From the 13th to the 14th, was crowned to within 65 yards. after nearly sixteen nights of open trenches, the arrangements for the assault of St Laurent were completed, and orders were issued to Too much value was set on this outwork, prepare for the storm. defended by little more than a hundred men, one five-and-a-half inch howitzer, two Coehorn mortars, and a six-pounder. The mines being charged, the blinded descent into the ditch was pierced as soon as it became dark, and everything prepared for the assault. Three storming parties 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 the match was applied to the saucissons of the mines. Three successive explosions took place, and the escarp 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 until the 23d. When a practicable breach had been formed, and Marshal Gerard was about to deliver the assault, the garrison surrendered, after a gallant defence, remarkable, however, When Marshal for its passive rather than for its active character. Gerard entered the fortress, General Chassé was found in a caso- his leave of General Chassé, he observed "that it was high time to Battering the left face of Toledo, Battering the left face of the Ra Ricochetting left face of the Ra- Battering right face of To.edo, and Ricochetting left face of Ravelin. ciotto. Battering left faro of Ravelin, Body of the Citadel Do. Battering the right face of To- Battering the Batardeau Battering the left face of Ravelin. Do. Do. Do. Do. Breaching battery, Counter-battery against the left. flank of Fernando. Six plerriers on the Ravelin and Terrepleins and rampart of To- Out of their force of 66,450 men, the French lost during the 4937 men in the garrison, of whom they lost 122 killed, 869 wounded, and 70 missing-total 561. A careful comparison of the details of this siege with the general principles which have been enunciated will enable the reader to recognize the importance of the following maxims: 1. Independently of the great amount of labour to be provided for in the construction of parallels, approaches, and batteries, there will be a daily drain upon the besieger's forces by casualties, so that he can scarcely expect success unless his original preponderance in numbers has been such as to leave him at the final moment of assault in a condition to attack the diminished garrison with an overwhelming force. In addition, therefore, to a covering army when external relief is threatened or anticipated, the besieging army should be from four to five times the strength of the garrison, or even more, should the nature of the ground add to the ordinary difficulties of approach. This superiority of force is necessary to give celerity and steadiness to the operations, which would otherwise be tedious and interrupted. 2. A perfect investment is not merely expedient but indispensable. So long as any portion of the enceinte of a fortress is left open the garrison is able to recruit its strength from without, and it is relieved from that moral depression which must oppress men when closed up within a narrow space, and exposed, day after day, to fatigue and danger. Under such circumstances there seems to be no limit to the power of defence, as fresh supplies of men enable the besieged to add intrenchment to intrenchment, and it is only possible to overcome him by determined, reiterated, and overwhelming assaults. Such were the circumstances of Sebastopol; the system of attack forced upon the allies never enabled them to isolate even the southern section of the fortress, and the means of communication between the south and north remaining available fresh troops were continually brought to the south side, and a superiority in numbers given to the defenders over the attacking force. It ought not therefore to be a matter of surprise that the progress of the siege was slow. 8. Good and secure lines of communication are most essential, as there ought to be no interruption after the ground is broken and Neither in the attack nor in the defence the siege has commenced. should guns be fired idly, or from distances and positions from which their fire would be useless or even uncertain; but when the proper distance has been ascertained, battery should succeed battery as the works of approach advance, and no interval for rest or for the repair of injuries should be allowed to the besiegers. 4. The importance of advanced works was well exemplified at the siege of Antwerp, where the whole force of the attack was directed against the advanced lunette St Laurent, whilst the defence, though good, had not the advantage of the collateral defence of the lunette Montebello (see Plate XI.). Where the garrison is an army, such works afford the best means for an obstinate defence, and, by forcing the besieger to act on the circumference of a larger circle, diminish very much his ordinary advantage of concentration. Siege of Dantzic. Having thus given an example of an interior and passivę defence, we shall now, in further illustration of the principles already laid down, advert to an example of a different kind. The siege of Dantzic, 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 it was not anticipated that it would have to sustain a siege. But when the battles of Jena and Auerstadt had entailed destruc. tion on the Prussian army, and had laid open the kingdom, General Manstein, who commanded at Dantzic in the absence of Field-marshal Kalkreuth, the titular governor, laboured with much activity in repairing the walls and the palisades, and in completing the enceinte. It is necessary, therefore, to describe the principal