the ends are then drawn parallel to the flanks of the bastions; it is made sixteen feet broad; the angle formed by the meeting of the two lines which determine its rear is then cut off, at the distance of ten yards, parallel to the curtain; and another line is drawn, at the distance of sixteen yards, parallel to this, and forming a small curtain upon the line of defence or front of the tenaille. The relief or height of the tenaille is determined by that of the neighbouring flanks, and it has a parapet of seven or seven and a half feet in height, and from twelve to fifteen feet in thickness. The use of the tenaille is to cover the postern gate, which is often made in the curtain or flank; when the ditch is dry, to protect the troops who may be formed behind the work for the defence of the ditch; and when the ditch is a wet one, to cover the boats which may be collected for the same purpose. It also serves to augment the defence, as its fire, from being more horizontal, and nearer than that from the flanks, is of course proportionally more effectual.
The ravelin or demi-lune is a work constructed opposite the curtain, and composed of two faces meeting in an outward or salient angle, with two demi-gorges formed by the counterscarp. Its use is to cover the curtain, the gates, and the flanks of the bastion. The ravelin is constructed as follows: Ten yards are set off along the faces of the bastion; from the shoulder an arc is described from the curtain, upon the perpendicular produced, with a radius of 160 yards; from this intersection lines are drawn bearing upon the points set off at ten yards from the shoulders of the bastion, but not further than the lines of the counterscarp, and at the intersection of the lines of the counterscarp or re-entering angle; and six yards are set off on the capital or line bisecting its angle, whence lines are drawn parallel to the lines of defence till they meet those of the counterscarp. Stairs, called pas-de-souris, are constructed here in order to facilitate the entrance of the ravelin from the ditch. The ditch in the ravelin, which is twenty-four yards in breadth, is made circular at the salient angle, and drawn parallel to the faces till it joins the main ditch.
The covered-way is a space of ten yards in breadth, extending all round the counterscarp of the ditch, and covered by a parapet of from seven to nine feet in height, with a banquette. The superior part of this parapet forms a gentle slope towards the country, which terminates at the distance of from forty to seventy yards; and this slope is called the glacis. The covered-way serves for drawing up troops in order to make sorties, and costs less than any other part of the works in proportion to the difficulty of taking it. In the salient and re-entering angles of the covered-way spaces are contrived which have been denominated places of arms.
The salient places of arms are formed by the circular parts of the counterscarp, and the prolongation of the branches of the covered-way till they intersect. The re-entering places of arms are constructed with two faces, forming a salient angle of 100° with the covered-way. The demi-gorges of the re-entering places of arms are generally from twenty-four to thirty yards; but when they are intended to contain a redoubt or entrenchment, they are from forty to forty-eight yards. The re-entering places of arms are meant to flank the branches of the covered way, and to contain the troops for its defence. The salient places of arms also serve for assembling the troops destined to defend the covered-way.
Traverses are constructed across the covered-way, upon the prolongation of the sides of the ravelins and bastions, perpendicular to the line of the counterscarp; they are from eighteen to twenty feet thick, and serve to cover the troops from the enfilading fire of the enemy. Other traverses should be constructed between these, so that the distance from the one to the other should not exceed thirty-six or forty yards. Openings are cut into the parapet of the covered-way about ten or twelve feet wide, in order to keep up the communication from one part to another round the ends of the traverses, which, however, may be shut by a gate when required. In the more improved systems of Cormontaigne and others, these passages are constructed in such a manner that each can be defended by the fire from the traverse in rear of it.
The glacis, as already stated, forms a gentle slope or declivity from the parapet of the covered-way towards the country, and varies from forty to sixty yards. Its parapet cannot be ruined by the fire of the enemy; it covers the revêtement of the body of the place; and being an inclined plane, it can be easily seen and defended from any part of the works.
The rampart is an elevation of earth, being the part of the works situated next to the town. It must be thick enough to receive a mound of earth, called the parapet, and also leave sufficient space behind it for working the guns, as well as room for the defenders to pass round freely. The ditch is immediately in front of the rampart, the faces of which are reveted or built up with stone walls, backed interiorly, at every fifteen or twenty feet, by buttresses or counterforts of masonry, to strengthen it. The rampart is divided into the interior slope, the terre-plein, the banquette, the parapet, and the exterior slope or escarp. See fig. 4, profile.
The revêtement or face of masonry around the work on both sides of the ditch, is intended to prevent the earth forming the rampart from falling into the ditch. To ascertain the proper thickness of masonry for this purpose has always been a work of considerable trouble and difficulty. Colonel Pasley of the royal engineers has given the following rules: 1st, For full scarped revêtements without berms, and for demi-revêtements having berms equal to one fourth the height of the masonry, the thickness of the wall should be seventeen sixtieths, and the length of the counterforts or buttresses one fifth of their height. 2dly, For demi-revêtements without berms, the mean thickness of the wall should be three tenths, and the length of the counterfort one fifth of the height. 3dly, For counterscarp revêtements, having only to retain simple terre-pleins, the mean thickness should be one fourth, and the counterfort one sixth of the height. In all these cases, Colonel Pasley supposes the revêtement to be countersloped, that is, to have the exterior slope in a vertical plane, and the interior face inclined, so that the base of the wall may be broader than its upper surface by one fifth of its height; and he also supposes the counterforts to be rectangular, and the intervals between their centres to be equal to four times their width. 4thly, He recommends that the foundations be made deeper in rear than in front, and that the courses of masonry form an angle with the horizon of about 10°; and, excepting at the exterior points, where it should be made horizontal, to prevent the rain from penetrating, that the interior face of the wall should be of an irregular form. In order to diminish the lateral pressure of the earth against the revêtements, several tiers of arches may be built between the counterforts in the form of segments of a circle.
The cordon is a round projection of stone, about a foot in diameter, which goes quite round the revêtement wall near the top, and serves to throw the drip of rain off the Fortification.
The profile or section of Vauban's first system is given in Plate CCXLVI. fig. 4, in order to illustrate the relative relief or height of the respective works, and also to show the command which each has over the others. By command is meant the vertical height of one work above another, or above the country. When the height of the rampart, including that of its parapet, is twenty feet, and that of the parapet of the covered-way is nine feet above the plane of the site, then the rampart will have a command of twenty feet over the country, and eleven feet over the crest of the covered-way; and the latter, again, will have a command of nine feet over the field. There are three sorts of command, namely, in front, in rear, and in enfilade. That in front is when any eminence directly faces the work which it commands; that in rear is when the eminence is behind the work; and that in enfilade is when the eminence is situated laterally on the prolongation of any line or work. The last, which is the most dangerous kind of command, is best remedied by raising the salient works exposed to it, or by erecting traverses. In drawing this figure, a line, called the line of site, and supposed to be the surface of the ground on which the fortification stands, is drawn, and perpendiculars are erected on it equal to the respective heights of the different parts of the works corresponding to the lines in the figure. Thus shows the terre-plein of the rampart, b the banquette or step to enable the soldiers to fire over the parapet, c the parapet, d the revetment, e the escarpe, f the countescarp, and so on.
2. Vauban's Second and Third Systems.
Having thus endeavoured to explain, with as much minuteness as possible, the principles of Vauban's first system, we trust, from what has been said, that no great difficulty will be experienced in understanding the methods of other engineers who have constructed works varying but little in the main from those prescribed by this system, whilst even these varieties have arisen from difference of situation and local peculiarities, more than from any other cause. The same general observation, indeed, applies to the other methods of construction followed by Vauban himself, who, in his second and third systems (see Plate CCXLVI. fig. 2) merely modified, according to circumstances, the principles upon which the first is based. When this celebrated military engineer was called upon to repair or improve the fortresses of Landau, Brisach, and others, and found these places already surrounded with strong walls surmounted by small towers at the angles, he did not, as some might have supposed, proceed to destroy these defences, but, with his accustomed judgment and ability, he immediately took advantage of them, and constructed, nearly in the same proportions as in his first system, large counterguards or bastions in front of the towers which crowned the angles of the wall. And by this method an important object was attained; for, as in front of each tower, or rather tower-bastion, there ran a ditch which cut off all communication between it and the counterguard, so the enemy, even if they should have succeeded in establishing themselves in the counterguard, would still have another ditch to cross, and another wall to breach, before they could attempt to give the assault.
There is so little difference between the second and third systems of Vauban, that a description of the former will be sufficient to enable the reader to distinguish and appreciate the peculiarities of the latter. In the second system, the interior side of the polygon, from the centre of one tower-bastion to that of the next, is supposed to be equal to 240 yards, and from its extremities, at the distance of twenty-four yards, perpendiculars are erected equal to thirty-six yards, for the flanks of the tower-bastions. A line is then drawn parallel to the interior side AB, till it meets the oblique radius of the polygon, or line drawn from the centre of the polygon, bisecting its angle, and this being done on both sides of the angle, forms the tower-bastion. The oblique radius is then produced seventy-eight yards, and lines of defence are drawn to the angle where the tower-bastion joins the curtain or line AB. On these lines of defence, the faces of the counterguard, or exterior bastion, are set off equal to yards, and from the point forming the shoulder, flanks are directed to a point set off on the line AB, at the distance of seventy yards from its extremities. From the salient angles of the tower-bastions arcs are described with a radius of fourteen yards for the breadth of the ditch, and tangents to these arcs are drawn parallel to the faces of the tower-bastion, but stopped where they would meet a line drawn from the salient angle of the tower-bastions, at the distance of twenty yards from the flanks.
