BREACH, in siege-works, is a gap in any of the defensive walls or gates of a city; and breaching is the operation by which the gap is produced by the guns of the besieg ers. Breaching batteries are employed, consisting of several pieces of ordnance, so chosen as to kind and size, and so placed as to distance, as to burst a hole through the defenses in the shortest practicable time. The greatest effect is produced by lodging the balls in two vertical lines, from the parapet of the wall downwards, and in a hod zontal line, connecting the lower ends of those vertical lines; and then overturning the mass of material thus loosened by an irresistible salvo or volley. When a hole has once been made, by ,thus knocking away the masonry or earthwork, the breaching is con tinued until the crumbling mass has so accumulated as to form a practicable slope, up which the storming-party of the besiegers may run. See ASSAULT. During the Penin
sular war there were some formidable examples of breaching. At Badajoz, 14,000 shot brought down 180 ft. of wall in 104 hours, from a distance of 450 yards. At Ciudad Rodrigo, 6700 balls brought down 105 ft. of wall in 32 hours, from a distance of 360 yards. At St. Sebastian, 13,000 shot brought down 100 ft. of wall in 62 days, front a distance of 620 yards. It was calculated, from these and other instances, that 10,000 24-lb. shot, or 240,000 lbs. of iron, will breach 100 ft. of wall from a distance of 500 yards —the wall being of fair average masonry, and the height and thickness a fair average of those used in fortified towns. It must be remembered, however, that this estimate was made before the days of rifled cannon and Armstrong guns; and, on the other hand, that the walls adverted to were not constructed of granite.