30 SIEGE with steps on the inner side to allow a detach- ment of picked men to sally out at a given sig- nal with a front equal to that of the assaulting column. They are preceded by engineer offi- cers, who mark out the lines for a trench four or five yards from the crest of the glacis, and extending around the salient place of arms, and are followed by a detachment of engineer troops to construct it. When everything is in readiness, all the batteries open fire on the place. At a given signal they cease, and the column of assault rushes forward and takes poiiession of the covered way. The engineers immediately make the sap, into which the troops retire if successful, and afterward con- nect it by suitable communications with the third parallel. The execution of this trench around the salient place of arms is called crown- ing the covered way. In 1708, at the siege of Lille, the covered ways of two of the salients of the front of attack were crowned by assault. The attack was made at nightfall by 10,450 men, not counting the troops in the trench- y lost 2,000 killed and 4,000 wounded. The best engineering authorities are opposed to an assault except in case of urgent necessity, when a day gained may decide the fate of the besiegers themselves, or the time saved by it compensates for the immense loss of life that must accompany it. If the advance is to be made by regular approaches, they are started he third parallel by saps, which when within 30 yards of the salient are spread out in a circular form to enclose it, and high mounds of earth, called trench cavaliers, are thrown up, by which a command over the covered way is obtained. Protected by them, the engineers advance their saps to the salients and extend them to the right and left along the faces, at least as far as the traverses, as in the case when the assault was made. As soon as this is done, they proceed to establish coun- ter and broaching batteries to fire against the demilune and bastion. The former are placed around the salients so as to fire in the direction of the ditches against the portion of the work by which they are swept, while the latter are placed near the counter batteries and nearly opposite to the points where the breaches are to be made. Underground galleries are also acted, by means of which a descent into the ditch can be effected. A breach is con- sidered practicable for assault when the in- terior of the work is exposed for a width equal front of the column of attack and the forms a slope of easy ascent. If breaches ore to be made at several points, the operations should be carried on and the assaults made simultaneously. The breach in the demilune will l.o rurriM by assault or by regular ap- proach, and in all essential things there will be ' rvrxv in the mode of taking it from that describe.! f -r the covered way. As soon as the breach is gained, it is crowned, or a lodgment made by encircling it with a trench in which troops are placed to prevent the besieged from SIEGEN regaining possession of the work. The demi- lune being taken, advances are made against the reentrant places of arms and salient of the covered way of the bastion, if they have not already been crowned. Other batteries are established against the faces and flanks of the bastion, and operations similar to those already described affe carried on against the main work. A capitulation will ordinarily follow the crown- ing of the breach in the bastion, unless there are interior retrenchments, in which case the same method of attack will be followed until there is no longer any defence between the besieger and besieged. The breaches are sup- posed to have been made by battering the ram- parts with artillery fire. The other method is by means of mines, which are rarely used be- cause of the slowness of the operation and the uncertainty of the result. The explosion of the mine gives no practicable slope for the use of the assaulting column, and this must be made by workmen before it can be used, which is very difficult and dangerous. To resist the approach of the besiegers, the defence make use of mines ; to destroy these, and to advance their works, the besiegers also employ them. They will be most largely used between the third parallel and the main work. The passage of the ditch is a difficult and dangerous opera- tion, rendered doubly so when the besieged have a wet ditch, or can make use of water in their defence. In an actual siege, a daily rec- ord is made by the engineers of the amount of work done and the time required, which is transmitted to headquarters and preserved. By comparisons of these records and the re- sults obtained in engineering schools, the time necessary to complete all these works has been calculated. This time has been used in comparing the relative value of different sys- tems or methods of fortification, by submitting them to a fictitious siege. It is of no value in practice, for the duration of sieges depends on laws which no method of calculation can de- termine. In order that the besiegers should be successful, their numbers and their arma- ment should be in excess of those brought to resist them, and no fixed rules can be stated for this excess. As a general rule, supposing the investment to be complete, the besiegers should be about six times as numerous as the besieged, and should be kept so by sending the wounded and sick to the rear and replacing them by fresh troops. As the defence have not this resource, their numbers constantly dwindle until they are exhausted or overpow- ered. Among the most celebrated sieges in history are those of Babylon, Tyre, Syracuse, Carthage, Numantia, and Jerusalem in ancient times, and of Constantinople, Antwerp, Ber- gen-op-Zoom, Stralsund, Candia, Lille, Buda, Schweidnitz, Saragossa, Sebastopol, Vicksburg, Strasburg, Metz, and Paris since the introduc- tion of gunpowder. SIEOE.V, a town of Prussia, in the province of Westphalia, on the Sieg, 37 m. S. of Arns-