The tenaille is the same as in the first system, excepting that, at its ends, it is carried down till it meets the line drawn between the flanked or salient angles of the tower-bastions. The ditch in front of the counterguards, or, in other words, the main ditch, is constructed in the same manner as in the first system. The ravelin is formed by setting off ninety yards from the re-entering angle of the counterscarp, and directing its faces to points set off on the counterguards, at the distance of twenty yards from the shoulders. A flank is formed by cutting off the corners of the ravelin at the distance of fourteen yards on its demigorge, and twenty on its face; and this flank serves for the placing of guns in such a manner that their fire may be directed into the counterguard, or into the ditch before them, as occasion may require. Again, at the distance of forty-eight yards from the re-entering angle of the counterscarp, lines are drawn parallel to the faces of the ravelin for the redoubt; a ditch is formed in front of this, and parallel thereto, about eighteen feet in breadth; and the redoubt thus constructed has a command of four feet over the parapet of the rampart, as the tower-bastions have over the counterguards. The covered-way and glacis are formed as in the first system. It sometimes happens that redoubts are constructed in the re-entering places of arms; in which case their demigorges are made from fifteen to forty yards, and their faces set off at an angle of a hundred degrees, as before.
3. Cormontaigne's System.
The difference between the systems of Vauban and Cormontaigne may easily be discovered by an examination of Plate CCXLVI. fig. 3. Vauban makes the faces of his bastions two sevenths of the exterior side, and Cormontaigne one third. Vauban, in his first system, produces the faces of his ravelin to the distance of ten yards upon the face of the bastion from the shoulder, and in his second and third systems, to the distance of twenty yards; but Cormontaigne makes the capital of his ravelins about 120 yards, and produces the faces to the distance of thirty yards from the shoulder; by which means the flanks are better covered, and the bastions and ravelins are enlarged. And this is an advantage; for he is thus enabled to construct a larger redoubt in his ravelin, the curtain and flank are also better covered, and, as the former is shorter, communications are more easily kept up between the bastions. Cormontaigne gives the same breadth to his covered-way as Vauban, but he arranges in a different manner the communication round the extre- mities of the traverses, as may be seen by inspecting the plate. By this chequer order, or zigzag line of communication, the passage round the extremity of one traverse may be defended by the fire of the other in its rear, or nearer to the body of the place, and the advance of assailants along the covered-way completely checked.
4. The Modern System.
The modern system, which is shown in Plate CCXLVII. fig. 2, varies but little from Cormontaigne's. Its perpendicular is one sixth of the exterior side, and the faces of the bastions are one third. The flanks are at right angles with the lines of defence, whereas in Vauban's system they form an angle of about eighty-two degrees; which is not so good, because, in the modern system, the guns placed in the flanks can fire straight along the ditch without being moved or turned on their platforms. The ravelin is formed by setting off thirty-four yards from the shoulder angle of each bastion along the face, which line forms one side of an equilateral triangle, the vertex of which, opposite the centre of the curtain, forms the salient angle of the ravelin. The redoubt of the ravelin is formed by drawing its faces parallel to those of the ravelin from the shoulder angle of the parapet of the bastion; and it has flanks with a ditch about twenty yards in breadth. The coulisse in the bastion is drawn parallel to the faces of the bastion, at the distance of forty-eight yards. The ditch on the faces is ten yards in width, but there is no ditch on the flanks. The couprise, or cavalier retrenchment, is drawn perpendicular to the faces of the bastions, at thirty-four yards for the countescarp of the couprises, whilst the scarps are at ten yards, and parallel to these.
5. Coehorn's System.
This system, which is shown in Plate CCXLVII. fig. 1, is particularly adapted for the low and swampy country of Holland, where alone it has been practised. It is not, therefore, deemed necessary here to enter into any details respecting it. The great width of the ditch, which is nearly twice as broad as in Vauban's systems, and the narrow space between the flanks, constitute the principal differences between the methods of these celebrated engineers; a difference, as already observed in speaking of Coehorn, caused by the different descriptions of ground on which their respective works were erected.
6. Outworks.
Plate CCXLVII. fig. 3, shows several kinds of outworks, as a horn-work g, tennillons k and k, bonnet d, lunettes a and d, an entrenched bastion e, bardeau f, and caponnière h. These, and other works of a similar description, are constructed for the purpose of occupying some of the ground which might otherwise be of service to the besiegers; but their application must of course depend upon certain localities, and the judgment of the engineer must therefore determine, in each particular place, which is best adapted to the ground, and most proper to be employed with reference to the general defence of the place.
ARMAMENT OF FORTRESSES.
Having thus endeavoured to describe as briefly as possible the principal systems of fortification, it only now remains for us, before quitting this branch of the subject, to say a few words respecting the means of defending a place after it has been fortified. And here we may observe, that it is difficult to lay down any exact rules as to the proportion of ordnance, ammunition, and stores of every kind required for the defence of a fortified place, seeing this must necessarily vary according to the particular situation of each fortress, the system on which its works have been constructed, and the species of attack to which it may be exposed. If, for example, one of the sides be covered by a morass, swamp, or any other obstruction which it is difficult or perhaps impossible to surmount, it must be obvious that, in this case, a smaller proportion of artillery will be required than if the fortress were equally accessible on every side; and, on the other hand, a maritime fortress, accessible at all points, will necessarily require for its defence a larger proportion of ordnance than if it were only assailable on one or a few of these points. Where every front is equally exposed to attack, all must of necessity be equally prepared.
On this subject, however, there have been established certain maxims, of which the following appear to be the most important: First, the proportion of ordnance, ammunition, and stores, should never exceed the quantity necessary for a brave and resolute defence. Secondly, those points which are considered as being most exposed to attack should be most completely armed, whilst the partial armament of the remaining points may suffice. Thirdly, for each of the faces of the bastions which are liable to be attacked, five or six pieces of ordnance should be allotted; for each of the flanks of these bastions, four; for the faces of the ravelins, from five to seven; for the lunettes, when there are such, four pieces of ordnance should be reckoned; besides two or three pieces for each of the places of arms in the covered-way. Supposing, therefore, that one front of a place is to be completely armed, the proportions of ordnance required will be, for the faces of the bastions from ten to twelve pieces, for the two interior flanks from six to eight, for the faces of the ravelins from five to seven, and for five places of arms from ten to fifteen; making the total of ordnance for one front from thirty-one to forty-two pieces. Fourthly, when a place is exposed to attack on two consecutive fronts, the armament of each should be augmented one half; when it is threatened with attack on detached fronts, the armament should, in that case, be doubled. Fifthly, each of the other fronts should merely be provided with such a proportion as to secure it against insult. Lastly, from the foregoing maxims, it appears that a hexagon, having only one front exposed to attack, requires from fifty-eight to sixty-eight pieces of ordnance on such front, whilst in more extensive places, six, eight, or ten pieces should be added for each additional front.
The next consideration is the proportion which the several kinds of ordnance should bear to one another. And here let it be remembered that ordnance of the higher calibres is not the only description which ought to be employed. In many cases medium, and even light guns are more efficacious; for when only troops or working parties are to be fired at, light guns will answer every purpose, as the range of the shot is nearly equal to that of larger guns, and they are of course much more manageable, and may be worked with greater rapidity. But short guns of heavy calibre are best adapted for the flanks; and, generally, the large or heavy ordnance should only be employed to destroy the besiegers' batteries and dismount their guns. The flank guns being only required for the defence of the ditch, short pieces of large calibre, as carronades, which throw a heavy charge of grape or canister shot, are the most proper to be employed. The light guns, as they can easily be withdrawn, should be placed on the covered-way and places of arms, and on outworks of every description. The heavy long guns and mortars, as they are not so easily moved, should be within the body of the place, and as they require a great quantity of ammunition, they should be less frequently used, and only upon urgent oc- Fortification.
A judicious economy of ammunition is a duty incumbent upon every governor or commandant of a fortified place attacked. The conduct of General Chassé in the defence of the citadel of Antwerp was a model in this respect. From the commencement till the close of the attack, scarcely a single shot was needlessly expended by the garrison.
ATTACK AND DEFENCE OF FORTIFIED PLACES.
Having thus treated of that important branch of fortification which is denominated permanent, and which, being applied solely to the defence of towns, is not liable to be destroyed except by an enemy, we now proceed to consider the attack of fortified places, the general system of which was introduced by Vauban, and so far perfected by that great engineer that it has ever since served as a model for the plans of his successors.
"La résolution des sièges," says the Mareschal, "est une affaire de cabinet. Elle est une naturelle de la supériorité que l'on croit avoir sur ses ennemis; mais leur exécution étant une des plus sérieuses, des plus importantes, et des plus difficiles parties, elle demande aussi le plus de mesure et de circonspection." He then goes on to state that the success of sieges depends on several circumstances, such as, "1. Du secret, sans lequel il est difficile de réussir; 2. Des forces que l'on a sur pied pour attaquer les places des ennemis et défendre les siennes; 3. De la disposition des ennemis; car s'ils sont réunis, et aussi forts que nous, ils peuvent nous empêcher d'en faire: 4. De l'état des magasins les plus à portée des lieux sur lesquels on peut entreprendre; 5. De la conjonction des temps, parce que tous ne sont pas propres aux sièges, et rien n'étant plus ruineux que ceux d'hiver, on les doit éviter tant qu'on peut; 6. Des fonds nécessaires à leurs dépenses; car l'argent est le nerf de la guerre, sans lui on ne saurait réussir en rien. Ce sont là des mesures à prendre de longue main, qui doivent être dirigées à loisir; et après tout cela, quand on croit les avoir bien prises, souvent tout échappe; car l'ennemi, qui n'est jamais d'accord avec vous, pourra vous interrompre.... Il faut bien peser toutes ces considérations, avant que de se déterminer; et prendre toujours si bien son temps, que l'ennemi ne puisse vous tomber sur les bras avant vos établissements."
