The Rock of Gibraltar is the key to the entrance to the Mediterranean Sea from the Atlantic Ocean. Thrusting 1300 feet above the Spanish plain on the Bay of Algeciras, the Rock of Gibraltar has been a great British fortress and an important defensive outpost since its acquisition in 1704. Through the years the Royal Engineers had excavated tunnels and galleries in the rock for defensive purposes.
During World War II Gibraltar was a major naval and air base. It became a vital strong point upon the fall of France and the entry of Italy into the war since the Germans were on the Spanish border and the Italian fleet was poised in the East. Two Royal Engineer Tunnelling Companies were dispatched to Gibraltar in 1940.
A tremendous amount excavation was required to improve the defences at Gibraltar and the expertise of the Canadian tunnellers was sought. The Canadians were in particular demand as many were hard rock miners, a somewhat uncommon trade in the United Kingdom. In response, Canada first sent a special detachment of No. 1 Canadian Tunnelling Company, which was then operating in England. This detachment commenced work on 26 November 1940.
By the end of that year it was appreciated the work was greater than had been anticipated and the War Office requested that the remainder of No. 1 Tunnelling Company be sent to Gibraltar. However, No. 1 Canadian Tunnelling Company was fully committed in England so it was decided to mobilize a second tunnelling company for work in Gibraltar. An additional detachment of diamond drillers and additional equipment from No. 1 Tunneling Company RCE arrived in Gibraltar on 12 November 1940 and No. 2 Tunneling Company joined them early in 1941.
The Canadians worked on excavating a series of wards and tunnels to make a hospital area inside the Rock. The largest chamber was 200' x 35' and 12' high. They also constructed ammunition magazines, oil storage tanks, pillbox fortifications and installed heavy timbering where rock conditions required it. A quarrying operation produced fill to extend the airfield runways. During their two years on The Rock, 234 Canadian men and officers mined and removed about 140,000 tons of solid rock as well as putting in 46,000 man hours on construction work. The Canadian tunnellers produced 35 cubic feet of excavation per man per shift on average. This production rate exceeded that achieved by civilian mining operations. In later stages, this production rate was increased when mechanical equipment became available to remove muck from the tunnel face.
Most importantly, the Royal Canadian Engineers had contributed immensely to the war in the Mediterranean by helping to construct the defensive works at Gibraltar.