In 1942 the US Geological Survey formed a Military Geology Unit (MGU) at Washington, DC of in-house and other earth scientists and engineers to gather terrain and related strategic intelligence. MGU compiled reports containing data about regions outside the USA as tables, text and maps for use by Allied forces, especially American and British. Benefiting to some extent from both Allied and German geological experience in World War I, MGU developed into by far the largest geology-based intelligence unit used to help guide Allied planning and operations in World War II. About 50 ‘Strategic Engineering Studies’ were completed in 1942, and at least 50 more in 1943. MGU products contributed significantly to the Allied campaigns in Sicily and Italy from 1943, and complemented British geotechnical work associated with Normandy and the NW Europe Campaign in 1944–1945. In 1944–1945, MGU deployed teams from Washington to US Army theatre headquarters in Europe, and more substantially to the SW Pacific and Pacific Ocean areas, principally to provide intelligence for strategic and tactical planning, and advice to and (in the Pacific) participation in combat operations. After 1945, MGU developed into a Military Geology Branch, responding to demands of wars cold and hot until 1972.