Date: Dec, 2014
Location: Upper Rock, Gibraltar, UK
The Great Siege Tunnels were dug out by hand, mainly using sledgehammers and crowbars, aided by gunpowder blasts, from the solid limestone by the British during the Great Siege of Gibraltar at the end of the 18th century.
The Great Siege was an attempt by France and Spain to capture Gibraltar from Great Britain during the American Revolutionary War. It was the fourteenth and final siege of Gibraltar, from July 1779 to February 1783. During the siege, British and Spanish forces faced each other across an approximately 0.62 mi wide isthmus immediately to the north of the Rock of Gibraltar. The British lines blocked access to the City and the western side of the island, while the eastern side was inaccessible because of its steep terrain. Guns were placed in a series of batteries on the north face of The Rock, providing overlapping fields of fire.
The construction of the tunnels came from the garrison’s need to cover a blind angle on the north-east side of The Rock. The only solution found to cover that angle was via a gun mounted on a spur of rock known as The Notch. There was no possibility of building a path there due to the vertical cliff face, so Sergeant-Major Henry Ince of the Military Artificers suggested digging a tunnel to reach it.
WWII led to another great wave of tunneling as work was undertaken to enable The Rock to house a garrison of 16,000 men with water, food, ammunition and fuel supplies sufficient to last a year under siege. The Great Siege Tunnels were reused during the war; although it is uncertain exactly how they were used, it appears that they may have housed one of the generators used to power Gibraltar’s searchlights. The Great Siege Tunnels were extended in two directions during the war, with a long straight extension called the Holyland Tunnel continuing through to the east side of The Rock, so named because it points in the direction of Jerusalem, and a staircase dug to link the tunnels with other World War II tunnels below. However, the methods by which the WWII tunnels were hastily excavated have meant that, unlike the original 18th century tunnels, they have crumbled rapidly and now can not be accessed safely.