A siege, therefore, being one of the most arduous undertakings in which an army or corps d'armée can be employed; one in which the greatest fatigue, hardships, and personal risk are encountered; and in which the prize can only be won by complete victory; it is obvious that, upon the success or failure of such an enterprise may depend the fate of a campaign, sometimes that of an army, and perhaps even the existence of a state. Of this the failures before Pavia in 1525, before Metz in 1552, before Prague in 1557, before St. Jean d'Acre in 1799, and before Burgos in 1812, present instructive examples. By the first, France lost her monarch, the flower of her nobility, and all her Italian conquests; by the second, she was saved from destruction, whilst thirty thousand of her enemies perished; by the third, the greatest warrior of his age, Frederick the Great, was brought to the very brink of destruction; by the fourth, the most successful general of France, and perhaps the greatest commander that any age or country has produced, was stopped short in his career of victory; and by the last, a beaten enemy gained time to recruit his forces, concentrate his scattered corps, and regain that ascendency of which the victory at Salamanca had for a time deprived him. Innumerable other instances of the disastrous consequences usually attendant on the failure of sieges might easily be produced; but those which have just been referred to are sufficient to establish the importance of the undertaking, and to show that the dearest interests of a country may frequently be staked on the sure and speedy reduction of a fortress.
It is therefore of the greatest importance to a state that the sieges undertaken by its armies should be carried on in the best and most efficient manner possible, or, in other words, that by a due combination of science, labour, and force, these operations should be rendered not only short, but certain, and unproductive of any great expenditure of life. But the sieges undertaken by the British have almost never united these three indispensable conditions; and with regard to those which took place during the contest in the Peninsula, it is well known that various defects of organization, and particularly the want of a body of men, such as sappers and miners, trained to the labour required at sieges, not to mention the inexperience of the engineers, and an inadequate supply of matériel, necessitated a departure from all established principles and rules of attack, and consequently led to a waste of life wholly unprecedented in modern sieges. Till late in 1813 the army was unattended by a single sapper or miner: regular approaches were therefore impracticable: it was necessary, in almost every case, to take the bull, as the saying is, by the horns; the last operation of a siege scientifically conducted, namely, battering in breach, was the first, or almost the first, undertaken: and the troops were marched to the assault whilst the defences remained nearly entire, and exposed to every species of destruction which the unreduced means of the besieged could bring to bear against them. The army of a country which has outstripped all others in the useful arts and in mechanical improvements, was left wholly unprovided with those appliances which at once economise labour and life, and serve to render both most effectual for the purposes to which they are applied. But, notwithstanding this great anomaly, which is chargeable against the government alone, and not against either the nation or the army which in the most adverse circumstances so nobly sustained its reputation, it may be observed that, in all periods and in all countries, the means employed for the reduction of fortresses have generally increased and become more overwhelming and irresistible in proportion to the advancement of knowledge and the improvement of the useful arts; and that in Europe during the last two centuries, the extensive diffusion of wealth and knowledge, accompanied by an unprecedented development of talent, all more or less directed towards military movements, has caused the results of sieges, and indeed of almost all the operations of war, to depend much less on individual exertion or casual displays of heroism, than on mere combination and expenditure. This may be made apparent by a slight retrospect of the sieges of the sixteenth century.
At the period here referred to, the art of disposing the several works of a fortress so as to cover each other, and to be covered by their glacis from the view of an enemy, was either unknown or disregarded; whilst the small quantity of artillery in use, its unwieldiness, and the great expense and difficulty of bringing it up, occasioned so little to be used in sieges, that the chief object in fortifying towns was to render them secure against escalade and surprise, by means of lofty walls or altitude of situation. All places fortified prior to the sixteenth century are invariably of this construction. And as the simplicity of the fortresses to be attacked necessarily gave the same
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1 De l'Attaque et de la Difense des Places, pp. 1 and 2. Hague, 1737, 4to. character to the operations directed against them; so, in those days, every thing was effected by daring courage, without the aid of science; and gallantly contending in individual combat, or fearlessly confronting danger, were considered as the highest qualities of a besieger. Thus the contest dragged on for months, in petty but sanguinary affairs, and the most persevering or the most hardy troops, however ill organized or supplied, were the most dreaded, and not unfrequently the most successful. But when artillery became more moveable, and large quantities began to be employed in sieges, lofty and exposed walls no longer opposed any adequate barrier; large breaches were speedily effected; places which had formerly resisted for months were carried in a few days; and hence, in order to restore an equality of defence, it became necessary to screen the ramparts from distant fire. The attempt to gain security by concealment rapidly advanced towards perfection, whilst the means of the besiegers remained the same; and between the middle of the sixteenth and commencement of the seventeenth century, works were so skilfully disposed and so well covered, that the defence of towns obtained a temporary superiority over the attack as the latter was then practised. Of this the obstinate and successful defences made by the Dutch against the Spaniards during the reigns of Philip II. and Philip III. may be cited as remarkable examples.
But unhappily for this pre-eminence, Vauban appeared on the scene, and, supported by Louis XIV., who brought to the attack of fortresses a vast and costly preparation in ordnance, ammunition, and materials, perfected in the early offensive campaigns of that monarch a covered mode of attack, which, by a singular combination of science and labour, and by the steady advances of a few brave men well trained to such work, rendered comparatively easy the reduction of places capable of ever defying the rude violence of multitudes. These increased means of attack, to which it was found impossible to oppose a successful resistance, caused the art of concealment or covering to be further studied, till at length, in well-constructed fortresses, not a single wall remained exposed to view, and the sap and the mine became as necessary as the gun and the mortar to the success of a besieger. To render this intelligible to the general reader, it may be proper to introduce here a descriptive sketch of the progress of a modern attack, from the excellent work of Sir John Jones, already referred to.
"The first operation of a besieger," says that able and experienced engineer, "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 with a body of men, part carrying entrenching tools, and the remainder armed. The former dig a trench in the ground parallel to the fortifications 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 despite 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, embracing all the fortifications to be attacked; and along this road, guns, waggons, and men securely and conveniently move, equally sheltered from the view and the missiles of the garrison. Batteries of guns and mortars are then constructed on the side of the road next the garrison, to oppose the guns of the town, and in a short time, by superiority of fire, principally arising from situation, silence all those which bear on the works of the attack. After this ascendency is attained, the same species of covered road is, by certain rules of art, carried forward, till it circumvents or passes over all the exterior defences of the place, and touches the main rampart wall at a spot where it has been previously beaten down by the fire of the batteries erected expressly for the purpose in the more advanced parts of the road.
"The besiegers' troops being thus enabled to march in perfect security to the opening or breach in the walls of a town, assault it in strong columns; and being much more numerous than the garrison defending the breach, soon overcome them, and the more easily as they are assisted by a fire of artillery and musketry directed on the garrison from portions of the road only a few yards from the breach; and which fire can, at that distance, be maintained on the defenders of the breach until the very instant of personal contention, without injury to the assailants. The first breach being carried, should the garrison have any inner works, the covered road is by similar rules of art pushed forward through the opening, and advanced batteries are erected in it to overpower the remaining guns of the place; which effected, the road is again pushed forward, and the troops march in security to the assault of breaches made in a similar manner in those inferior works, and invariably carry them with little loss. But as it is always an object to preserve the life of even a single soldier, so, when time is abundant, the loss of men attending on the assault of breaches under these favourable circumstances may be avoided, by pushing up the covered road through the breach, without giving the assault, and thus, by art and labour, the strongest defences frequently fall without any exertion of open force."
From this description it must be obvious that the most important object at a siege is to carry forward the covered road to the walls of the place; that all the other operations are secondary to and in furtherance of such an advance; and that hence the efficiency of armies at sieges depends upon their ability to complete the road at a small expense of life. But in forming this covered road, different degrees of difficulty are experienced in proportion as it advances. At its commencement, the work, owing to the distance from the fortifications, which is usually about six hundred yards, and not being straitened for space, can easily be performed by the common soldiers. But when the road or trench has arrived within a fair range of musketry, or three hundred yards from the place, then particular precautions are required; yet the work at this stage is not so difficult as to prevent its being executed by soldiers who have had a little previous training. At the last stage, when the approaches have been pushed close to the place; when to be seen is to be killed; when mine after mine blows up the head of the road, with every officer and man on the spot; when the space becomes so confined that little or no front of defence can be obtained; and when the enemy's grenadiers sally forth every moment to attack the workmen, and deal out destruction to all less courageous or weaker than themselves; then the work becomes truly hazardous, and can only be performed by selected brave men, called sappers, who have acquired the difficult and dangerous art from which they derive their name. An indispensable auxiliary to the
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1 Journals of Sieges in Spain, by Colonel Sir John T. Jones; Preliminary Observations on the Attack of Fortresses. Fortification.
Sapper, however, is the miner, who, in the exercise of his art, requires even a greater degree of skill, conduct, and courage than his principal. The duty of a miner at a siege is to accompany the sapper, to listen for and discover the enemy's miner at work, and to prevent his blowing up the head of the road, either by sinking down and meeting him, in which case a subterranean conflict ensues, or by running a gallery close to that of his opponent, and forcing him to desist from working by means of suffocating compositions, and various arts of chicanery, the knowledge of which he has acquired from experience. Without the aid of skilful miners, sappers would be unable to execute that part of the covered road forming the descent into the ditch, not to mention other portions in the formation of which the assistance of the miner is equally indispensable; and without their joint labours and steady cooperation, no besiegers' approaches ever reached the walls of a fortress.
