Tunnelling Companies Royal Engineers in World War II: excavation of bomb-proof facilities in France, Gibraltar, Malta and the UK

170 Tunnelling Company Royal Engineers left England in January 1940 to excavate bomb-proof military headquarters in northern France. Expansion into companies 170, 171, 172 and 173 was delayed when the British Expeditionary Force was defeated and evacuated, but completed in England in July to excavate accommodation underground for regional headquarters and artillery batteries – mostly in Cretaceous chalk. Companies 178, 179 and 180 formed in England in May–June 1940, and 178 and 180 soon deployed to Gibraltar, joined by 170 in 1941 and successively by 1st and 2nd Tunnelling Companies Royal Canadian Engineers. They excavated a major complex of tunnels and chambers within Jurassic dolomitic limestone by October 1943 to help fortify the rocky peninsula, work completed by a single company (172) thereafter. Companies 183, 184 and 185 joined 179 in 1941 to emplace ‘Canadian pipe mines’ to inhibit the invasion of Britain. 173 served in Malta 1941–43, and 171 during 1943–45, excavating >50 bomb-proof facilities in Oligo-Miocene limestones, plus works to enhance the civilian water supply. By late 1943, all companies except 172 (Gibraltar) and 171 (Malta) were based in Britain. At least five were converted for general engineering use and no longer needed geological assistance.