10. The British counterattacked at Gibraltar
By the late autumn of 1781 supplies at Gibraltar were again dwindling, and the garrison discovered from Spanish deserters that the Spanish were preparing an assault for the ever advancing siege lines. On the night of November 27, 1781, the British launched an assault of their own, sallying forth with an attack of just over 2,500 men which caught the Spanish completely off guard. The advance posts of the Spanish siege works were captured, along with supplies, gunpowder, mortar shells, and artillery. The British wrecked the fortifications, spiked the guns, burned the supplies which they could not carry, and then withdrew into their own fortifications. The Spanish had over 100 casualties, the British five.
The British November sortie threw the Spanish timetable for the reduction of the Gibraltar garrison into a shambles. The assault they had been planning was postponed indefinitely as the Spanish and French troops rebuilt their fortifications and continued the bombardment of the British positions. The British meanwhile began the construction of a system of tunnels in the Rock of Gibraltar which allowed for the placement of guns capable of depressing their aim, allowing them to shoot down at troops approaching the Rock as well as elevating the barrel to engage targets at a distance. In March the British garrison at Minorca finally surrendered to the French, and French troops from the Minorca siege joined the Spanish besieging Gibraltar.