defences at the time the place was invested by Marshal Lefebvre, at the head of the tenth corps of the grand army, and before the commencement of the trenches on the 1st of April. The city of Dantzic, traversed by the Mottlau, was surrounded with large ditches filled from 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 Oliva and St Halbrecht, and on the other to the dykes of the Vistula, extended about four leagues, and covered two-thirds of the eastern fronts. On the north the Vistula runs about 260 yards from the covered-way, leaving between the left bank and the glacis of the place an impracticable marsh intersected by canals; 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. A the period in question this inconvenience was the more severely felt, because the besieging force, though nominally 18,000 strong, was inferior in numbers to that of the garrison, which consisted of 12,000 Prussians and 3 Russian battalions, and it required the most vigilant caution to occupy numerous posts without unduly weak ening it. The communication between the place and the fort of Weichselmunde was maintained by a series of redoubts constructed on the borders of the Vistula, and parti cularly by the advantageous position of the isle of Holm, which continued the defence of the place to the fort with, the exception of an interval of about 1400 yards, and reudered the communication with Weichselmunde by the canal of Laack secure in spite of any batteries which the besiegers could 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 Schidlitz, covered the enceinte; and the prolongations of these hills were crowned by the two forts of Bischopsberg and Hagelsberg, which, being connected by intrenchments, formed a second enceinte, leaning upon one side on the inundation of the Mottlau, and upon the other on the left bank of the Vistula. This new enceinte, though constructed of earth and without revetment, was secure against assault, and as the covered-way as well as the foot of the scarps bristled with strong fraises which served instead of revetments, the besiegers had no hope of succeeding by a coup-de-main, and were therefore obliged to proceed by regular attack. From this description of the defences of Dantzic, 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, first, that Marshal Lefebvre had at first an army inferior to that of Marshal Kalkreuth, all of those destined for the siege not having then arrived, and that this army was in a great measure composed of new troops; secondly 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, the establishment of the batteries was retarded, and a scarcity of ammunition sometimes prevailed; thirdly, that the place, which could not be completely invested because the approach from seaward was in the hands of the British, required 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 could neither furnish a sufficient number of workmen, nor even the number of men necessary for guarding the trenches; and fourthly, that the besiegers had no good plan of the place, and did not know the depth of the ditches, and 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, joined to 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 the advantage which the besieged had in retaining the mastery 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 reasous above stated, approaches were directed against the fort itself. As the details of this great siege would fill a considerable volume, all that our limits permit is merely to indicate the principal occurrewski began to approach Dantzic, and took up a position at rences. On the 1st of February 1807 the troops of General Dom. Mewe, upon the left bank of the Vistula. On the 15th General Menard, commanding the Baden contingent, arrived at the same point, and repulsed a detachment of the garrison of Dantzie, 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 intrenched in a church and a churchyard, were dislodged and driven back, chiefly by the Poles, who, exasperated by their long resistance, put to death Dirschau, General Manstein no longer sought to obstruct the distant without mercy all who fell into their hands. approaches. The troops destined to form the besieging army now arrived in succession, and the formation of the park of artillery was commenced. On the 12th of March Marshal Lefebvre found himself After the coinbat of in a condition to close in on the place; and the troops of the garri son having withdrawn, he distributed his own in the following positions:-a battalion of French light infantry at Oliva, a Saxou battalion at St Halbrecht in the Burgerfeld, and two at Tiefensee and Kemlade; the Poles occupied Schonfeld, Kowald, and Zunkkau, and Sniekau; the Saxon cuirassiers and light horse were endin; some battalions took post at Wonnenberg, Neukau, Schudelstationed at St Halbrecht and Guirseh kens; the 19th regiment of French chasseurs at Burgfeld, and the 23d at Schudelkau; the Baden dragoons and hussars at Wonnenberg, and the Polish lancers at Langenfurt. On the 16th the marshal attacked the village of Stolzer. berg, which he carried after a warm resistance, as he did also the suburb of Schidlitz, to which the Prussians had retired; and on the 18th the place was invested, with the exception of the eastern part, which, by the isle of Nehrung, communicated with Königsberg. Field-marshal Kalkreuth now arrived in Dantzic, and assumed the command of the place. The next operation of the besiegers was the attack of the isle of Nehrung, which, after a severe and protracted struggle, was carried in the most gallant manner, and