FORTIFICATION. 



then filled up with rubbish, either loose 

 or in bags, &c. so that they are no longer 

 passable. 



The nakedness opposite the angle B, 

 of bastion 3, is left purposely, to shew 

 how easily a besieging army would effect 

 a breach at that angle, provided no addi- 

 tional outworks were supplied ; for, as 

 yet, we are to consider the fortress to 

 consist only of the principal and the ra- 

 velines. A suitable train of battering 

 cannon brought to act upon the point B, 

 while other batteries were employed to 

 silence the faces of the adjacent rave- 

 lines O and N, would, in a very few days, 

 effect a breach, and give the besiegers a 

 command of the ditch, by establishing 

 themselves in a lodgment on the crest of 

 the glacis g, at the saliant point q; 

 whence they would batter the flanks 

 o S, and TV v. Then, as nothing could 

 oppose their passage over, the ditch, 

 which if wet would be passed by sap, 

 (i. e. by filling up with fascines, &.c.) 

 the angle B would be carried by storm : 

 for the matter would obviously rest on 

 the numbers, and on the personal prow- 

 ess of the contending forces. The issue 

 of such affairs have been so various, that 

 it would be presumption to say the be- 

 siegers must succeed ; but if the breach 

 be practicable, and the internal state of 

 the bastion, as seen in No. 3, even though 

 there should be an intrenchment of 

 the gorge, i. e. from r to it, the chances 

 would be in their favour, after the breach 

 was gained. This mode of defence is 

 perhaps the best in hollow bastions ; 

 that is, in such as are not solid, but 

 have deep areas within them, level with 

 the streets of the town, &c. (called the 

 terre-pleine ;) but in a solid bastion, some 

 defences should be internally constructed 

 while the breach is making 1 ; of this some 

 idea may be formed by the flanked angle 

 in bastion 4, where a rampart and ditch 

 are made, to force those who may as- 

 cend the breach to quit the bastion. 

 The gorge may also be fortified as in 

 bastion 3, whereby much time may be 

 gained, a matter often of the utmost im- 

 portance, either from the expectation of 

 succours, or to favour the evacuation of 

 the fortress altogether. 



In bastions No. 3 and 4, the flanks t u, 

 and iv v, are not only curved, but they 

 are double, presenting, of course, two 

 tiers of cannon, of which the upper stand 

 on the bastion, while the lower are just 

 below the level of the berm, whereof they 

 constitute a part, and cannot be discover- 

 ed beyond the crest of the glacis. These 



latter, therefore, cannot be battered from 

 the approaches in the early stages of a 

 siege : they lay, as it were, perdue, in 

 reserve for the defence of the ditch. 

 There are two little semi-circular projec- 

 tions at t and w, called orillons ; these 

 serve not only to cover the flanks t u and 

 w <v from enfilade, but each mounts a 

 gun which cannot be perceived until half 

 way over the bridge, and which serve to 

 defend the gate when assaulted, as well 

 as to take the assailants in flank, and 

 partly in reverse, (*. e. from behind,) as 

 they advance to the attack. 'I hey are 

 especially useful when a tenaille, as seen 

 at P, is constructed in the dry ditch be- 

 fore the curtain S r; for when those who 

 were placed in the tenailles, which com- 

 mand the interior of the raveline O, and 

 of the redoubt Q, may be attacked in 

 flank, and be obliged to retreat into the 

 principal, along the caponnaire P A f 

 these guns pour in grape a.long the inte- 

 rior of the tenaille, when it is in the hands 

 of the enemy, and enfilade so as to cause 

 its abandonment. 



The caponnaire is a passage made be- 

 tween two parapets, each having a long 

 talus, or slope, outwards ; as expressed 

 by the small lines diverging from the 

 path. It is commanded by (*'. e. open to 

 the fire) the flanks o s, and s r, and the 

 centre of the curtain s r. Demi-capon- 

 naires are common for the passage of 

 troops from one outwork to another, as 

 seen at e e, in the raveline N, where they 

 serve to shelter the narrow defiles lead- 

 ing into the intrenchmehtsjf/J within the 

 crown-work M. They have but one pa- 

 rapet, which is open to the fire of the 

 faces B t, and iv c, also to the oblique fire 

 of the curtain between n&ndv. By their 

 exterior slope they serve to flank tne pas- 

 sage of the ditch of the raveline, in con- 

 junction with the faces B t, and C w, 

 which fire over them, and command the 

 whole interior of the horn-work M. 



Having established, by this exposition, 

 the absolute necessity for adding exteri- 

 orly to the defence of the principal, we 

 shall now proceed to give a general in- 

 sight into the various modes of construct- 

 ing the other outworks ; all being so de- 

 signated, which do not come within the 

 principal or body of the place. The read- 

 er should understand, that every outwork, 

 as it is placed more distantfrom the prin- 

 cipal, must have a less elevation from the 

 terre-pleine, or level of the area, on 

 which the walls of the principal are found- 

 ed. Thus we find, that aline drawn frpm 



