What do you think?
Rate this book
The Third Reich is Listening: Inside German codebreaking 1939–45
Drawing on recently declassified documents, and now available in paperback, this is the utterly compelling history of the successes and failures of the German Intelligence Services throughout World War II.
The success of the Allied codebreakers at Bletchley Park was one of the iconic intelligence achievements of World War II, immortalized in films such as The Imitation Game and Enigma . But cracking Enigma was only half of the story. Across the Channel, German intelligence agencies were hard at work breaking British and Allied codes.
Now updated in paperback, The Third Reich is Listening is a gripping blend of modern history and science, and describes the successes and failures of Germany's codebreaking and signals intelligence operations from 1935 to 1945. The first mainstream book that takes an in-depth look at German cryptanalysis in World War II, it tells how the Third Reich broke the ciphers of Allied and neutral countries, including Great Britain, France, Russia, and Switzerland.
This book offers a dramatic new perspective on one of the biggest stories of World War II, using declassified archive material and colorful personal accounts from the Germans at the heart of the story, including a former astronomer who worked out the British order of battle in 1940, a U-boat commander on the front line of the Battle of the Atlantic, and the German cryptanalyst who broke into and read crucial codes of the British Royal Navy.
The success of the Allied codebreakers at Bletchley Park was one of the iconic intelligence achievements of World War II, immortalized in films such as The Imitation Game and Enigma . But cracking Enigma was only half of the story. Across the Channel, German intelligence agencies were hard at work breaking British and Allied codes.
Now updated in paperback, The Third Reich is Listening is a gripping blend of modern history and science, and describes the successes and failures of Germany's codebreaking and signals intelligence operations from 1935 to 1945. The first mainstream book that takes an in-depth look at German cryptanalysis in World War II, it tells how the Third Reich broke the ciphers of Allied and neutral countries, including Great Britain, France, Russia, and Switzerland.
This book offers a dramatic new perspective on one of the biggest stories of World War II, using declassified archive material and colorful personal accounts from the Germans at the heart of the story, including a former astronomer who worked out the British order of battle in 1940, a U-boat commander on the front line of the Battle of the Atlantic, and the German cryptanalyst who broke into and read crucial codes of the British Royal Navy.
368 pages, Paperback
Published October 29, 2019
19 people are currently reading
143 people want to read
Ratings & Reviews
Friends & Following
Create a free account to discover what your friends think of this book!
Community Reviews
Displaying 1 - 13 of 13 reviews
July 19, 2021
A fascinating introduction to the Third Reich's military SIGINT efforts during WWII. Although the scope of the book covered all three branches of the German military, it emphasized Kriegsmarine and Luftwaffe activities. The Nazi Party organizations, e.g. RSHA and SS were only superficially addressed. A shortcoming of the narrative in my opinion.
The story was told from three angles - 1) operationally how SIGINT played a role in some of the major wartime operations, 2) activities at a personal level for tactical SIGINT, cryptanalysis and cryptography, and 3) technically providing short explanations as to how cryptography and cryptanalysis is applied. The blending of these three narratives, plus the author's desire to discuss WW2 operational details mixed in with the SIGINT accounts I found a distraction of telling the SIGINT story and a waste of page space.
The engaging aspects of the book were the details provided about the military SIGINT organizations and some of the key SIGINT personnel. the various German investigations into the possibility Enigma had been broken, the role SIGINT played in both the North Africa Campaign and the Atlantic Campaign. The end of war investigation by the US Army TICOM units to find and capture both German SIGINT personnel, document and equipment should be a book all of its own.
Missed 4 stars due to the issues described above, but overall a valuable contribution to the small but growing historical documentation of WW2 SIGINT, even if needlessly shortened by the insertion of WW2 operational details. A recommended read for both those interested in the history of SIGINT and those with an interest in WW2 to understand how SIGINT significantly shaped some of the campaigns and individual battles fought.
The story was told from three angles - 1) operationally how SIGINT played a role in some of the major wartime operations, 2) activities at a personal level for tactical SIGINT, cryptanalysis and cryptography, and 3) technically providing short explanations as to how cryptography and cryptanalysis is applied. The blending of these three narratives, plus the author's desire to discuss WW2 operational details mixed in with the SIGINT accounts I found a distraction of telling the SIGINT story and a waste of page space.
The engaging aspects of the book were the details provided about the military SIGINT organizations and some of the key SIGINT personnel. the various German investigations into the possibility Enigma had been broken, the role SIGINT played in both the North Africa Campaign and the Atlantic Campaign. The end of war investigation by the US Army TICOM units to find and capture both German SIGINT personnel, document and equipment should be a book all of its own.
Missed 4 stars due to the issues described above, but overall a valuable contribution to the small but growing historical documentation of WW2 SIGINT, even if needlessly shortened by the insertion of WW2 operational details. A recommended read for both those interested in the history of SIGINT and those with an interest in WW2 to understand how SIGINT significantly shaped some of the campaigns and individual battles fought.
