ATTACK AND DEFENCE. 163 



seloup has protected all parts of the enceinte where breaches can be estab- 

 lished by vaulted buttresses and magistral galleries. To prevent the enemy 

 from making the passage of the ditch in the direction of the breach 

 towards the faces, Chasseloup has provided the great bastions with the 

 cavaliers, C, which must be separately taken. The elevated casemates, A, 

 first become effective when these cavaliers are attacked, and in conse- 

 quence of this fire and that from the cavalier, c\ the enemy is compelled to 

 make a lodgment on the breach, which is swept from c^ ; c\ with the case- 

 mate, g, supports c^ and covers the exit h. At e are bomb-proof sheds, for 

 the pieces from c" when not in use ; / are vaulted casernes for the protec- 

 tion of the ditch and of the exit. PL 48, fig. 28, shows a profile along the 

 lin§, N O, through the main enceinte and the tenaille. Figs. 26 and 27 

 show two profiles, along the lines G H and KI, of the redoubt of the demi- 

 lune, and^^. 29 a profile along the line, L M, of the redoubt of the places- 

 of-arms of the covered- way and the attacked traverses. Alessandria in 

 Italy is fortified upon Chasseloup's system. 



F. ATTACK AND DEFENCE OF FORTIFIED PLACES. 



In ancient times, when the art of fortification was yet in its infancy and 

 when all siege engines were exceedingly ineflicient, a siege was a most 

 tedious affair ; instances are not wanting where one has lasted even for many 

 years. A cursory survey of the ancient method of carrying on a siege 

 may here precede our passage to modern times. The fortification to be 

 besieged was shut in on all sides, to cut off its communications and means 

 of subsistence ; for this purpose it was surrounded with double walls of cir- 

 cumvallation, between which the besieging army encamped, and by means 

 of which it was defended, as well from the assaults of the garrison as from 

 exterior attacks. PL 41, fig. 2, shows the circumvallation which Scipio 

 established when he besieged the city of Numantia, secured by its position 

 upon a mountain from storm. If, on the contrary, a fortress was to be 

 stormed, it was then approached, much as at the present time, by means of 

 trenches. Fig. 3 gives a representation of Caesar's siege of Massilia ; here 

 stone siege towers (pL S5, fig. 2) were first built, which served at once for 

 guard and watch towers and for casernes. From these the fortress was 

 gradually approached by means of covered communications (fig. 7 A), and 

 with palisades and mounds of earth (B), a parallel was established as at 

 present. The ditch being attained the tortoises (C) went forward, by 

 means of which the ditch was filled up and a dike constructed for bringing 

 up not only the battering-ram but the movable siege towers to the foot of 

 the wall, and for the passage of the besiegers to the assault of the breach. 

 All works were carried on, before the completion of the galleries of commu- 

 nication and the parallel, under cover of the movable screens, DD. In the 

 Middle Ages also this method of siege was practised, but then many subter- 

 ranean galleries were wrought, which must have been of great dimensions, 

 for we know that in the fifteenth century single combats on horseback were 



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