But a siege, though it calls for great personal bravery, unremitting exertion, and extraordinary labour in all employed, yet, if scientifically prosecuted, is alike certain in its progress and its result. More or less skill and exertion in the contending parties may in some degree prolong or abridge its duration; but the sapper and the miner, when skilfully directed and adequately supported, will ultimately surmount every obstacle. On the other hand, sieges undertaken by armies destitute of these auxiliaries, as was that of the Duke of Wellington in Spain, are hazardous in the extreme. Their only chance of success consists in scrutinizing the exterior of a fortress, in order to discover some spot whence, from the irregularity of the ground, or fault of construction, the main escarp wall may be seen at a distance sufficiently great to enable the ordinary working parties to approach with the covered road, and there to establish batteries for breaching the wall or forming an opening through it into the place. When this is effected, the troops at once advance to the assault of the breach, as in the sixteenth century, thus losing the shelter of the covered road at the moment when the fire of the place becomes most powerful and destructive; and as the fire of the besiegers distant batteries is necessarily suspended during the assault, in order to avoid killing their own storming party, the garrison can therefore with impunity mount their ramparts and employ every kind of weapon, missile, and instrument in their defence. All the chances are thus in favour of the besieged; for should the columns of attack, under all these disadvantages, arrive in good order at the brink of the ditch, they must descend into it by a wall from fourteen to sixteen feet in depth, which cannot fail to break their order and throw them into confusion; and as no new formation can be attempted in a spot where death is incessantly showering down on them, the assailants rush to the breach more like a rabble than a solid column. From this moment success hinges on the individual and confident bravery of the officers and troops, and the unshrinking firmness of the general commanding, in at once encouraging and supporting their efforts. But although these qualities, when united in a high degree, may, at a great sacrifice of life, enable the assailants to overcome all resistance, yet an assault of this nature, attempted under ordinary circumstances and feelings, has almost invariably proved unsuccessful. Indeed it may be laid down as the general result of experience, that should an army unprovided with sappers and miners, and the necessary materials and means to render their services efficient, be opposed to a place fortified according to the modern system, with its walls completely covered, all the usual methods to reduce it would prove unavailing; no period of time nor sacrifice of men would be sufficient to purchase success, and the prudent course would be to decline an attempt pregnant with hazard, perhaps ruin.
Having thus given a general description of the methods of attack, we shall now subjoin, on high authority, a view of what is considered as necessary for the proper defence of fortified places. An order issued by the French minister of war in 1813 contains directions on the subject which are almost universally applicable, and therefore deserve a place here. Every commander is directed to consider his garrison as liable to be unexpectedly attacked, and to pass at once from a state of peace into one of war or siege, either by rebellion, by unlawful assemblies, by the presence of an enemy, by surprise, or by sudden assault; in a word, by unforeseen causes, of which the history of war offers numerous examples. He is therefore ordered, even in time of peace, to fix his plan and arrangement for defence, according to such supposed attacks as may appear most probable, and to determine, for the principal cases which may be likely to occur, the necessary posts, reserves, and movements of the troops, and to take measures to ensure the due and active cooperation of every corps of the garrison. He ought, particularly, to make himself thoroughly acquainted with, firstly, the ground beyond the place which may be within the circle of action, of investment, and of attack; secondly, the fortifications of the place, its interior, its buildings,
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1 Journals of the Sieges in Spain, Preliminary Observations.—"These considerations," says Sir John Jones, to whom we are indebted for the above account of the various modes of attacking fortified places, "have for many years had their due weight with the great powers of Europe, and induced them to form and keep up, as integral portions of their military strength, every necessary auxiliary for the reduction of fortresses; and their sieges have in consequence become certain and comparatively bloodless. But England, constitutionally jealous of permanent military establishments, always disconcerted military organization and military preparation till the hour of need; and with respect to sieges, they being of rare occurrence, and moreover exclusively offensive operations, even carried her jealous feelings beyond the bounds of rational prudence; for, possessing a corps of officers professionally educated and well grounded in the science of attack and defence, she denied them every requisite establishment to render their acquirements availling, and most unreasonably expected her armies to reduce the skilfully fortified and well-covered places of the nineteenth century with means inferior to those brought against the exposed and ill-constructed places of the sixteenth and seventeenth centuries." And what was the immediate consequence of this irrational jealousy and niggardly parsimony? Contrary to all ordinary calculation, the forces experienced by the French in Spain were reduced; but at what a prodigious expenditure of life was this effected? In the several attacks upon Badajoz, two of which, from extrinsic circumstances, proved abortive, a little army was sacrificed; as many more, in short, as would have been sufficient for the consumption of ten sieges undertaken with adequate means, and conducted according to the ordinary rules of science. But this is not to be understood as involving any reflection against the military talents of the general or the professional ability of the engineers. General Foy, in his work on the war in the Peninsula, has indeed made such a charge, condemning the mode of attacking fortresses adopted by the British in Spain as unskilful and inefficient, and bringing it forward as indisputable proof of the low state of military knowledge in the army. But it should be remembered that the adoption of this mode was not a matter of choice, but of necessity; and that if it was in its own nature rash, hazardous, and inefficient, the fact of its having been directed against Ciudad Rodrigo and Badajoz with such rapidity of development and certainty of result as to outstrip the calculations of the French marshals, deceive the vigilance of French governors, paralyse the science of the French engineers, and baffle every defensive effort of the French garrisons, is surely no evidence of deficiency in military talent and professional skill. The objections to this mode of attack are insurmountable and decisive; that it succeeded in the instances referred to is merely a proof what British soldiers, even when acting under the greatest disadvantages, are capable of accomplishing. its military edifices or establishments; thirdly, the garrison, the means of the place in artillery, in ammunition, and in other stores of every kind; fourthly, the population to be subsisted in time of siege, the men capable of bearing arms, the master and journeymen artificers fit to be employed either on the works or in case of fire; and, fifthly, the provisions, materials, tools, and other resources which the town itself and surrounding country can furnish, and which it might be necessary to secure in case of siege.
In order to enable governors and commanders to comply with these instructions, which are equally clear and precise, the minister proceeds to detail their principal duties, according to the circumstances in which they may find themselves placed; but for these we must refer to the general order itself, which is a masterpiece of its kind, and in all probability emanated directly from Napoleon himself. Its object appears to have been to produce a belief that by taking proper precautions, and making a full use of means previously provided, the defence might be rendered equal, if not superior, to the attack; and although it is acknowledged on all hands that the idea of attaining such an advantage for the defence is, generally speaking, fallacious, yet the importance of the directions embodied in the order is not on that account diminished, and where they are duly observed, the nature and extent of the resistance must be materially increased.
**Attack of the Citadel of Antwerp.**
For the elucidation of the principles above stated, we now proceed to give a sketch of the attack on the citadel of Antwerp; first, because this was the most regular and scientific siege which had taken place for many years; and, secondly, because, as a practical operation, an account of it must not only be more interesting, but at the same time more instructive, than any description whatsoever of the formal theoretical plans which are usually drawn in the military schools.
The French army employed to cover and conduct the attack of the citadel of Antwerp, in November and December 1832, was placed under the command of Marshal Gerard, and amounted to 54,000 infantry, 6000 cavalry, and 6450 engineers, artillery, and pontonniers, making a total of 66,450 men, and 14,300 horses, with 144 pieces of siege and 78 of field artillery. On the 24th of November Marshal Gerard established his head-quarters at the village of Berchem, about 2500 yards from the citadel, and issued orders to commence operations in the evening as soon as it became dark. The garrison of the citadel, under General Baron Chassé, amounted to 4470 men, with 144 pieces of ordnance of all calibres, and abundance of ammunition and stores.
At eight o'clock p.m. on the 29th November the French troops destined for this service consisted of 18 battalions, 900 artillery, and 400 sappers, in all about 17,140 men, assembled at the depôts of intrenching tools. The flank companies of these brigades, supported by twelve eight-pounders and a strong piquet of cavalry, formed the covering party under the direction of General Haxo, by whom and the officers of his department (the engineers) the first parallel and approaches were traced out, whilst General Niègre and the officers of artillery marked the sites of the projected batteries. The first parallel leaned on the covered-way of the right face of Montebello, and extended towards Kiel, its nearest point being about 325, and its farthest 435 yards from the advanced front of the citadel. The distance covered by the first parallel, from right to left, was 1870 yards, and that by the approaches 3750 yards. The communications from the right and centre debouched from the Malines Chaussée, in the village of Berchem, parallel to the road leading from that village to the Harmony and St Laurent; that from the left commenced near to the garden called Heinrich's; whilst a fourth, on the extreme right, sprung from the covered-way of the left flank of Montebello, opposite to the first traverse.
On the second night, from 30th November to 1st December, five approaches were pushed on in front of the first parallel; two in the direction of the capital of the Toledo bastion, two upon that of the Lunette St Laurent, and one, being the fifth, terminating in a place of arms on the extreme left. From the 1st to the 2d December two zigzags were added to the approaches; one from the centre, in the direction of the gorge of St Laurent, and the other on the right, diverging towards the curtain, between the Toledo and Fernando bastions. The badness of the weather sadly incommodeed the workmen, and prevented the artillery getting the guns into battery. Between the 2d and 3d December four zigzags were made in front of the approaches on the right and centre, and half a parallel was formed to complete the place of arms constructed on the left during the night of the 30th November. The heads of the zigzags were pushed to within 135 yards of the glacis. The batteries Nos. 1, 2, 3, 4, 5, 6, and 9, with two for mortars in the rear, were armed, and ready to be unmasked at a moment's notice. The arming of Nos. 7, 8, and 10, on the extreme left, was impeded by the difficulties of the ground. From the 3d to the 4th December, the second parallel was traced and commenced, its right leaning on the foot of the glacis of the counter-guard, its centre and right 130 yards distant from the place of arms in the covered-way of the Toledo bastion, and its left towards the right of the covered-way of St Laurent, at 90 yards from the crest, and 15 from the foot of its glacis. The length of the second parallel was 1250 yards, and, together with its approaches from the first parallel, it occupied 3025 yards of ground. By the greatest exertions batteries Nos. 7, 8, and 10 were armed during the night. This completed the armament, and, at 11 a.m. on the 4th, the embrasures were unmasked, and the signal being given, the batteries opened their fire from centre to flanks, and maintained it steadily during the day.
