Enigma. The Battle for the Code: Hugh Sebag-Montefiore

Breaking the German Enigma codes was not only about brilliant mathematicians and professors at Bletchley Park. There is another aspect of the story which it is only now possible to tell. It takes in the exploits of spies, naval officers and ordinary British seamen who risked, and in some cases lost, their lives snatching the vital Enigma codebooks from under the noses of officials and from sinking German ships and submarines.

This book tells the whole Enigma story: its original invention and use by German forces and how it was the Poles who first cracked - and passed on to the British - the key to the German airforce Enigma. The more complicated German Navy Enigma appeared to them to be unbreakable.