The story of Enigma and the breaking of the seemingly impregnable German codes during World War 2 is a fascinating one. After World War 1, the German admirals were shocked to discover that the Royal Navy had penetrated their secret radio codes. Confronted with this fact, the postwar German navy determined that such a penetration would never occur again. Future codes were going to be so complex that breaking them would, theroetically, be impossible. The result was the famous and at that time highly secret Enigma machine. With it, the German authorities believed radio transmissions were wholly secure even if a captured machine fell into the wrong hands. German confidence was misplaced, however. During World War 2 Polish cryptanalysts helped Britain break into the Enigma system used by the German army and the Luftwaffe, but the naval version was more complicated. During the Battle of the Atlantic, U-boats operating in Wolf Packs wrought terrible destruction on the convoys bringing vital war supplies to Britain. To break the naval code, Britain desperately needed some U-boat Enigma machines as well as the code books to operate them. This book analyses the development of Enigma, its role during German U-boat operations and the subsequent code-breaking work at Bletchley Park. The book examines in detail all the U-boats known to have been boarded by the Allies during the war drom which Enigma machines could have been captured.