A bit slow at first but good in the way it brings all the stories together as 1 summary. ( )

I've read at least one book on this topic before. This one is quite detailed on the mechanics of the machine and how the codes work. ( )

Interesting book about how the British were able to figure out the German codes during the War. I skipped the detailed mathematical explanations of how they did it, though, which was mostly at the end, in the Appendixes.
I found out Alan Turing did a lot, but he worked with much decoding already done by a Polish team earlier, and had help from others too. The vanquished U-Boats and the rescuing of their codebooks, and other stories, such as the espionage in France were interesting too. This book gives a more complete story than the movie, The Imitation Game, which was very oversimplified. ( )

In depth, comprehensive and excellent. Can be a bit dry because of the factual nature, but well worth reading to understand the intricacies and difficulties of keeping and breaking the Enigma codes. Lots of explanations of the various codes and how they were broken - this author definitely understands the subject matter. ( )

The story of the breaking of the Enigma code in World War 2 is a fascinating one. It is filled with brilliance, daring, danger and betrayal. Hugh Sebag-Montefiore has written an exemplary history, combining extensive archival research with gripping prose. Churchill was as aware as anyone of the importance of the success, or failure, of codebreaking efforts at Bletchley Park. He described those who worked there as “The goose that laid the golden egg and never cackled”. Secrecy was of the essence. Sebag-Montefiore describes the challenges of utilising the intelligence gained from breaking German military coded messages, whilst ensuring that the German’s never found out, thus ending this advantage.
Several times doubt was cast on the security of Germany’s ciphers. The book focusses particularly on the doubts of Admiral Donitz, head of the German Navy who seems to have been the most security conscious high commander. Several times he requested investigations, and the updated edition of the book uses new evidence to cast particular attention on a 1943 investigation which once again reassured the Germans of the safety of the code, as usual on spurious grounds.
The core of the book however focuses on how Britain ended up being able to break the code. Sebag-Montefiore justly praises the work of the Bletchley Park codebreakers, acknowledging the well known Alan Turing but also examining the contributions of other codebreakers such as Dilly Knox, Gordon Welchman and Harry Hinsley. The book contains some excellent descriptions of the codebreaking process, including a number of appendices describing in more detail such idiosyncratic practices as bombes, cillis, rodding and banburismus.
One of his main themes though is how the all important (and most difficult) naval codes would probably never have been broken just through the brilliance of the mathematicians at Bletchley Park. Frank Birch, head of the German section recounted how in late 1940 Turing and Twinn approached him in dispair of breaking the naval code. “The burden of their song was the importance of a pinch. Did the authorities realise that since the Germans did the dirt on their machine on 1 June there was very little hope if any of their deciphering current, or even approximating current, enigma for months and months and months – if ever?”
Sebag-Montefiore describes the missions to carry out ‘a pinch’ of German coding equipment and materials dramatically, with vivid scenes of desperate attempts to recover books from trawlers and U-Boats. He also provides a gripping passage on the drama of convoy PQ17, a tragic victim of slow codebreaking and difficult decisions.
Another fascinating story is that of the pre-war efforts of the French and Poles, including a dangerous espionage game with Hans Thilo Schmidt, who worked in the German cryptography office. His is an exciting and tragic story of a character who can either be looked at as a hero for the allies, or a money-motivated traitor. Either way his contributions were important for the pre-war codebreaking efforts of all parties in various ways. His information was initially useful for the Poles, who went on to complete some extraordinary work breaking Enigma in the pre-war years.
The story of “Ultra” and the breaking of Enigma is exciting, multifaceted and an important aspect of the victory over the Germans. As Sebag-Montefiore points out it was not a central or perfect factor. Success at codebreaking came and went, was not always timely and was always contingent on there being sufficient military force to exploit the knowledge. It is an important story though, and this book certainly gives it justice.
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