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The Hut Six Story: Breaking the Enigma Codes

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"Gordon Welchman worked at Bletchley Park, on the most important British de-ciphering operations of the war [WW2], from 1939 to 1945. Here, unsuspected by the Germans, the famous Enigma codes were broken, almost continuously throughout the war. Welchman was a leading figure at Bletchley Park; his brilliant mathematical mind, and imaginative attack on apparently insuperable problems, were of inestimable value in shaping the course of the war and hastening victory.

No other book has explained so thoroughly how the job was done, and how so often a flash of genius, an inspired insight, or even a stroke of luck, tipped the balance from failure to success, against all the odds.

Gordon Welchman, a talented mathematician, was educated at Marlborough, and Trinity College, Cambridge. He had taken up a post as a fellow of Sidney Sussex College when the war started, and he was an obvious recruit for the expanding codebreaking operations at Bletchley Park. He was awarded the OBE for his war work. After the war he emigrated to the USA, and continued to work on computers and their applications to security and communications. He died in 1985."


A publishing history is given on page 252, in Appendix III: First published by McGraw-Hill Book Co. Inc. in 1982, with a British edition appearing in the same year under the Allen Lane imprint. A paperback edition was published by Penguin Books in 1984.

326 pages, Paperback

First published January 1, 1982

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Gordon Welchman

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Displaying 1 - 30 of 33 reviews
Profile Image for Tiffany.
1,020 reviews99 followers
July 1, 2015
This book basically has two functions: 1) to describe Bletchley Park's service during World War II, and 2) to put forth military and communications lessons learned during WW II to be used in the future.

I enjoyed the Bletchley Park part of the book, although Welchman's descriptions of machines (Engima and the decoding bombes) and their operations sometimes were too technical for me. I also liked The Debs of Bletchley Park and Other Stories more as a behind-the-scenes of the operations and people at Bletchley, but this book provided another perspective.

The second function of the book (which takes up roughly the last 1/3 of the book), however, didn't do it for me as much. I don't have a big desire to know about military tactics, although the way he relates lessons learned during WWII was sometimes interesting; plus, the book is over 30 years old, so I don't know how much of it is still true. And that's the other thing: I'm not in a position to actually take any of the advice he gives (in case you don't know me, I'm not a military general or a person in high position in the US military or government), so I don't know if his recommendations have been put into practice, and I wouldn't know how to forward them anyway (not being a high-ranking member of the military or government). So for me, the last 1/3 was superfluous.
Profile Image for Bookish.
613 reviews145 followers
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April 14, 2017
I am currently reading The Hut Six Story: Breaking the Enigma Codes by Gordon Welchman. This nonfiction book is written by an insider at Bletchley Park in Britain as they pioneered breakthrough methods for breaking encrypted German wartime communications. I’m just getting started on this but I am already surprised at learning several new things—the availability of Enigma machines, the role of allied operatives in Poland, and the foundation of code-breaking tactics. There is another great tie-in for this book: The author and protagonist Gordon Welchman lived for decades in Newburyport, MA, just steps away the Firebrand Technologies/Bookish headquarters. The story is enlivened by archived TV interviews of local residents in Newburyport describing surprise interrogations of Gordon by “men in black” visiting his home as the layers of secrecy surrounding Bletchley Park were slowly peeled back after decades of silence. —Doug (https://www.bookish.com/articles/book...)
62 reviews
July 5, 2019
Really cool - very detailed account of the code breaking process of part of the secret Bletchley Park centre in Britain in WW2. Having just visited Bletchley myself it was great to get more detail. Understanding how the German Enigma machine worked is the easy part, it's very impressive how the Poles and Brits broke the codes so effectively. I liked a bit at the end where Gordon reflects on all the lucky breaks they had - sloppy procedures on the part of German operators, data shared by the Poles just before Hitler invaded them, luck of timing of various things that allowed them to continue just when they thought they were stumped, and weaknesses in the Enigma system the Germans never realised were a problem. Probably best read with a bit of context of Bletchley and the Enigma problem from other material too.
Profile Image for Thomas.
56 reviews
May 12, 2018
Gordon Welchman was one of the key persons at Bletchley Park who was not featuring in the great The Imitation Game movie, which focused almost entirely on the contributions of Alan Turing to the breaking of the Enigma codes during WW2. While I understand that the movie was a much belated praise and acknowledgement of Turing, the Bletchley Park story cannot be told without also acknowledging the contributions of Gordon Welchman.

