Quarterly Journal of Engineering Geology and Hydrogeology, 45, 349 –367 DOI: 10.1144/1470-9236/11-054. 1470-9236/12 $15.00 © 2012 Geological Society of London

US Geological Survey (USGS) entered World War II without a unit of military geologists. Germany had invaded Poland in September 1939, and the Soviet Union had faced German attack in June 1941, with no such handicap. Germany had re-founded a military geo-logical organization as such before the war (Häusler & Willig 2000), and from the beginning of the war Soviet forces ‘employed a large body of geological specialists ’ (Kiersch & Underwood 1998, p. 22), some of them as in Germany presumably veterans from World War I. However, during the interwar years, the US Army Corps of Engineers and the USGS, like the British Army, its Royal Engineers, and the Geological Survey of Great Britain, had failed to build significantly on their own legacy of militarily applied geology from the 1914–1918 war. This paper describes how a Military Geology Unit (MGU) was raised in the USA in 1942, as the first Allied unit to use primarily geologists to gather terrain and related strategic intelligence infor-mation, and how this developed into by far the largest such unit to support Allied military operations. Unlike a smaller British unit later raised in the UK, as recently described in the Quarterly Journal of Engineering Geology and Hydrogeology (Rose & Clatworthy 2008b), and the German military geological organization, although funded by the military the American unit was not raised within the armed forces but within the national geological survey, the USGS. MGU’s founding and operations have often been mentioned briefl