From GibMap
The labyrinth of tunnels inside the Rock, including these, is arguably the most impressive defence system designed by humans. During the American War of independence, when France and Spain made an attempt to recapture the Rock from the British in Gibraltar's 14th Siege (always called the Great Siege) which lasted from 1779 to 1783, Governor General Augustus Elliot offered a reward to anyone who could tell him how to get guns onto the precipitous northern face of the Rock. Sergeant Major Ince suggested tunnelling, and, in gratitude, was given a Commission and a plot of land on the Upper Rock (still known today as
Ince's Farm).
See web-site