In this book written in 1982, Welchman recapitulates the operations and impressive results achieved around 40 years earlier where the best minds of Britain - standing on the shoulders of Polish intelligence - managed to break Enigma codes even before the war really started. The book tells the story in a much more factual and less dramatic way than the movie, but what really stands back in my mind having read the book is how lost the British COULD have been with more than 200 trillion combinations of encodings that the Enigma offered had it not been for the almost oracle-like see-through of an array of basic human errors and complacencies in the use of the Enigma by the Germans. The Enigma was truly a work of art offering this deep level of encryption in a typewriter-style apparatus and based solely on wires, connectors and current, but the Germans seemingly forgot that in the end it was people operating and orchestrating the use of Enigma and the British saw the humans behind the flow of jumble and this led the way to breaking the codes - on a daily basis; all work started over from midnight! In that sense, the book serves to illustrate the cultural differences between a Kant’ish belief in an absolute truth; an optimum; and a more organic approach to life, which may not be as efficient in all aspects, but surely proved very effective in this case; fortunately for all of us!!

In the book, Welchman clearly but never explicitly competes with Turing for the claim to fame at Bletchley Park. Welchman eagerly acknowledges the contributions of the many people involved in the operations, which grew to some 250 people at the end of the war, but the book is almost completely void of praise for Turing! This to me indicates a too strong bias that somewhat dilutes the credibility of the story. Welchman has a lot to be proud of and he tells about his ground-breaking approach to analyse and deduct on the German signalling traffic, which has a direct line forward to modern day traffic analysis on the internet, as mastered by NSA for whom Welchman worked after the war. Moreover, his diagonal board improvements to the Bombe were vastly reducing the solution space and Welchman does not hesitate telling how he managed to convince Turing about these improvements. Yet you are left with the impression of a man who tries a little too hard and a little too late to make a name for himself.
Profile Image for ^.
907 reviews65 followers
February 4, 2015

Utterly fascinating; though at times I needed to keep pen & paper next to me in order to slowly work through some of the very mathematical sections (I have to confess to skipping others); this was well worth the effort.

What I really love about this book is that, for a talented mathematician, the author writes in good clear English; and he doesn’t restrict himself solely to the technicalities. I enjoyed learning how operations were ordered on and off site, and how the community both worked, socialised, and yet maintained the absolute tightest of secrecy. Truly awesome. One doesn't need a mathematical/scientific brain to read and enjoy this book; but if you do, you'll get more out of it.

Both times I have read this book after a visit to the Bletchley Park site (now a museum, next to The National Museum Of Computing), near Milton Keynes, Buckinghamshire, England. Highly recommended.
234 reviews2 followers
July 25, 2021
First hand account of working on breaking enigma codes.
Less polished than later accounts, like the very good Code book by Singh but more interesting for that. It gives you a real taste of how they actually went about breaking the enigma and the thought processes actually involved.

There is a large amount here about the importance of proper organisation and logistics which is left out of more mathematical books on enigma. There is only a small bit on network analysis which I thought this book went into in detail. Welchman is very complimentary of those doing network analysis but admits it his fame in the area is not from his actual work.