From the 4th to the 5th of December an approach was pushed on from the second parallel, almost in a direct line upon the salient angle of St Laurent, and an entry was made into the covered-way by a return to the left. The garrison discovered this, and opened a sharp fire from the Lunette; a lodgment was, however, effected near the spot usually occupied by the first traverse. At this time the garrison suffered much from the fire of the besiegers. From the 5th to the 6th the lodgment made the previous night in the covered-way of the salient place of arms of St Laurent was prolonged as far as the first traverse. But the besieged kept up so vigorous a fire that the French engineers were obliged to renounce the flying and adopt the full sap. The zigzag in the counter-guard, being about three feet in width and four in depth, was conducted along the parapet, nearly to the extremity of the right flank, and within 180 yards of the counterscarp of bastions Toledo and Fernando; and two lodgments, blinded with fascines, were made in the parapet for six rampart guns to enfilade the covered-way of the Toledo bastion. In the mean time a steady fire was kept against Kiel, the ravelin in its rear, and the Paciotto bastion. From the 6th to the 7th a battery of 24-pounders near the village of Burcht on the left and Hoboken on the right opened on the gun-boats which flanked the French post at the Melk Huys. It was intended to assault St Laurent this evening; but as the lunette was found to be too well protected by trous-de-loup, the project of storm was abandoned, and the regular method of descent, passage, and mine, determined on. Between the 7th and 8th of December a shell penetrated the blindness of the laboratory, and setting fire to loaded bombs and other combustibles, caused considerable havoc. A battery for six mortars, E, on the right between Nos. 3 and 4, now opened its fire; another, F, also for six mortars, was traced behind the centre of the parallel; and platforms for four mortars were laid down near Montebello. The fire of these batteries was directed on the Toledo bastion and the buildings within it. On the previous day jets of smoke and flame were seen to issue from the Great Barracks, and, in spite of every exertion on the part of the garrison, the whole building soon became involved in a general conflagration, which raged with such fury that by the evening of the 8th it was entirely consumed.
From the 9th to the 10th of December the operations against St Laurent were renewed with great activity, and the sap advanced to the crotchet of the second traverse, whilst that intended to debouch upon it from its right was likewise pushed on. The principal operation of the night, however, was the opening of the third parallel, 130 yards in advance of the second, its right debouching beyond the Boom Chaussée, from the branch running into the covered-way of the counter-guard, and its left uniting with the boyau parallel to the foot of the glacis of St Laurent. At this time the garrison suffered much from the vertical fire of the mortars and howitzers, especially the great mortar, and the new-model eight-inch howitzer. Until the year 1822, the eight-inch howitzer in common use in France measured three feet six inches French, and weighed 1096 lbs., or twenty-three times the weight of the loaded projectile, whilst its calibre was equal to a solid shot of 80 lbs., and contained 65 ounces of powder. The new-model howitzer is an improvement on the Russian licorne and the Spanish heavy howitzer, perfected by Colonel Paixhans. The raft for the blinded descent into the ditch was brought up to the lodgment, and a second descent d'escalier was commenced to the left of the first. The third parallel was, at the same time, improved and widened. A little after dusk on the 10th the besieged made a sortie, which was driven in, but not until damage enough had been done to occupy the French all the night of the 10th and morning of the 11th in repairing it. From the 11th to the 12th three rafts were got ready, and placed in the descents to the ditch; they were about twelve feet by eight. At dusk the miners returned to the escarpe, and, in an excavation made the previous night, fixed two petards, which, by their explosion, produced a fissure in the wall; and a sergeant having immediately entered the hole, commenced a gallery under the centre of one of the arches. At 11 A.M. on the 12th the battery mortars, H, on the extreme right of the second parallel, opened their fire, which, combined with that from the others, told severely on the Toledo bastion. The miners still continued their work under the Lunette St Laurent, and commenced chambers for three mines. The fourth parallel was widened during the day.
Between the 12th and 13th of December the miners were at work in the chambers under St Laurent, which were not yet completed. On the right the covered-way of the left face of the Toledo bastion was crowned to within sixty-five yards. From the 13th to the 14th, after nearly sixteen nights of open trenches, the arrangements for the assault of St Laurent were completed, and orders were issued to prepare for the storm. Much, a great deal too much, was said of this out-work, defended by little more than a hundred men, one five-and-a-half inch howitzer, two coehorn mortars, and a six-pounder. The mine being reported charged, the blinded descent into the ditch was Fort pierced as soon as it became dark, and everything got ready for the assault. Three storming parties, consisting of the flank companies of the 65th regiment of the line, were posted in readiness, with a column of reserve; and at 5 A.M. on the 14th, every preparation being completed, the match was applied to the saucissons of the mines. After a few moments of suspense, three successive explosions took place, and the escarpe immediately presented a wide and practicable breach. The fascines for crossing the ditch had been injured by the explosions; but after a little delay the storming party entered almost without opposition, and made prisoners one lieutenant and forty-eight rank and file, the others having escaped into the citadel. Thus fell the Lunette St Laurent.
After this, operations were carried on against the citadel, and at 11 A.M. of the 21st December the battering in breach commenced, and continued for two days. At length, on the 23rd, when a practicable breach had been formed, and Marshal Gerard was about to deliver the assault, the garrison surrendered, after as gallant a defence as any recorded in military history, though more remarkable for its passive than its active character. When Marshal Gerard, accompanied by the French princes, entered the fortress, they found General Chassé in a casemate in the Alba bastion, which he had occupied during the siege. On their progress from the gate to the governor's quarters, they passed through a scene of desolation and ruin, intermixed with painful and disgusting objects, which baffles all description. The whole, indeed, presented an unparalleled chaos of black and smouldering destruction; and, with the exception of the principal powder magazine, two or three service magazines, and the hospital, not a building was standing. The terrepleins of the bastions were ploughed into deep ruts by the shells; the gorges were encumbered with heaps of fallen rubbish; and though the casemates and subterranean communications were not perforated, all of them had sustained damage from the incessant explosion of shells, and they emitted an offensive, nay, almost insupportable odour, caused by the number of men who had been crowded into these vaults. Everything was of course said by the victors to console and flatter the vanquished. When Count Gerard took his leave of General Chassé, he observed to the brave veteran, "that it was high time to surrender; that he had gallantly and honourably done his duty, and that he ought not to have held out a day longer." With a fortress reduced to a heap of ruins, a garrison exhausted and exterminated, and a breach sufficiently wide to admit a column formed upon a front of a hundred, it would not have been bravery, but madness, to attempt, under such circumstances, to stand an assault.
This operation, so instructive in a military point of view, is also remarkable as having occurred in a time of general peace. It would be out of place here to enter into any detail of the complicated series of events and negotiations out of which so singular an occurrence arose: we shall therefore content ourselves with observing, generally, that Great Britain and France, as joint guarantees for the integrity and independence of Belgium, having failed in every attempt to procure the evacuation of Antwerp by means of negotiation, were obliged, by the faith of treaties, to have recourse to force. Hence the siege, politically considered, is to be viewed merely as an ejectment executed against the king of Holland, who had refused to renounce possession, unless compelled to do so.
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The account of the siege given above is abridged from that published in the United Service Journal, and which is decidedly the best that has yet appeared. The following is a list of the different batteries, with the direction of their fire respectively:
| Number of Batteries | Twenty-four Pounders | Sixteen Pounders | Eight-inch Howitzers | Ten-inch Mortars | Distance in Yards | Direction of Fire | |---------------------|----------------------|-----------------|---------------------|------------------|-------------------|------------------| | 1 | 6 | ... | 2 | ... | 535 and 550 | Battering the left face of Toledo, and gorge of St Laurent. | | 2 | ... | 2 | 2 | ... | 500 | Ricocheting the left face of Toledo. | | 3 | 4 | ... | 2 | ... | 640 | Battering the left face of the Ravelin. | | 4 | ... | 3 | 2 | ... | 650 | Ricocheting left face of the Ravelin. | | 5 | 6 | 2 | 1 | ... | 680 and 430 | Battering right face of Toledo, and ricocheting left of Toledo. | | 6 | ... | 2 | 2 | ... | 700 | Ricocheting left face of Toledo. | | 7 | 6 | 2 | 1 | ... | 380 and 700 | Ricocheting left face of St Laurent, and battering right face of Paciotto. | | 8 | ... | 3 | 2 | ... | 465 | Ricocheting left face of Ravelin. | | 9 | ... | 6 | ... | ... | 820 | Battering salient angle of Paciotto. | | 10 | 8 | ... | ... | ... | 650 and 520 | Battering left face of Ravelin, and Lunette of Kiel. | | A | ... | ... | ... | ... | 850 | Not armed. | | B | ... | ... | ... | ... | 1000 | Body of the Citadel. | | C | ... | ... | ... | ... | 1050 | ... | | D | ... | ... | ... | ... | 850 | ... |
The French brought against this place 66,450 men, 14,300 horses, and 222 guns of all descriptions; and they lost during the siege 108 killed, and 695 wounded, total put hors de combat 809. The Dutch had 4937 men in the garrison, of whom they lost 122 killed, 369 wounded, and 70 missing, total 561.
Siege of Dantzig.