June 28, 2021
I picked this book up from the bookshop at Bletchley Park (which has an extremely helpful and knowledgeable member of staff to proffer advice) – as I was interested to read the “other side” of the by now familiar Alan Turing/Enigma/Bletchley Park story.
“History is written by the winners” as Churchill (like so many other things) did not say – and this is definitely the case in the area of World War II Cryptography and this book seeks to address the imbalance by giving a German experience on codebreaking (both their attempts to break codes and their attempts to stop their own codes being broken) from 1939-45.
Actually in practice the book is even wider than that in at least three senses – both time and country and codebreaking.
Time: after a Preface set in 1945 as the Allies try to find the coding files that the defeated Germans have tried to destroy – the book begins with a chapter set in the First World War – where the Germans (particularly the German Navy) heavily lost the Signals Intelligence Battle. The key reason for that was the Germans use of huge codebooks (so big and widely distributed that their replacement was impossible and their theft inevitable). The next few chapters concentrate on the German preparations for war – heavily undercover due to the Versailles Treaty and heavily motivated by WWI lessons learned: this inevitably attracted the Germans to the Enigma machine.
Country: the book, although mainly concentrated on Germany and their attempts to break English codes (and vice versa) often breaks off to consider the efforts of other countries (Allied, Axis and various neutral powers at various points on the Allied-Axis spectrum) as well as German attempts to break these codes.
And this probably gets at one of the issues with this book – a lack of clear focus and of a real underlying story to match say Churchill’s visit to and support of Bletchley Park.
But this itself is perhaps a key lesson of the book: early on (and again in the conclusion) Jennings reaches the conclusion that two of the key failures of German cryptography were: its fragmentary nature (with around 10 different organizations who were not just un-coordinated or in inter-service rivalry but actively hostile to each other – not least due to differing degrees of Nazification); the inability of German leadership to act on the intelligence (not least due to the paranoia and fear of Hitler).
Codebreaking: although with a key cryptography focus the book ends up a little like a full WWII European/African military history as well – albeit this is because one of the author’s key contentions is that intelligence is useless without the military means to act on it.
Some areas that I found of particular interest
One of the main German assets (the equivalent I think of the Japanese attaché who spoke regularly with Hitler and later toured the French coast defenses – relaying everything back to Tokyo in a code the Allies had long ago broken) was an American military attache Colonel Fellers who using an (already compromised US Diplomatic code) transmitted huge amounts of detail on almost all aspects of the Allied war effort to the State Department (all of which the Germans intercepted).
Even pre-War the Germans had made huge progress in breaking the British navy codes particularly the Merchant Navy ones and made even greater progress once the war had started (which particularly gave them a sustained early advantage against convoys in the Battle of the Atlantic). Some reasons for this included the Germans having lost of cribs and depth from things like the British use of standard reports, the repeated transmission of the same message via different channels and cyphers, the ability to generate their own cribs due to having observer at ports (so knowing when ships would report their arrival), from knowing the position of their own ships (so being able to look for messages reporting those locations) and even from using the intelligence in Lloyd’s List.
The Germans seemed to be convinced Enigma was unbreakable: partly due to the Allied success in keeping its break so secret; partly as they made blind attempts to break it themselves and failed – at one point rather astonishingly it is said that the attempts to break it never focused on the fatal flaw that no letter was every transposed as itself); partly also though that – seeing as the English codes were non-mechanical compared to Enigma, they never conceived that the English codebreaking would not just be mechanical but would invent a whole new discipline of computing.
Overall a valuable complement in subject matter, research and original angle to the more conventional Enigma books but perhaps not the best executed in style and editing.
“History is written by the winners” as Churchill (like so many other things) did not say – and this is definitely the case in the area of World War II Cryptography and this book seeks to address the imbalance by giving a German experience on codebreaking (both their attempts to break codes and their attempts to stop their own codes being broken) from 1939-45.
Actually in practice the book is even wider than that in at least three senses – both time and country and codebreaking.
Time: after a Preface set in 1945 as the Allies try to find the coding files that the defeated Germans have tried to destroy – the book begins with a chapter set in the First World War – where the Germans (particularly the German Navy) heavily lost the Signals Intelligence Battle. The key reason for that was the Germans use of huge codebooks (so big and widely distributed that their replacement was impossible and their theft inevitable). The next few chapters concentrate on the German preparations for war – heavily undercover due to the Versailles Treaty and heavily motivated by WWI lessons learned: this inevitably attracted the Germans to the Enigma machine.
Country: the book, although mainly concentrated on Germany and their attempts to break English codes (and vice versa) often breaks off to consider the efforts of other countries (Allied, Axis and various neutral powers at various points on the Allied-Axis spectrum) as well as German attempts to break these codes.