One odd thing is the fourth Section on Welchman's views on what would occur in the 1980's and 1990s is missing. Which is disappointing. Even if he was wrong it would be interesting to read this to see where such a clever person made mistakes in his predictions.
Profile Image for Lil.
249 reviews1 follower
October 1, 2012
I'm glad I read a first-hand account of life at Bletchley Park before diving into the other books about this place. Mr Welchman's account gives a very top-level view of the management there, which was interesting enough to make me want more details about the place. And I appreciated very much his inclusion of so many different skills into his calculations of what made their projects work - it wasn't just the mathematicians and engineers. But I got terribly lost in his detailed explanations of the workings of the Enigma machines and awfully critical about his views of current (well, 1982) warplanning. I am looking for more about the culture of Bletchley Park, and this book was not that. Still, a very engaging read.
Profile Image for Laura.
169 reviews
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August 4, 2020
I was thoroughly enjoying this book, if slightly baffled by science at some points, however it is clear from terms used that the intended audience were to be American - not a bad thing really, but a little frustrating
as it felt as us Brits weren’t as valid an audience even though speaking of British achievement.
The technical discussion at times could have benefitted from further diagrams to show workings/processes for those not so familiar with the workings of Enigma
282 reviews1 follower
April 15, 2024
I became interested in this book after watching a program about the author being classified by the US government as a security risk after writing a book 40 years after WWII about principally his involvement ( and other's contributions ) in breaking the German Enigma codes. The book starts out by break down the efforts prior to the war by the British with help of French and Polish individuals and teams ( prior to their respective invasions ) to understand and eventually crack the much vaulted unbreakable codes. Much of the success initially depended on human nature of the soldiers coding messages, taking shortcuts and predictable formatting. The author explains in detail the working of the Enigma Machines, its use by different segments of the German military and improvements made during the war by the British to automate decoding the daily settings for the apparatus. The latter being more commonly presented in documentaries about Bletchley Park. During the cold war that followed the author became involved in helping the United States develop sophisticated codes for its on use. And hence crossing the line in the back third of the book, not with publication of specific ideas, but wanting to publicly point out lessons learned from Enigma about human tendencies, including command silos, being the Achilles Heal of any coding process. Including the present. And perhaps at the time, crossing the line. He also spends some time citing communications and training as being the key reason for the Three Mile Island mishap. Not the technical processes involved. A warning regarding any type of code technology that would be developed.
This book is not quick read and you have to make the connections between many names during the Bletchley Park portion but as I stated at the beginning, it was the question of what is in this book sparked an investigation into the authors life, and per the program ruined his life, by the US government that lead me to getting an interlibrary loan ( its not widely available ) to find out. From what I can tell, he was just stating the obvious. Nothing secret there.



Profile Image for Daniel Bratell.
884 reviews12 followers
June 25, 2025
This is a unique retelling from a man that was central in Bletchley Park, the British decrypting centre, during the war. Gordon Welchman ran Hut 6, one of the departments at Bletchley Park, the one primarily responsible for decoding German army/air radio networks across Europe.

As I have read more of these books I have started to notice some contradictions, though they are mostly minor and mostly understandable considering the books were written 30-40 years after the war, when the classifications were eased.

Half of the book is about the war and is very interesting. The other half is about what the author calls "Today" which would be the early 1980s. I mostly ignored that part since it was not a historical document but a ideas and priorities for the future.

Welchman does seem bitter against Britain, something he has in common with R. V. Jones. They both seem to think that Britain made some extremely bad decisions post-war that floundered a scientific advantage. There is probably something to that, knowing how the British government rather destroyed the Colossus computers than made them public, handing the American ENIAC the title of "first computer" without competition.

Welchman is also very positive towards the USA, such as only an immigrant can be. He moved there right after the war and started working for the Americans and fell in love in the country.

It is not a long book, though it is a bit technical and might not be all that approachable. And if you ignore the second half, as I mostly did, it’s even shorter.

4 stars, but only on the first half. Second half I will pretend was not included.
Profile Image for RLD.
47 reviews1 follower
October 21, 2019
I chose to read this book based upon a discussion and recommendation on Facebook. I confirmed it by the good ratings given by Goodreads readers.

But I must say it was a complete waste of my time, and I read it all.
The author is a mathematician who should have used a ghostwriter. A real jumbled mess.
The stuff on the enigma codes are much better described in Wikipedia. And the author just can't stop talking about how good a job HE did.

A couple of things I did learn though. It was the laziness of the users of the system that helped the code breaker's work. But the other human error on the British end is that the code breaking was so secret that the many of the people they were communicating with didn't even know where the information was coming from and was trustworthy. They had uncovered the entire German plan to take Crete and were ignored.

There was a short bit of information stating that JFK was using a successful plan in Vietnam to stop the spread of the Viet Cong into the south. But the plan was abandoned after he died.
1 review
June 13, 2017
I was doing my rounds on you tube and came across the Bletchley Park story. This book was mentioned in the story and because of my interest in history, I bought the book.