Having thus given an example of an interior and passive defence, we shall now, in further illustration of the principles already laid down, advert to one of a different if not opposite kind. The siege of Dantzig, whether considered with reference to the magnitude of the operation, the difficulties to be surmounted by the besiegers, or the active and varied character of the defence, was certainly one of the most memorable events in the campaign of 1807. Before the war of 1806 and 1807, the fortifications had been much neglected, because, from the position of the place, no one suspected that it would have to sustain a siege. But when the battles of Iena and Auerstadt had entailed destruction on the Prussian army, and laid open the kingdom, General Manstein, who commanded at Dantzig in the absence of Field-marshal Kalkreuth, the titular governor, had laboured with much activity in improving the exterior works, and particularly in causing them to be strongly palisaded. It is necessary, therefore, to describe the principal defences at the period when the place was invested by Marshal Lefebvre, at the head of the tenth corps of the Grand Army, and immediately before the commencement of the trenches on the 1st of April 1807.
The city of Dantzig, traversed by the Moltau, was surrounded with large ditches filled by that river, the waters of which, retained by several sluices, formed, to the eastward, a vast inundation, which, reaching on one side to the suburbs of Ohra and St. Hallbrecht, and on the other to the dikes of the Vistula, extended about four leagues, and covered two thirds of the eastern fronts. On the north, the Vistula runs about two hundred and sixty yards from the covered-way, leaving a space between the left bank and the glacis of the place, consisting of an impracticable marsh, intersected by some canals; and at its embouchure, distant nearly three miles, the banks were defended on the right by the fort of Weichselmunde, and on the left by an intrenched camp in the small island of Neufahrwasser, intended to cover and protect the arrival of such succours as might come from the seaward. The ground adjoining the banks of the Vistula being intersected by canals and covered with marshes, was extremely unfavourable to a besieger, as it rendered it difficult for him to form establishments or raise works of proper solidity, and forced him to extend his quarters, disseminate his troops, and multiply his posts. At the period in question, this inconvenience was the more severely felt, because the besieging force was inferior in numbers to that of the garrison, and it required the most vigilant caution to occupy numerous posts without unduly weakening it. The Fortification.
Fortifications between the place and the fort of Weichselmunde was maintained by a series of redoubts constructed on the borders of the Vistula, and particularly by the advantageous position of the isle of Holm, which enabled the besieged so to approximate the fire of the place to that of the fort as only to leave between them an interval of about fourteen hundred yards, and also to communicate with Weichselmunde by the canal of Laack, in spite of batteries which the besiegers might establish at Schellmühl. The French, therefore, could not attempt to throw a bridge over this part of the Vistula until they had made themselves masters of the isle of Holm. On the west, two chains of hills, separated by the valley of Schiditz, covered this part of the enceinte; and the prolongations of these hills were crowned by two forts, that of Bischopsberg and that of Hagelsberg, which, being connected by continuous intrenchments, formed a second enceinte, flanked upon one side by the inundation of the Moltau, and upon the other by the left bank of the Vistula. This new enceinte, though constructed of earth, and without revêtement, was nevertheless secure against assault; and as the covered-way, as well as the foot of the scarp and counterscarps, bristled with strong fraises, which served instead of revêtements, the besiegers had no hope of succeeding by a coup-de-main, and were therefore obliged to proceed by a regular attack.
From this description of the defences of Dantzig, it is easy to perceive that the difficulties attending the operation must have been very great. The principal of these, as stated by General Kirgener, who, until the arrival of General Chasseloup, directed the attack, were, 1st, that Marshal Lefebvre had at first an army inferior to that of Marshal Kalkreuth, and that this army was in a great measure composed of new troops, all those destined for the siege not having then arrived; 2dly, that, owing to the badness of the roads and the inclemency of the season, the artillery experienced the greatest difficulty in bringing up its convoys, whilst the establishment of the batteries was retarded, and a scarcity of ammunition sometimes prevailed; 3dly, that the place requiring an immense circumvallation, which, in fact, could not be completed until after the arrival of reinforcements, the corps of troops which occupied the quarters were extremely weak, and hence could neither furnish a sufficient number of workmen at a time, nor even the number of men necessary for guarding the trenches; and, 4thly, that the besiegers had no good plan of the place, no idea of the depth of the ditches, and that, as the accidents of ground in front of the fortifications were extremely diversified, they could only be reconnoitred in proportion as the works advanced. These circumstances, the necessity of concentrating the greater part of the troops close to the camp of Neufahrwasser, by which succours arriving by sea might debouch, and, lastly, the advantage which the besieged had been able to preserve of remaining masters of part of the suburbs, determined the chief engineer, after the investment had been effected, to direct the principal attack against the Hagelsberg, and a false one against the Bischopsberg fort. The true point of attack was the long branch of lines in the plain connected with the bastion on the right of the Hagelsberg; "c'était là le défaut de la cuirasse;" but, for the reasons above stated, General Kirgener was induced to direct his approaches against the fort itself.
As the details of this great siege would fill a considerable volume, all that our limits permit us to attempt is merely to indicate the principal occurrences. On the 1st of February 1807 the troops of General Dombrowski began to approach Dantzig, and took up a position at Mewe, upon the left bank of the Vistula. On the 15th General Ménard, commanding the Baden contingent, arrived at the same point, and repulsed a detachment of the garrison of Dantzig, which had advanced from Dirschau to attack him. On the 23d General Dombrowski, having been reinforced, received orders to attack a large detachment of the enemy which occupied an advantageous position at Dirschau and its environs. The combat here was obstinate and sanguinary; but the Prussians, though entrenched in a church and a churchyard, were dislodged and driven back, chiefly by the Poles, who, exasperated by their long resistance, put to death without mercy all who fell into their hands. After the combat of Dirschau, General Stein no longer sought to obstruct the distant approaches. The troops destined to form the besieging army now arrived in succession, and the parc of artillery began to be formed. On the 12th of March Marshal Lefebvre found himself in a condition to close in on the place; and the troops of the garrison having withdrawn, he distributed his own in the following positions: A battalion of French light infantry at Ohra, a Saxon battalion at St Halbrecht in the Burgerfeld, and two others at Tiefensee and Kemlade; the Poles occupied Schönfeld, Kowald, and Zunkendin; some battalions took post at Wommenberg, Neukau, Schudelkau, and Smiekau; the Saxon cuirassiers and light horse were stationed at St Halbrecht and Guisehkena; the 19th regiment of French chasseurs at Burgfeld, and the 23d at Schudelkau; the Baden dragoons and hussars at Wommenberg, and the Polish lancers at Langenfurt. On the 16th the marshal attacked the village of Stolzenberg, which he carried after a warm resistance, as he did also the suburb of Schiditz to which the Prussians had retired; and on the 18th the place was entirely invested, with the exception of the eastern part, which, by the isle of Nehrunig, communicated with Königsberg. Field-marshal Kalkreuth now arrived in Dantzig, and assumed the command of the place. The next operation of the besiegers was the attack of the isle of Nehrunig, which, after a severe and protracted struggle, was carried in the most gallant manner, and measures immediately taken to secure possession of this important conquest. A bridge was also established on the Vistula, and various works constructed to check the attempts of the enemy either on the side of Dantzig or on that of Pillau. At this time the governor, who, besides the burgher militia, had under his command a garrison of 18,000 men, made a sortie for the purpose of destroying the works already commenced by the besiegers; but the attempt failed, and the Prussian columns were compelled to retreat into the place without having obtained the smallest success upon any point.
As it had been decided that the principal attack should be directed against the fort of Hagelsberg, favoured by two false attacks, the one directed against the intrenched camp at Neufahrwasser, and the other against Bischopsberg, and also by two other secondary attacks on the left bank of the river, ground was broken on the night of the 1st and 2d April, at the distance of sixteen hundred yards from the palisades. The approaches were pushed forward with the greatest vigour, and on the night of the 11th the second parallel was commenced by means of the flying sap. On the morning of the 12th the marshal ordered the batteries to be armed, which was accordingly done.
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1 This officer, the head of the engineer staff, and one of the most distinguished in that branch of the service, fell in the field of battle at Bantzen, where he received his death-wound from the same ball which killed Duroc, the grand marshal of the palace, and the intimate friend of Napoleon. On the 13th the enemy made a sortie in force, attacked the Saxons with great impetuosity, carried a redoubt constructed upon the mamelon of Hagelsberg, and even penetrated to the head of the trenches; but they were ultimately repulsed, though not without difficulty and loss. By the 23d all the batteries of the first and second parallels, and those of Stolzenberg, were armed, and emplacements were provided for field howitzers, in order to throw shells into all quarters of the city. At daybreak on the 24th the batteries were unmasked, and though the garrison returned the fire with the greatest vivacity, that of the besiegers soon obtained the ascendancy, committing great ravages in the place. Being apprised of this circumstance, Marshal Lefebvre summoned the governor, who replied in a manner worthy of himself. The fire of the mortar and reverse batteries continued during the 25th, in the course of which a new battery was constructed between the low flanks of the Stolzenberg; and the direction of some others changed, in order to batter the right bastion of Bischopsberg, the fire of which had greatly incommode the French batteries. During the day of the 26th, the fire on both sides was exceedingly animated; but at seven in the evening, that of the garrison suddenly ceased, and a column of six hundred Prussian grenadiers, followed by two hundred workmen, soon afterwards saluted out of the place. As the sortie had been foreseen, however, preparations were made to repulse it, which was done by a combined attack in front and on both flanks, in consequence of which the whole column was either killed or taken. Meanwhile the works were vigorously pushed forward at all points. The batteries of Stolzenberg were united with the attack on the Bishopsberg; emplacements were prepared for batteries à ricochet; at the attack of the Lower Vistula the works were continued, and a tongue of land situated at the extremity of the isle of Holm taken possession of and isolated by means of a cut; whilst at the principal attack the greatest exertions were made to prolong the right of the third parallel, and enlarge the communications. On the 30th April the batteries of the besiegers, augmented by several pieces which had arrived from Warsaw, thundered on the place, in different quarters of which conflagrations now appeared; and the besieged replied by the fire of all the batteries of the front of the attack, directing more than thirty pieces on a redoubt, which fired with the greatest effect. But as the fire of the besiegers had made little impression on the exterior fortifications, which were of earth, it was during the first days of May directed chiefly against the palisades, in order to facilitate the assault of the place; and the utmost activity was at the same time evinced in extending, improving, and urging forward the attack; whilst, on the other hand, the garrison showed equal vigour in obstructing the approaches and destroying the works of the besiegers. In fact, notwithstanding the address of the French artillery, that of the garrison still remained effective, because it had not been possible to ricochet the lines of the fortifications, and the resources of the besieged in munitions of all kinds were more considerable than those of the besiegers.