measures were immediately taken to secure the 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 Dantzic or on that of Pillau. At this time the governor, who had under his command a garrison of 18,000 men, besides the burgher militia, made a sortie for the purpose of destroying the works of the besiegers; but the attempt failed, and the Prussian columns were smallest success upon any point. compelled to retreat into the place without having obtained the It had been decided that the principal attack should be directed against the fort of Hagelsberg (because the redoubt of Bischopsberg oured by two false attacks, the one directed against the intrenched was more complete and better flanked by the fire of the place), fav camp at Neufahrwasser, and the other against Bischopsberg, and by two secondary attacks on the left bank of the river; and ground was broken on the night of the 1st and 2d April, at the distance of 1600 yards from the palisades. The approaches were 11th the second parallel was commenced by flying sap. On the pushed forward with the greatest vigour, and on the night of the morning of the 12th the batteries were armed, On the 13th the enemy made a sortie in force, attacked the Saxons with great impetuberg, and penetrated even to the head of the trenches; but they osity, carried a redoubt constructed upon the mamelon of Hagelswere 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, from which to throw shells into all quarters of though the garrison returned the fire with the greatest vivacity, by the city. At daybreak on the 23d the batteries were unmasked, and, the 24th the besiegers, firing with 56 heavy guns, had obtained the ascendency, 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 incommoded 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 600 Prussian grenadiers, followed by 200 workmen, sallied out of the place. As the sortie had been foreseen, preparations had been made to repulse it. It was attacked in front and on both flanks; the whole column was either killed or taken prisoners. Meanwhile the works were vigorously pushed forward at all points. The batteries of Stolzenberg were united with the attack on the Bischopsberg; 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 appeared; and the besieged replied by the fire of all the batteries of the front attacked, directing more than thirty pieces on a redoubt which fired with the greatest effect. But rs 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, 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 Chasseloup, who had by this time assumed the direction of the attack, it was decided that the isle of Holm should be assaulted, as the possession of it would enable the besiegers to take in reverse the front attacked. The besieged had spared no pains for the preservation of this important post, from a redoubt on which, called Kalke Schauze, they had continually annoyed the left flank of the trenches. In the night of the 6th and 7th of May, however, it was attacked, and carried after a desperate resistance, whilst the possession of it was secured by works added to the intrenchments which had just been stormed, and its 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 on the 12th a Russian corps d'armee of 18,000 men, under the command of General Kamenskoi arrived by sea, and disembarkedl at the intrenched 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, the third day after the disembarkation, that he made 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 12,000 men, in four columns of attack. The onset was impetuous, and at first the Russians gained ground; but they were ultimately repulsed at all points, and forced to retreat with great loss to the intrenched camp. Field-marshal Kalkreuth made no attempt to second this attack by a general sortie, which would have placed the French between two fires; and by its failure the fate of Dantzic was decided. The works of the besiegers were now pushed forward with redoubled vigour; and 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 driven back, and pursued into the ditch of the place. On the 21st the besieging army 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 Dantzic, who, having no longer hope of succour, and being 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 1793.1 1 See Dumas, Précis des Événemens Militaires, tom. xviii. p. 123. These two sieges illustrate so well the principles of attack and defence, and are so perfect of their kind, that it has not been thought worth while to add an example of a more recent siege; but it should be observed that in future the preliminary operations of the besieger must take place at far greater distances; he will break ground for his first parallel at not less than twice the distance hitherto laid down, and will place his first batteries in rear of the parallel. This, while entailing on him much greater labour in parallels, trenches, and approaches, offers counterbalancing advantages, as it allows him to disperse his batteries in small units without the sacrifice of any of their power of simultaneous concentration on the point of attack, and with diminished exposure to the counterblows of the enemy's artillery. BASTIONED SYSTEMS OF THE NETHERLANDS. The Bastioned System of the Italians was carried into other countries by their engineers, who were extensively engaged in the service of foreign princes, and the celebrated Italian engineer Marchi, coming to Brussels with Margaret of Austria in 1559, appears to have introduced the Bastioned System into the Netherlands. It has been shown that in permanent