The book narrates the secrets of how Welchman and other code breakers at Bletchley Park managed to decipher German coded messages transmitted through the enigma machine before and during the 2nd World War.

I enjoyed the narration of how the code breakers were able to capture and break the German codes but was somewhat lost with the mathematical aspect of code breaking, how the bombe machine worked and the whole process of enciphering and deciphering coded messages.

Overall i think this is one piece of history that had it not been told, we would not have known heroes like Welchman, Allan Turing and the rest of the code breakers who helped end 2nd World War earlier than expected.

Good read.
Profile Image for Marinho Lopes.
Author 2 books9 followers
April 16, 2019
Neste livro, Gordon Welchman descreve o papel de Bletchley Park na descodificação “industrial” de mensagens codificadas pela máquina Enigma pelos alemães durante a Segunda Guerra Mundial. Dado o secretismo envolvido, Welchman conta “apenas” aquilo de que estava a par, em particular, conta a forma como surgiu a Hut 6, os desafios que tiveram, e as soluções encontradas. Achei o livro muito interessante, embora algumas das explicações técnicas não me pareçam particularmente esclarecedoras. Em vez de exemplificar, teria sido mais claro se Welchman tivesse explicado a lógica abstracta de cada ideia em maior detalhe. Percebe-se que as ideias são todas muito simples, ainda que intrincadas… Desconfio, porém, que haja livros mais completos e esclarecedoras. Parte do interesse deste é ter sido escrito na primeira pessoa, por um dos “génios” responsáveis pelo sucesso de Bletchley Park.
106 reviews1 follower
January 24, 2024
This fine book will have you re-reading sections, just to understand some of the breakthroughs the author made. Although he was a mathematician, the way to break enigma involved strict logic. There is much of value here, especially in the explanation of his thought processes early on in his work. His insights were significant and they started with the belief that he had to get to know in precise detail how the machine worked, and also how the operators worked. It's fascinating to know that the Poles, Welchman and a separate team all came up with a similar approach to breaking Enigma. The Germans' biggest mistake was never to put a team to work as decoders. Had they realised that there were ways into recovering the messages, they would have changed operating procedures to make it impregnable.
16 reviews1 follower
January 8, 2019
The Hut Six story is an Autobiographical look at the Author's Time at Bletchley Park, in particular his experiences in the titular Hut 6 and his latter experiences as Director of Mechanization

I found myself engrossed reading about the function of the enigma machine, the development of the bombe, and the various methods used in cracking the codes. I also enjoyed reading about the polish contributions to the development of the methods, and how a lot of the code breaking was only possible due to mistakes made by the Germans.
4 reviews
January 28, 2022
the enigma code was a set of machines for sending messages between the Germans. over all I give this book 5 stars because of how it goes in to great depth of how the machine worked and what different codes meant. it also goes into the history of the enigma and how it was made. I think people who like history and want to learn a lot more about the enigma should read this but if your not that keen on history don't get this book because it will just be so boring.
35 reviews1 follower
March 12, 2017
A great study which combines interesting WWII history with the mechanisms by which crypto-systems fail in the real world.

Mandatory reading for anyone interested in crypto-systems and communications-security.
Profile Image for Bill Ardis.
46 reviews1 follower
February 4, 2018
Good history of Bletchely Park from someone who was there. Could get a little over technical at times (wished all of that material was in the appendix with better illustrations).
50 reviews
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February 16, 2021
Tough read. Lots of detail. So now I am fully qualified to crack Enigma codes, should it be needed.
Amazing story and amazing people.
Profile Image for Chris.
17 reviews
September 29, 2022
The book covers very interesting topics in general. However it often delves into minutiae which makes the book dry and harder to read.
Profile Image for Jim Perry.
58 reviews
June 29, 2023
Another Bletchley Park memoir, but interesting for its description of the human side (non-computer) of breaking a heavily encrypted message.
238 reviews
July 8, 2025
A very good personal account about breaking the enigma codes. Some chapters are very technical and difficult to follow but overall it is a great read
Profile Image for Sven.
53 reviews
October 28, 2025
Interesting in large parts, but still too technical and too detailed in parts. The last few chapters are actually quite boring to read and not so much about the codebreaking of the Enigma.
Profile Image for Glenn.
82 reviews9 followers
March 2, 2017
A fascinating book. Met all my expectations with a few extras. As others have remarked, the first half focuses on Bletchley park and the processes (predominately related to or within Hut 6 - where the focus was decryption and and Hut 3 where decrypts were turned into actual intelligence). Fills in significant detail on the organization, cryptanalysis and collection of manual processes without which the bombes would have been useless. The first half begins with a somewhat tedious but entirely necessary analysis of the operation of the Enigma and the basic manual decryption processes that allow the reader to better understand the rest of the book.

