By the time of the Normandy invasion in June 1944, the U-boats were a beaten force, hunted and harried wherever they appeared by Allied warships and aircraft. The U-boats proved to be little more than pin pricks against the landings, and advancing Anglo-American armies had driven them out of their French west Atlantic bases all the way back to Norway by September 1944. Yet the U-boat force mounted a sustained and effective campaign from their Norwegian bases. Admiral Doenitz revived the U-boat War against Allied merchant shipping with new inventions in the face of a massive Allied naval defence while Germany collapsed. The east coast waters were shallow and heavily mined. Other German naval forces made a significant contribution. The campaign also saw the first and only appearances of the new Type XXIII electric U-boats, a radically new submarine design, the forerunner of modern diesel-electric submarines. John White examines in detail the U-boat reaction to the Normandy Landings in June 1944, the Norwegian U-boat bases, German torpedoes, the interference by U-boat Command, the Scapa Flow carrier operation and the Allied response up to the final surrender in May 1945.