defences, the ordinary earthen scarp adopted in ditches of field works had been replaced by a masonry revetment as a security against surprise, in consequence of which, in old Italian fortresses, lofty revetments were almost universal; but in a country the soil of which is permeated by water within a few feet of the surface, such a mode of guarding against escalade would have been enormously expensive, and the alternative was adopted of forming broad wet ditches round the ramparts, and by thus securing them from sudden attack, revetment became unnecessary. The first example of a fortress surrounded by simple earthen ramparts without revetments is said to be that of Breda, fortified in 1553 by Count Henry of Nassau, and this arrangement required only to be moulded into the bastioned trace to constitute the ancient system of the Netherlands, as described by Freitag in 1630. Freitag made the flanks of his bastions perpendicular to the curtain, the faces 98 yards long, with a flanked angle not exceeding 90°, and the length of the curtain 149 yards. Freitag had strange notions respecting his profiles, regulating the height and thickness of his ramparts not so much by the resistance they were required to offer to artillery as by the number of sides of his polygon; but disregarding these vagaries of the systematist, the annexed cut (fig. 68) may be assumed to represent the profile usually adopted by the Dutch engineers, R being the body of the place, F the fausse-braye, D the ditch. It will be observed that the main rampart is surrounded by an advanced parapet called a fausse-braye. This advanced parapet was intended to deliver a grazing fire on the ditch, whilst the space between it and the rampart formed a spacious chemin des rondes for the assemblage and movement of troops'; but great as these advantages are, the fausse-braye has dropped into disuse. It is not possible to remain in it under a heavy vertical fire, the shells either dropping directly, or rolling down into it from the slope of the rampart above. Such shell traps, as they are called, are scrupulously avoided by modern engineers, who know that the improvement of vertical fire will ere long add materially to the difficulties of defence. In the bombard. ment of Sweaborg, an illustration was afforded of what may be expected of heavy mortars, when the shell becomes a better representative of a mine than it now is. At present a 13-inch shell weighs, when loaded, 200 pounds, and can carry a charge of 11 b of powder, which is ample for breaking the shell and scattering its fragments, but is insufficient for producing the effects of a mine. The Dutch System of Coehorn deserves especial attention, and is represented in Plate IV., fig. 1, which exhibits his first system. The great characteristic in this system is the combination of wet and dry ditches, and the use of covering A works, or couvre-faces, intended to preserve the body of the place from injury till an advanced period of the siege. These envelopes were first proposed by Dürer, and it is worthy of note that the remarkable orillon of Coehorn is a reproduction on a modern scale of the complicated casemated structure of one of Dürer's basteien. Coehorn was well acquainted with the principles and the systems of the eminent German engineer Speckle, and adopted them when applicable to his purpose. The profile (fig. 69) may enable 10' 8° B FIG. 69.-Profile of Coehorn's Bastion-A, inner or upper bastion; B, outer or lower bastion; D1, dry ditch between the two; D3, wet ditch. the student to appreciate the difference between the dry | ditches of Coehorn and the narrow passage afforded by the fausse-braye of the older engineers. The profile exhibits also the loopholed galleries of the counterscarp, by which a reverse musketry fire is directed on the revetted escarp of the inner rampart,-a system of defence which has since been generally adopted, and is most valuable when a secure communication can be kept up between the galleries and the work which they are intended to defend. After the great siege of Corfu by the Turks, and its successful defence by Schullemburg, some Dutch engineers who had been invited to Corfu by him, and had taken part in the defence, were employed in adding detached forts to the old Italian bastioned fronts. In these works the ruins of numerous examples of loopholed galleries and loopholed traverses may be observed; and they demonstrate that though Coehorn adopted in his writings his reliefs to the aquatic sites of Holland, he developed principles of defence which were equally applicable to other sites and other countries. It has been argued by Bousmard and others that an opening would be formed by shells through the couvre-face, and that the flanks of the bastions would be thereby exposed to the fire of the counter batteries on the glacis; but it remains to be proved whether such an opening through an earthen mass could really be effected by the horizontal fire of shells; and the French translator of Zastrow, M. Neuens, captain of artillery, justly remarks that, "if shells fired horizontally into earthen works are so efficacious in destroying them, such shells must be a still more powerful instrument in the hands of the defenders for destroying the besiegers' batteries." Zastrow observes that, if we admit with Coehorn and others that, though the besieger may succeed in destroying a few feet of the parapet of the lower or outer face of the bastion, he would in vain, by firing shells horizontally into its mass, endeavour to lay open the counterscarp galleries, it must be admitted that he would, on