How 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 – 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 will explain 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.