This volume discusses how the German armed forces made effective use of military geologists to assist their fortification of the Channel Islands after their capture from the British in 1940. The book presents a unique case history of German geologist expertise applied to British terrain, intended to make the Islands into an impregnable fortress that postwar would remain a permanent outpost of the German state. In doing so, the book explains why the Channel Islands constitute a ‘classic’ location for British geology; how German armed forces made far greater military use of geologists than either their British or American opponents; and the legacy of fortifications that may conveniently be seen by tourists today – fortifications bypassed by Allied forces that liberated nearby Normandy after D-Day in June 1944, and surrendered intact at the end of the War in Europe in May 1945.