The 2nd half covers the author's experience when he worked with Mitre up until his retirement, and focuses the emerging battlefield network communications -- especially those related to aircraft. GW describes a better way for forward battlefield elements to communicate with one another without having to (WWII - style) switch back and forth between frequencies or wait till information had traveled up the tree to Command and back down again to forward elements that could best interpret the information and adjust their positions, tactics and strategy accordingly. He discusses a shared packet network where everyone is connected, messages are encoded to be short and specific, and elements can tune into only those they need to listen to -- (without having to worry about having to be on the right frequency at the right time.) There is also some history on early networking protocols buried in here - for those interested in those things.

The only reason I gave this book a 4 is because the last chapter (Secrecy, Security and Survival) is a bit pedantic and largely repeats views that were better covered in other parts of the book.

All & all, though, a very important historical work, by a Bletchley boffin, covering areas that tend to be ignored by the more recent "cult of Turing" authors.
Profile Image for Peter.
1,154 reviews46 followers
October 23, 2019
A fairly technical book about how the enigma codes were broken. More credit is given to the Polish codebreakers who were so crucial in getting the British operation up to speed than is shown in popular drama. The design of the bombes do not feature so much as how sudden inspirations occurred at random that allowed for cribs and shortcuts. There is a lot of technical stuff in the appendix that I did not have the patience to go through, but the technical information in the main body is plenty challenging (for me, at least).
Profile Image for Ray Noyes.
Author 17 books6 followers
April 21, 2016
I found the book fascinating, but one needs a very logical, mathematical brain to be able to understand some of the techniques described. My engineering background failed me much of the time.

It goes into surprising detail as to how the Enigma machine was understood but he stresses something very important: Bletchley Park's success was as much due to the errors committed by German Enigma operators as anything else. These errors provided 'cribs' from which key vides could be deduced.

Welchman also stresses how important was their monitoring and plotting of German wireless networks to track troop movements. One aspect that surprised me was the huge number of staff working on breaking codes. I had the impression it was of the order of several dozen very clever mathematicians, chess players and crossword solvers, but that would exclude the hundreds of staff operating the so-called 'bombes', those intercepting transmissions, those employed in decoding and admin work.
Profile Image for David Tussey.
21 reviews2 followers
December 31, 2015
A bit geeky, for sure, but an interesting story about one of the unsung heroes of WWII and the breaking of the German Enigma encryption device. Although Alan Turing often steals the spotlight on the Bletchley Park code-breaking team, it was actually Gordon Welchman (and his team) that did the cryptology necessary to actually find ways to break the code. Fun stuff...amazingly clever how they took a machine capable of 200 trillion combinations, and got it down to under 1000 in minutes of daily analysis.

This book was published some 40+ years after WWII, and yet it resulted in the author being disowned and having his security clearance pulled. Madness...especially when you see material inside this book.
Profile Image for Patrick Neylan.
Author 21 books27 followers
July 29, 2018
For the historian, Welchman's account is invaluable. But for the general reader it is too technical, concentrating on the mechanics of code-breaking in terms that are hard to understand.

Nor is Welchman much interested in the results of his work. No military achievements are mentioned and no dechiphered messages are quoted. Code-breaking is an end in itself.

It seems churlish to criticise him for not writing a book he never intended to write, but a reader interested in the wider story is likely to be disappointed.
Displaying 1 - 30 of 33 reviews

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