Failing to obtain the submission of the garrison either by famine or bombardment, the enemy attempted to mine a cave in the rock, by which to blow up the north front, and thus make a breach for their easy entrance into the fortress. The secret was revealed by a deserter; but very little attention was paid to his statement, until the discovery of the enemy’s proceedings was made by Sergeant Thomas Jackson, who, making a perilous descent of the rock by the help of ropes and ladders, ascertained beyond all doubt the work in which the Spaniards were engaged. The ratification of peace put an end to all military operations, and terminated a siege which extended—with circumstances of unparalleled difficulty and danger—over a period of four years. During the whole of this memorable defence, the Company of Artificers proved themselves to be good and brave soldiers, and no less conspicuous for their skill, usefulness, and zeal in the works—works, as the commander of the hostile forces [Duc de Crillon] remarked, “worthy of the Romans.” At the close of the siege, there were twenty-nine rank and file wanting to complete the number of Soldier Artificers. The deficiency was speedily supplied, and the company was never allowed to sink beneath its established number. A force of more than two hundred and twenty non-commissioned officers and artificers were employed in restoring the work which had suffered during the bombardment; and to expedite the labour, the Soldier Artisans were excused from all garrison routine, as well as from their own regimental guard and routine, and freed from all interference likely to interrupt them in the performance of their working duties. Still, to impress them with the recollection that their civil employments and privileges did not make them any the less soldiers, they were paraded, generally under arms, on Sundays; and to heighten the effect of their military appearance, wore accoutrements which had belonged to a disbanded Newfoundland regiment, purchased for them at the economical outlay of seven shillings a set. Perhaps no body of men subject to the articles of war were ever permitted to live and work under a milder surveillance; and it may be added, that none could have rendered service more in keeping with the indulgences bestowed. In the summer of 1786 the company was divided into two, the chief engineer still continuing in command of both companies. About the same time, those men who were disqualified in any way for service were removed from the corps, and the enlistment of _labourers_, in addition to skilled hands, was authorized by the Government. Five batches of recruits were sent to the Rock in rapid succession. The second party of recruits, comprising fifty-eight men, twenty-eight women, and twelve children, were destroyed in a storm off Dunkirk. Only three persons escaped.