World War II Tunnels, Gibraltar

During the Second World War, Gibraltar witnessed the most extensive phase of tunneling in its history, playing a crucial role in the North Atlantic and Mediterranean arenas. The war prompted a substantial increase in the length of tunnels, expanding from 7 miles (11 km) to 25 miles (40 km).

At the war's outset, the civilian population was evacuated, and the garrison size was significantly augmented. Numerous fresh tunnels were excavated to accommodate the expanded garrison and store vast quantities of provisions, equipment, and ammunition. This tunneling endeavor was undertaken by four specialized tunneling companies from the Royal Engineers and the Canadian Army.

A new Main Base Area was established in the southeastern part of Gibraltar, along the Mediterranean coast of the peninsula. This location protected the potentially hostile Spanish mainland while connecting tunnels were constructed to link it with the existing military bases on the western side. Two tunnels, known as the Great North Road and the Foss Way, were painstakingly dug, spanning nearly the entire length of the Rock, interconnecting the majority of the wartime tunnels.

The tunnels served as an underground city, capable of accommodating the entire 16,000-strong garrison and storing enough food to sustain them for 16 months. Within this subterranean complex, various facilities were established, including an underground telephone exchange, a power generating station, a water distillation plant, a hospital, a bakery, ammunition storage areas, and a vehicle maintenance workshop.