On the urgent recommendation of General Chasselay, who had by this time assumed the direction of the attack, it was now decided that the isle of Holm should be assaulted, as the possession of it would enable the besiegers to construct new batteries, to take in reverse the front of the attack. The besieged had spared no pains for the preservation of this important post. In the night of the 6th and 7th of May, however, it was attacked, and, after a desperate resistance, carried; whilst the possession of it was secured by works added to the intrenchments which had just been stormed, and the batteries were turned against the place. At the principal attack the fire of the besiegers had also mastered that of the besieged; and Marshal Lefebvre was preparing to assault the fort of Hagelsberg, when a Russian corps d'armée under the command of General Kamenskoi arrived by sea, and disembarked at the entrenched camp of Neufahrwasser.
At the moment of landing his troops, General Kamenskoi was ignorant of the capture of the isle of Holm, and he was disconcerted to find such an obstacle to his communications with the place. This occasioned delay, which proved fatal to his enterprise; for had he attacked immediately on landing, it is not improbable that he would have succeeded. It was only on the 15th of May, however, being the fourth day after the disembarkation, that he resolved to make an attempt to succour the besieged city. He began to debouch at four in the morning, and, under cover of a brisk cannonade, formed his force, consisting of eleven to twelve thousand men, in four columns of attack. The onset was impetuous, and at first the Russians gained ground, thrice attempting to penetrate the French line; but they were ultimately repulsed at all points, and forced to retreat with great loss to the entrenched camp. Field-marshal Kalkreuth made no attempt to second this attack by means of a general sortie, which would have placed the French between two fires; and by its failure the fate of Dantzig was decided. Such was the issue of the only effort made by the allies to relieve this important fortress.
The works of the besiegers were now pushed forward with redoubled vigour; and in the course of the following day preparations were made for the assault of Hagelsberg. Foreseeing this, Marshal Kalkreuth resolved to make a last effort to destroy the nearest works of the besiegers, and for this purpose ordered a grand sortie, which took place on the evening of the 20th May; but although the Prussians fought with all the fury of despair, they were at length driven back, and pursued even into the ditch of the place. On the 21st the army of siege was reinforced by the arrival of the troops of Marshal Mortier, part of which had remained before Colberg; the marshal himself quickly followed; and orders were immediately issued for the assault of Hagelsberg. Before giving the signal, however, Marshal Lefebvre again summoned the governor of Dantzig, who, having no longer any hope of being succoured, and convinced that the besiegers were in a condition to make themselves masters of the fort of Hagelsberg, showed a disposition to capitulate. A suspension of arms was accordingly agreed to, and this was followed, on the 24th of May, by a capitulation, the principal conditions of which were similar to those which the field-marshal himself had granted to the garrison of Mayence in 1793.
FIELD FORTIFICATION.
Field fortification is the art of constructing all kinds of temporary works in the field. An army intrenched, or Fortification.
Fortified, in the field, produces, in many respects, the same effect as a fortress; for it covers a country, supplies the want of numbers, stops the advance of a superior enemy, or, if he chooses to risk a battle, obliges him to engage at a disadvantage. "In a war of march and manoeuvre," says Napoleon, "if you would avoid a battle with a superior army, it is necessary to intrench every night; and to occupy a good defensive position. Those natural positions which are ordinarily met with are not sufficient to protect an army against superior numbers without recourse to art. Those who proscribe lines of circumvallation, and all the assistance which the science of the engineer can afford, deprive themselves gratuitously of an auxiliary which is never injurious, almost always useful, and often indispensable. It must be admitted at the same time that the principles of field fortification require improvement. This important branch of the art of war has made no progress since the times of the ancients. It is even inferior to what it was two thousand years ago. Engineer officers should be encouraged in bringing this art to perfection, and in placing it on a level with the rest."
Whenever Napoleon had time and occasion for strengthening his position by field-works, he acted upon the principles recommended in the above extract, as almost all his predecessors had done. In the wars which followed the revolution of 1688, in those of Queen Anne's reign, and during the Seven Years' War, we find the commanders of each period, William III., the Duke of Marlborough, Marshal Villars, Marshal Saxe, Frederick II., and Marshal Daun, practically exemplifying their conviction of the great utility of field-works. A few redoubts saved Peter the Great at Pultowa, and enabled him to gain a decisive victory over his formidable antagonist; and at Borodino, some slight open field-works, thrown up by the Russians, caused the French great loss, and rendered too costly to be of almost any avail the victory which, by incredible efforts of gallantry, they gained. It has been argued by some, against intrenchments and field-works, that they have oftener been carried than successfully defended, and that hence incommensurate importance has been attached to them. But it should be remembered, on the other hand, that victory in such circumstances has generally been purchased at an expense which rendered it in effect equivalent to defeat; and that a practice which the greatest commanders of ancient and modern times have approved and followed, cannot be one of doubtful utility. At Austerlitz, where the contending armies were nearly equal, Napoleon was preparing to superintend the construction of intrenchments when he found himself called upon to receive battle; and in Portugal, the Duke of Wellington showed to what importance the art of the engineer might be turned for influencing, not merely the fortune of a campaign, but the fate of a cause. The lines of Torres Vedras, which formed the ne plus ultra of the powerful French army under Massena, and from which the tide of war was rolled back broken into Spain, were perhaps the most remarkable works of the kind ever constructed.
"Lisbon," says Sir John Jones, "being situated at the extremity of a peninsula formed by the sea and the Tagus, it is plain that if an army be so posted as to extend Fort across the peninsula, no enemy can penetrate into the city without a direct attack on the army so formed. It was on this principle that the lines covering Lisbon were planned by Lord Wellington. Nature drew the rude outline of a strong defensive position, and art rendered it perfect. A tract of country thirty miles, extending from the mouth of the Zizandra on the ocean, to Alhandra on the Tagus, was modelled into a field of battle; mountains were scarped perpendicularly, rivers dammed, and inundations formed; all roads favourable to the enemy were destroyed, and others made to facilitate the communications of the defenders; formidable works were erected to strengthen and support the weak parts, whilst numerous cannon places, on inaccessible points, commanded the different approaches to them, and gave an equality of defence to the whole position." These lines were not continuous and connected works; they consisted of independent forts, redouts, flèches, redans, batteries, &c., placed as to command and enfilade every approach, and to support each other by a cross or a flanking fire. The first line occupied a front of twenty-nine miles between the sea and the Tagus; and by means of telegraphs intelligence could be conveyed from one extremity to the other in a few minutes; whilst the troops were disposed in masses in the rear of the works, ready to move upon any point that might be attacked, by interior communications shorter than any by which the enemy could advance. "The aim and scope of these works," says Colonel Napier, "was to bar the passes, and to strengthen the fighting positions between them, without impeding the movements of the army. These objects were attained; and it is certain that the loss of the first line would not have been injurious, save in reputation, because the retreat was secure upon the second and stronger line, and the guns of the first were all of inferior calibre, mounted on common truck carriages, and consequently immovable and useless to the enemy." Both lines occupied a front of fifty miles, on which there were erected one hundred and fifty forts, mounting in all about six hundred pieces of artillery.
Before this formidable position, defended by a double line of works, and by an army massed and ready to move upon any point by interior communications, the French remained five months, wasting their numbers and resources; until at length, finding it utterly impracticable to force any part of even the exterior line, they were obliged to retire from Portugal, closely followed and harrassed by the army which they had previously driven out of Spain. Yet though the lines of Torres Vedras were thus perfect in themselves, and though one of the ablest of the French generals and a veteran French army were foiled before them, it is not meant to refer to this system of separate field-works as a model to be followed on all occasions; for whilst the old method of covering a considerable front by a continued line of regular bastions and curtains has been universally condemned by modern engineers, it is nevertheless certain that there are situations where a partial application of continued lines may be most judiciously made. In fact, it is not by any fixed rule, but from the
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1 Military Maxims of Napoleon. 2 War in Spain, p. 124. The French army which invaded Portugal under Massena consisted of three corps, under Marshals Ney and Junot and General Regnier, amounting in all to 66,000 infantry and 6000 cavalry, besides a strong body of the imperial guard, which crossed the Pyrenees after the invading force had commenced its march from the neighbourhood of Salamanca. The force collected to oppose this threatened invasion did not exceed 48,000 infantry and 3900 cavalry, of which about a half was composed of Portuguese levies, yet untried in any general action, and of which a very unfavourable opinion still continued to be entertained. In point of numbers, and still more in the composition of their army, therefore, the French had a decided superiority; but all their advantages were neutralised by the defensive position of Torres Vedras. 3 History of the War in the Peninsula, vol. iii. nature of the ground and of the position to be defended, that the species of works calculated to be most useful should, in every case, be determined.