mounting the low face, find himself in a most critical position, as all the defences, both direct and reverse, of the dry ditch, would remain uninjured, and be in full action against him. These dry or inner ditches, which facilitate the war of sorties, and the reverse or counterscarp galleries, are defensive arrangements of great merit, and may, by modification of profile, be adapted to any site; though the advantage dry ditches offer in such countries as Holland, where the besiegers cannot excavate in them with out coming to water, cannot be expected in other sites, and must be made up for by stone pavements, or other contrivances likely to embarrass the besieger in his excavation. | Coehorn assumes the plane of site to be 4 feet above the level of the water, and the dry ditch of his bastion is at its centre on the level of the water, so that a passage by sap becomes impossible, as the spade sinks at once into water; but near the escarp and counterscarp the ditches are 24 feet below the plane of site sloping on each side towards the central portion. The breadth of the dry ditch of the bastion is 98 feet, and that of the wet ditch before the salient 148 feet. All the slopes are at an angle of 45°. The whole breadth or thickness of the couvre-face, measured at the water level, is 52 feet, so as not to afford space for the besiegers' batteries, and its relief of construction only 12 feet. In the ravelin the relief of the low face is 10 feet, of the high face 18 feet, and the height of its revetment 8 feet; in this work also the thickness of the low face would not afford space for batteries. The width of the dry ditch is the same as that of the bastion. These few details, with an examination of Plate IV., and of woodcut 69, will enable the student to comprehend the general principles of this great engineer; and it is rather by tracing out the ideas of a master mind, as exhibited in the peculiarities of his plans, than by studying the plans themselves as wholes, that the engineer will acquire practical knowledge which will enable him to vary his own projects, so that they may really be the best suited for the ground he is working upon. Cochorn never restricted himself to the rules even of his own system. In fortifying Gröningen he was required to construct works on an eminence which commanded the town and he adopted a trace towards the exterior of tenailles, the gorges of which were closed by small bastioned fronts constructed by walls which should be easily breached from the main works when the enemy bad succeeded in gaining possession of any one of the intervening redans. By this curious combination of the tenaille and bastioned systems, Coehorn gave an undoubted proof of his superiority to the narrow prejudices which often prevent the adoption of the system best suited for the place. METHODS OF BOUSMARD, CARNOT, CHASSELoup, Durour, It would be wrong to dismiss the subject of Bastioned Systems without at least some more reference to the works of these distinguished engineers than has been given in tracing the history of this subject. Bousmard makes the faces of his bastions as well as their flanks curvilinear, the former convex, and the latter concave outwards; but though by this arrangement the effect of ricochet fire may be dim inished, the difficulty of defending the salient from the flanks is much increased. His great innovation, however, consisted in placing the ravelin and its redoubt in advance of the glacis of the body of the place, and forming in front of them a second or advanced covered-way, the object being to close the main ditch entirely, so that the besiegers' batteries should not he able to fire upon the body of the place through the ditch of the ravelin. The covered-way is made en cremaillére, and at each bend there is a sort of redoubt, or casemated traverse, not a simple hollow traverse loopholed, such as those in the detached works of Corfu. It has been objected to Bousmard's system that his advanced works would be speedily taken by turning the gorges both of the ravelin and its redoubt, but it should be remembered that the interior slope of both is replaced by a loopholed wall, being the front of an arched gallery running all round, so that the enemy could not remain within these works exposed to the fire from the galleries, as well as from the body of the place. Without advocating the precise form and disposition of the works recommended by Bousmard, it may be reasonably asserted that in every case of a powerful and well-appointed garrison, the defence will gain by assuming an active character beyond the precincts of the glacis. Chasseloup (1754-1835), like Bousmard, placed his ravelin in advance of the glacis, and provided it with a small casemated keep, the flanks of which are pierced for two guns each. The tenaille is also provided with casemated flanks, and in front of it is a casemated redoubt or bastionette to supply the place of the ordinary ravelin, and to flank the salient portion of the face of the bastion, the general face being by him bent into two, so as to place the salient portion in line with the exterior side of the polygon, and thereby secure it from the ricochet fife. Casemated redoubts in the re-entering and salient places of arms, a defensive barrack, and a permanent entrenchment on the bastion are also included in his arrangements. Do Sellon (Mémorial de L'Ingénieur Militaire) observes, "It would indeed be well to force the besieger to pass through two sieges, if the outworks pushed so far forward: had higher scarps, and were not so easily turned at the gorge, but as