After a long period of silence, many books about the accomplishments of Allied forces in breaking the codes and ciphers of German, Italian and Japanese forces in World War II have been published over the last twenty years. Most of these books have been either written by one of the individuals who worked on a few of the specific enemy codes, or an editor who crafted a story by interviewing a number of people who were part of the Allied code breaking effort. Unlike most of other books on the subject, Code Breakers: The Inside Story of Bletchley Park is a collection of 30 first hand accounts about the daily grind and life at Bletchley Park and its outstations written by different individuals who worked there during WWII.

First, a little background about the subject of the book for those who may not be familiar the British code breaking activities in WWII. Government Code and Cypher School (GC&CS), the British organization responsible for intercepting and decoding foreign communications, was moved from London to Bletchley Park shortly before the start of WWII to provide a safer location. Bletchley Park (BP) started as a small operation with less than 100 people in 1939. By the end of the war, BP had broken almost all enemy ciphers and codes, including the formidable German mechanical encryption machines Enigma and Fish, and intercepted and decoded thousands of critical enemy messages that changed the course of the war. During this process, the headcount Bletchley Park had grown to more than seven thousand including some of the leading mathematicians in the world like Alan Turing.

Code Brekaers: The Inside Story of Bletchley Park gives as a cross section of the different kinds of people who worked at BP between 1939 to 1945. We learn about how they were recruited, what they worked on, how they attacked the problems, how they felt and what the general atmosphere was like.

The book is broken into five parts:

PART ONE covers the production of Ultra - the code name used for the information collected as a result of breaking of the enemy codes and ciphers. This was typically the large stage in the BP pipeline where messages which were already decoded by other groups were cleaned up, translated, sorted, filtered, and distributed to relevant military officials. In this section, ten different individuals tell us about how they were recruited, trained over a very short period of time and got thrown into a complex human-powered information machine. It is pretty amazing to see how much details these people can remember since they were not allowed to take any notes or talk to anybody about their work (including their wives/husbands) for almost forty years after the end of WWII.

PART TWO covers the most famous German code machine, the Enigma. This section contains detailed descriptions (again mostly from memory) of various variants of German Enigma machines and the tactics BP team used to decode messages, including many mistakes Germans made in designing and using these machines and the Bombes mechanical computers that were based on an original Polish design that were used to break codes through a combination of brute force and brain power.

PART THREE is about the Fish, the lesser known but (at least as far as the Germans believed) more secure encryption system that was used code the most critical communications between the German headquarters and commanders in the field. This cipher system can be considered to be the father of many of the systems that are in use, however, it was also eventually broken by the BP team. The complexity of this task was so daunting, however, that it lead to the invention and the construction of the first electronic computer in the world, the Colossus Mark I. The detailed descriptions of how the German fish machine was constructed in this section is excellent and the few weaknesses and operator errors BP team was able to exploit to break the code is truly amazing.

PART FOUR cover field ciphers and tactical codes. This is probably one of the most interesting sections of the book since codes used in the field had to be simple enough to be coded and decoded by nothing more than a pencil and paper. Therefore, even a reader without much background in math or engineering can not only understand how the codes worked but also the mechanisms the BP personnel used to break them.

PART FIVE covers the work done by BP on Japanese works. A lot of the work on Japanese codes were done by the USA cryptanalysts and British groups in Kilindini, Colombo and Australia. The Emperor's Codes: The Breaking of Japan's Secret Ciphers by Michael Smith gives a much more detailed account of the British intelligence work on Japanese codes.

I found this book very interesting because of the different perspectives it provides. It is fascinating to hear the stories from the people who did the real work. This may not the best first book to read on the Allied code breaking efforts during the second world war because the information is distributed in bits and pieces across the accounts of so many people. However, if you already have an interest in this area and if you have already read a book or two about Code Breakers during WWII, you should definitely follow up with this book.

Recommended: Yes