I was excited to review this book, and I was not disappointed; the book is “weird” in a really good way. The publishers classified the book as a computer science book, and, of course, they are not wrong. But it is also a history book and perhaps falls under a few other classifications as well. It is a well-deserved companion to the seminal text by David Kahn, The codebreakers [1], and will enjoy a place right next to it on my shelves.

This book is about cryptanalysis in general and the history of cryptanalysis in the Pacific theater during World War II. It is an important contribution to both the history of the war and the history of cryptanalysis development, as well as an interesting text on techniques of cryptography and cryptanalysis. (In that, I am not troubling the reader with the differentiation between cryptography and ciphering; this is a review and not a text.)

There is nothing shallow in this book. It is based primarily on archival documents, and the authors are commended for a heroic effort to track down and comprehend such a wealth of material. It is also simply well written and fun to read. The book is divided into six parts and 23 chapters. Each covers a quite different aspect. Part 1 discusses the general background and (modern) history of cryptanalysis. This part is mostly a history part; as an avid history student, I admit that for me this was the best part of the book! One of the really important points discussed here, as opposed to most other books on the subject, is the issue of data usage as part of cryptanalysis, such as traffic analysis, signals intelligence (SIGINT), and communications metadata. This was very well done and is timely and needed in the literature. This section is 90 pages: a small book in itself.

Part 2 is a technical view. It begins by discussing the various enciphering machines used by the Germans and Japanese during World War II and the period leading up to the war. Those interested primarily in the historical aspects concerning the war or concerning encryption need not dwell upon this part too thoroughly, although they might miss some good aspects of the book if they do. However, it is long and complex.

Part 3 discusses ciphers and submarines. It is short, but clobbers the reader. I strongly recommend the opening sections. Due almost entirely to superior intelligence, Germany lost more than six times the number of submarines as the US and UK combined! This is a phenomenal result.

Part 4 details the organization of the efforts, and Part 5 concludes the book. It is short (three pages) and is mostly devoted to remarks and kudos to those who played a significant role on the Allied side, such as William Friedman and Alan Turing. There is a sixth part, after the conclusion, that discusses additional historical background: a sort of “step-by-step” account of how the war in the Pacific progressed, from Pearl Harbor (the attack in December 1941) through the Philippines campaigns.

The book is well written and reads well. It is well referenced with myriad footnotes. I admire and recommend it. It is not trivial. The book has one glaring weakness, in that the story only includes the Allied side. It would have been valuable to see the Japanese intelligence and cryptanalysis efforts as well, at least for comparison. One can only surmise and guess what the result would have been had the Fugu Plan come to fruition, with Japan being the only country to have offered real solace and protection to European Jews, although this was blocked by the US government.