the scarp is only 13 feet high, this possibility of attacking the works by the gorge without a previous descont into the ditch presents such serious inconveniences that it is surprising to observe that Bousmard and Chasseloup should have adopted so defective an arrangement." But notwithstanding this strong condemnation, it is at least doubtful whether such works are not the most suitable for a vigorous defence by a strong garrison, as they would enable the besieged to fall upon the assailants at the most critical moment of their attack with a powerful force; and it may be added that a skilful engineer would know how to throw many difficulties in the way of turning these advanced works, whilst the continuance of the besiegers in them might be rendered both difficult and dangerous in the extreme. The most remarkable feature in Dufour's modification of the modern system is, that one face of tho redoubt in the re-entering place of arms is carried across the ditch, and connected with the coupure of the ravelin, so as completely to close the ditch and cover the face of the bastion from the fire of a battery on the glacis of the salient of the ravelin. Dufour also raised the salient of the ravelin into a high cavalier, so as to secure the faces from ricochet; and he proposed that the cavalier should be formed of gravel or small stones, so that the fire from the body of the placo might, by scattering about these natural missiles, cause great damage to the enemy, when attempting to form a lodgment. As already observed, an unmerited indifference nas been manifested by many engineers to the merits of Carnot, principally, it may be believed, from his exaggerated estimate of the 'effects of vertical fire of small-projectiles. Although he appealed to imagination rather than to calculation, when he assumed that by substituting 600 wrought iron balls, weighing each b, for the one shell of 150 tb, with 6 mortars projecting 3600 balls, he might expect to put hors de combat 20 men at each discharge, or 2000 in 100 discharges, he was right in urging the importance of vertical fire. Carnot constructed his escarp without a revetment, but placed a detached loopholed wall in frontof it with a chemin des rondes between, which is one essential feature of his system, the wall being constructed with arched niches in rear so as to shelter the men defending it; the loopholes are in two rows. He provided arched casemates for mortars on the gorge of his bastion in order to fire upon the capital, and the loopholed wall of an inner curtain, being continued along the retired flanks and in front of these mortar casemates, formed a complete inner retrenchment. Between the tenaille and the ravelin was an earthen cavalier, occupying the position of a redoubt in the ravelin, before General Noizet has been already mentioned in connexion the bastion's counterguard, so that the whole of the interior with the Modern System, his modification of which is now works were masked by these earthen envelopes. There is the normal system adopted at the French military schools. much ingenuity in these arrangements, and at least as full Rejecting Dufour's mode of closing the ditch of the ravelin an appreciation of the value of earthen works as can be by carrying across it one face of the redoubt of the re-enterfound in the writings of any modern writer. Carnot's leading place of arms, he effected the same object by placing a ing principle, however, was, that a successful defence must massive mask between the coupure of the ravelin and the depend on the active operations of the garrison, and that re-entering place of arms, from the inner escarp of which it sorties therefore should be frequent and determined as soon is separated by a passage. The counterscarp of the bastion as the enemy had approached close to the fortress. For is carried continuously along the inner edge of the mask, this purpose ho removed the revetment from the counter- whilst in front of it is a ditch which separates it from a scarp, and formed it into an easy or countersloping glacis, demi-caponnière forming its counterscarp and covered-way, to admit of the ready advance of the troops from the ditch and a glacis sloping down the ravelin of the ditch. The upon the head of the besiegers' sap. He supposed that the mask, the lunette redoubt in the ravelin, and the redoubt overwhelming vertical fire of the 10 mortars in the mortar in the re-entering place of arms form a combined series batteries in the gorges of his bastions would prevent the of works of great efficiency for defence, which completely enemy from accumulating large covering parties in the cover all but the salient portion of the face of the bastion. trenches, and that he should therefore be able to fall upon The flank of the bastion, as before observed, forms an angle the working parties and successfully delay the progress of of 80 with the line of defence, and the advantage taken of the works. It has been shown that Carnot entertained an this in the citadel of Ghent in forming a most powerful inexaggerated view of the effects of vertical fire, but the idea trenchment in the bastion, with a curtain as long as that of of securing his mortars in casemated buildings is good, and the main front, has also been pointed out. has been adopted in the citadel of Ghent, and in several English works at Portsmouth and Plymouth; and it is impossible to study his works without profit. General Haxo, one of the ablest engineers of modern times, did not publish his scheme of defence, nor did he reproduce it as a whole in the works be constructed, doubt |