It must be obvious indeed that even a limited knowledge of the art of war opens a wide field for the exercise of the talents and resources of engineers in field fortification; but the possession of a military coup-d'oeil, or of that intuitive judgment which comprehends at a glance the true bearing or character of objects as well as events, is necessary to enable them to convert theoretical stores of information to the best practical uses. In passing through a country, it requires an experienced eye to seize quickly on whatever it presents calculated to prove advantageous or disadvantageous to an army destined to attack or defend it; to appreciate the value of villages, stone-enclosures, and broken ground; to know where to dam up rivers, to scarp heights, to form abattis, trous-de-loup, and other obstacles; to select the best situations for field-forts and redoubts, and the best emplacements for batteries; and to arrange all the defensive means employed, with reference to the number of troops destined to act upon the different parts of the line, so that the movements of the defenders may not be obstructed or retarded, and the communications throughout may be short and easy. The variety of ground, however, upon which military operations are for the most part carried on, precludes the possibility of laying down fixed rules in regard to this subject; the accidents of ground, and the peculiar circumstances of each individual case, must, as already observed,
Redans, or simple heads, fig. 1, Double redans, or queues d'hironde, fig. 2, Tenaille heads, fig. 3, Bastioned heads, fig. 4, Redoubts, fig. 5, Star-forts, fig. 6, Bastioned forts, fig. 7, Lines à crémaillères, fig. 8, Lines of redans, fig. 9, Lines of tenailles, fig. 10, Lines of bastions, fig. 11, Lines at intervals, fig. 12,
are the names given to the various tracings of the first class, or open works.
The first class are of the simplest kind of field-works, and serve as a mere cover in front of avenues, bridges, causeways, and the like; but being quite open at the gorge, they are only suited for defence when their extremities rest on rivers, or obstacles which prevent their being turned, or when within the full sweeping fire of works in their rear. To increase the strength of a redan, its faces are sometimes broken into a kind of flank, as in fig. 1, Plate CCXLIX. The double redan, or queue d'hironde, fig. 2, is considerably stronger, as the re-entering faces defend each other; the tenaille heads in situations which require a greater extent of front; and the bastioned heads are also employed in similar circumstances. See fig. 3 and 4.
Redoubts are works closed on all sides; they are constructed of a square or polygonal figure, but most commonly square, as, when of this form, each front can furnish a strong perpendicular fire. Provision should be made for defending the ground before the angles, which, however, are sometimes rounded or cut en crémaillère, so that a fire may be delivered from them. See fig. 5.
Star-forts were proposed in order to remedy the defects of redoubts having the ground before them undefended by a flanking fire, so that a cross fire might be delivered from the adjacent sides. But, according to Jomini, "star-forts are the very worst description of fortification; they cannot have flanks, and the re-entering angles take so much from the interior space that it is impossible to place troops and artillery in them sufficient for their defence;" an opinion confirmed by the practice of Sir Richard Fletcher and Sir John Jones in the construction of the lines of Torres Vedras, where the trace of the redoubts was made subservient to the conformation of the ground, to the object in view, and to the protecting them as much as possible from the fire of the enemy's position.
In bastioned forts, fig. 7, the principles of construction correspond with those detailed in permanent fortification; and the flanking defence thus obtained for the ditch is nearly perfect. As bastioned forts are only constructed in cases of great importance, no labour or expense should be spared in the formation of such works.
Forts with demi-bastions, fig. 12, are objectionable, as the ditches are only defended by an oblique fire from the sides. The parapets of these works should be of sufficient thickness to resist the fire of the heaviest guns that can be brought against them. In some cases, however, the parapets need only be strong enough to resist the fire
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1 Shaw's Course of Field Fortification, p. 6, et seqq. To the author of this useful tract we have been indebted for valuable assistance in the compilation of the present article, the plates connected with which are engraved from drawings either executed by him or under his inspection. Fortification.
of light field-guns, whilst in others it will be sufficient if they serve as a cover to the men within them against musketry. The latter kind is generally that which is thrown up in an evening after taking up a position, and which, if the army does not move next day, it may be considered as necessary to strengthen in some parts, according to circumstances.
Continued lines, or connected works, are resorted to in order to enclose the front, or to connect important works or forts. The most simple tracing is that of redans joined together by curtains, fig. 9; but as the ditches of these curtains can only be defended by an oblique fire from the faces of the redans, this defect may be remedied by breaking the curtains so as to form nearly right angles with the faces of the redans, in which case they are called lines of tenailles.
Lines en crêmaillère have long faces, with flanks perpendicular to these, in order to defend their ditches. When these faces can be directed towards ground upon which it is impracticable to establish enfilading batteries, the construction is considered as good.
Bastioned lines are the strongest trace which can be given to continued lines, when the ground will admit of such. A perfectly regular trace is only suited for level ground. The ditches in field-works are often sloped en rampe towards the adjoining flanks, in order that the déblai, or quantity of earth excavated, may not exceed the remblai, or quantity contained in the mass of the rampart or parapet, a circumstance which often occurs in field-works, where there is seldom any rampart, and only cover sufficient for the defenders.
Lines with intervals, fig. 14, shows the general trace of lines of this kind. The salient works should never be beyond the range of musketry from the re-entering works, and the angles of defence between the two lines should be as near as possible to right angles.
Têtes-de-pont, or bridge-heads, are works generally open at the gorge, and whose flanks rest upon a river, in order to cover one or more bridges. The best situation for these works is the re-entering sinuosity of a river. As tête-de-pont, fig. 13, are usually constructed for the purpose of enabling a retiring army to cross a river in order, and to check an enemy pressing upon it, the tracing and profile should be such as to secure a double advantage to the greatest extent possible. In Sir Howard Douglas's able work on the Construction of Military Bridges will be found much valuable scientific information upon this important subject.
To field-works there are usually added a variety of obstacles, in order to render the approaches more difficult to the enemy: such as palisades, barriers, abattis, trous-de-loup, chevaux-de-frise, harrows, and crozes-feet.
Palisades are strong stakes fixed in the ground, and well sharpened at the upper extremities. They are sometimes placed horizontally in the face of the parapet, in which case they are called frises. Barrier-gates, for closing the entrances of field-works, should be made strong enough to resist a sudden attack: they are always placed on the most inaccessible side. Abattis are lines of felled trees of considerable size, strongly bound together and picketed down, with the smaller branches cut off, and the remainder sharpened and pointed towards the enemy. They are interlaced as much as possible. Abattis, well disposed, present a formidable obstacle. Troux-de-loup are rows of pits, made before a work, in the form of inverted cones, having each a strong palisade or stake in the middle. Chevaux-de-frise are formed by inserting iron-pointed stakes, five or six feet in length, into a heavy beam of wood, which will thus, if it be square, present four projecting spears, and if hexagonal, six. Chevaux-de-frise are generally chained together in a line, in order to cover the Perif ground required; and sometimes they are so constructed as to revolve on an axis. Harrows, such as those ordinarily used in husbandry, are recommended to be spread, with the teeth uppermost, over the ground by which an enemy, particularly cavalry, is likely to advance to the attack. Crozes-feet are pieces of iron, with four points, each four or five inches long, projecting in different directions, and also intended to impede the advance of cavalry.
For the defense of open towns and villages, the following methods, recommended by the French minister of war in 1814, are considered as the best that have yet been suggested: "To admit of a town being advantageously intrenched, it is necessary that it should not be commanded within any short distance, that the houses should not be of a construction easily set on fire, and that its extent should not be out of proportion to the means and time at the disposal of the defenders. The first thing to be done is to clear the approaches to the town, by levelling houses, hedges, shrubberies, and whatever may favour the assailants. Wood ought to be cut two feet from the ground, that it may serve to impede the advance of the enemy without masking the fire of the defenders. The next object is to form or complete the enclosure round the town. For this purpose advantage is taken of buildings, walls, and fences applicable to the defence. The openings which remain must be closed by palisades, stockades, or ditches strengthened by abattis. All streets leading out of town must be barricaded. The barricades must be sufficient to resist field artillery, and high enough not to be easily got over; and they ought to be flanked by loopholing the neighbouring houses. When pressed for time, carts filled with dung and the wheels taken off, sand-bags, bales of wool or cotton, and furniture taken from the neighbouring houses, all form good barricades. If there should be any old castle, church, or large substantial building, it should be converted into a keep, by blocking up useless entrances, loopholing walls, and surrounding them by a ditch or abattis. If a town is situated near a stream or river, by which part of it may be covered by inundations, this should never be neglected."
Villages are intrenched on similar principles, and being generally surrounded by gardens with live hedges, the latter may be made use of in forming the lines of defence. If there should only be sufficient troops to defend part of a village or town, a part only should be intrenched and separated from the rest by means of carts and barricades. If there are very few houses, it may be necessary to confine the defence to the church or churchyard, which may in all cases serve as a sort of keep.
The destruction of bridges. Nothing is of greater consequence to a retiring army than to be able to destroy the bridges in its rear, in order to retard the advance of the enemy. Its safety, nay even its existence, may depend upon the success with which this operation is performed. In order to destroy a stone-bridge, a trench in the form of a cross is made in the crown of the arch, the branches of which are about ten feet in length, and sunk to the top of the arch-stones. A hundred and sixty pounds of powder are placed in each cut or trench for an arch three feet thick, strong planks are then laid over the powder, and the whole being well covered with rubbish, the fire is communicated by means of saucisson or long powder-hose. Stone bridges are also destroyed by simply cutting a trench about eighteen inches deep across the crown of the arch, and placing in it 345 pounds of powder covered in the manner just described. This quantity has been found sufficient to destroy semicircular arches of twenty-five feet in span, and three feet in thickness at the key. Wooden bridges may be destroyed in different ways;