DONITZ'S LAST GAMBLE

By the end of 1943 the German submarine war on Atlantic convoys was all but defeated, beaten by superior technology, code breaking and air power. With losses mounting Donitz withdrew the wolfpacks but, in a surprise change of strategy, following the D-Day landings in June 1944 he sent his U-boats into coastal waters, closer to home, where they could harass the crucial Allied supply lines to Europe.

Caught unawares, the Royal Navy and the US Navy struggled to cope. In shallow waters submarines could lie undetected and, given operational freedom, rarely need to make signals - neutralising the Allied advantages of decryption and radio direction finding. 

This offensive was, perhaps, Germany's last chance of turning the tide yet, surprisingly, this important element of the U-boat war has never been told in detail before. That it did not succeed masks its significance: the threat of quiet submarines operating singly in shallow water was never fully mastered and, in the Cold War that followed, the Soviet submarine fleet using captured German technology and tactical experience became a very real menace.