MINES, MILITARY, are excavations made in the rampart of a fortress, or underground, in order to contain gunpowder, which, being exploded, the rampart may he breached, or any works of the enemy, above or near the mine, may be destroyed.
The term offensive is applied to the mines which are formed by the besiegers of a fortified place ; those which are formed by the garrison are called defensive mines, or counter-mines, this term having been given to the mines executed by the besieged, as they were the latest introduced in warfare. The cavity in which the powder is deposited is called the chamber; and the excavated approach to the latter is called the gallery, if the dimensions are above 3 feet by 4 feet ; if smaller than this, a branch. These are termed ascending or descending, according to their direction, though if they are vertical they are termed shafts.
Two kinds of mines were anciently employed in the attack of fortresses. One of them was merely a subterranean passage carried under the walls from the exterior ground ; and being suddenly opened within the town, the assailants were enabled to enter the latter by surprise. The other kind was executed in a similar manner, and was intended to lay the rampart of the place in ruins; fur this purpose, the gallery, having been driven as far as the walls, was carried on to the right and left under the Litter, which were supported by preps of timber till the time appointed for the assault was come ; then, the props being drawn away or consumed by fire, a portion of the rampart fell into the ditch ; and the troops, who were kept in readiness, passed over the ruins into the town. Mines of this kind are described in a relation of the siege of the castle of Bones near Amiens, at which siege Philip Augustus attended in person. At the siege of Melnn, which was carried on by henry V., king of England, and the Duke of Burgundy, in the year 1420, the besiegers having driven their mine almost up to the walla, and the besieged having executed a mine in opposition, a barrier was erected where the two galleries met, and there the king and duke fought with lances against two Dauphinais.
As the parties engaged two abreast, it is evident that the galleries must have been a considerable breadth. The old French writers occa sionally applied the term mines to what were also then, and are now, called trenches. Thus, at the siege of Hartieur, in 1449, mention is
made of broad and deep trenches by which the approach to the wall is said to have been rendered secure; and the same works arc immediately afterwards called mines.
Gunpowder was, in 14S7, used in military mining by the Genoese at the siege of Serezanella, a town belonging to the Florentines; but on this occasion without success. It is stated, however, in the life of Connive, do Cordova, that Peter of Navarre, a Spanish engineer, formed mines with gunpowder at the siege of Cephalonia, near the end of the 15th century, when the Venetians and Spaniards took the island from the Turks. And in 1503 the same engineer, or, according to Valliere, an Italian called Francis George, succeeded in taking by such a mine the Castle del' Ovo at Naples. This fortress was situated on a rock nearly surrounded by the sea, and had during three years resisted the united arms of the Spaniards and Neapolitans. From that time the prac tice of forming mines with gunpowder was almost constantly followed in the attack, and after a short time gradually in the defence of fortresses. So powerful was the effect of mines in the attack, that it was not an unusual occurrence for the besiegers after forming their mine to invite the besieged to see it, in order to bring about a surrender with out further bloodshed. The besieged from very early times had a gallery placed a short way in advance of the foot of the wall, termed an envelope gallery, to warn them of the operations of the besiegers. From this gallery branches were run out, and used to what was termed "give the camoullet to the enemy's miners; " that is, a small charge was exploded, which, though insufficient to produce any surface effect, destroyed the besieger's gallery and suffocated his miners. From this to the adoption of ordinary mines was a small step. By means of 1173 mines, great and small, the Venetians defended Candia during more than two years (1666 to 1669) against the whole power of the Turks. By mines also, in 1762, the town of Schweidnitz was defended during 63 days by the Austrians against the Prussians. In the course of this last siege two of the mines fired by the besiegers had charges of powder amounting to 5000 lbs. each ; and the depth of the charge below the surface of the ground was from 18 to 20 feet.