And this probably gets at one of the issues with this book – a lack of clear focus and of a real underlying story to match say Churchill’s visit to and support of Bletchley Park.
But this itself is perhaps a key lesson of the book: early on (and again in the conclusion) Jennings reaches the conclusion that two of the key failures of German cryptography were: its fragmentary nature (with around 10 different organizations who were not just un-coordinated or in inter-service rivalry but actively hostile to each other – not least due to differing degrees of Nazification); the inability of German leadership to act on the intelligence (not least due to the paranoia and fear of Hitler).
Codebreaking: although with a key cryptography focus the book ends up a little like a full WWII European/African military history as well – albeit this is because one of the author’s key contentions is that intelligence is useless without the military means to act on it.
Some areas that I found of particular interest
One of the main German assets (the equivalent I think of the Japanese attaché who spoke regularly with Hitler and later toured the French coast defenses – relaying everything back to Tokyo in a code the Allies had long ago broken) was an American military attache Colonel Fellers who using an (already compromised US Diplomatic code) transmitted huge amounts of detail on almost all aspects of the Allied war effort to the State Department (all of which the Germans intercepted).
Even pre-War the Germans had made huge progress in breaking the British navy codes particularly the Merchant Navy ones and made even greater progress once the war had started (which particularly gave them a sustained early advantage against convoys in the Battle of the Atlantic). Some reasons for this included the Germans having lost of cribs and depth from things like the British use of standard reports, the repeated transmission of the same message via different channels and cyphers, the ability to generate their own cribs due to having observer at ports (so knowing when ships would report their arrival), from knowing the position of their own ships (so being able to look for messages reporting those locations) and even from using the intelligence in Lloyd’s List.
The Germans seemed to be convinced Enigma was unbreakable: partly due to the Allied success in keeping its break so secret; partly as they made blind attempts to break it themselves and failed – at one point rather astonishingly it is said that the attempts to break it never focused on the fatal flaw that no letter was every transposed as itself); partly also though that – seeing as the English codes were non-mechanical compared to Enigma, they never conceived that the English codebreaking would not just be mechanical but would invent a whole new discipline of computing.
Overall a valuable complement in subject matter, research and original angle to the more conventional Enigma books but perhaps not the best executed in style and editing.
June 22, 2019
A clear, engaging overview of German codebreaking. Jennings writes in the beginning that he only covers a small part of the story, and most of the book deals with how German codebreakers were able to support German forces in battle.
Jennings covers German successes in breaking the codes of the Royal Navy (the same ones, by 1939, that they had been using for years) and the British merchant marine, as well as how German codebreaking feats enabled them to collect on Allied air force units in England and often provide advance warning of bomber raids (and gain some insight into the timing of and probable locations of Overlord) He also reminds the reader that the Germans were aware that Poland had cracked the Enigma, shortly after their invasion of that country. Jennings also writes that the Germans were largely conscious of the American and British breaks into the Enigma code, but were unable to plug these breaches for a variety of reasons.
Jennings also describes how, while the Allies were able to use decrypted German signals to gain a clear picture of German strategy and industrial output, the Germans struggled with this. Also, the leaders of the Western democracies were able to consider intelligence even when it wasn’t what they wanted to hear; the Germans often seemed to completely ignore their spooks when it came to important decisions. Jennings also describes how German code-breaking organizations existed in giant bureaucracy where no one was really in charge of the whole enterprise; there were about eight different groups, and none of them cooperated well with each other.
There a couple errors here and there, some of them nitpicks, some of them pretty strange; at one point Jennings writes of the “Third Reich” (in 1927), of “heavy cruisers” at Jutland (what?), that the British received oil from Libya (during the war?), that the Germans used torpedoes with acoustic homing devices (in 1939?), that the British received iron ore from Norway (not Sweden?), that the Allies expected the Germans to invade across the Maginot Line (they did?), and a “Secretary of Foreign Affairs” named Klaus von Bülow (who? And doesn’t he mean “minister”?) Jennings calls the NKVD the “KGB” (during the war) Elsewhere, when discussing Soviet targets, he writes of the Comintern and the “Central Committee” as if they were the same organization. In another part of the book he writes that Atlantic convoys were both “easy to find” and the U-boats’ “primary challenge.”
A well-written, interesting and fast-paced work.
Jennings covers German successes in breaking the codes of the Royal Navy (the same ones, by 1939, that they had been using for years) and the British merchant marine, as well as how German codebreaking feats enabled them to collect on Allied air force units in England and often provide advance warning of bomber raids (and gain some insight into the timing of and probable locations of Overlord) He also reminds the reader that the Germans were aware that Poland had cracked the Enigma, shortly after their invasion of that country. Jennings also writes that the Germans were largely conscious of the American and British breaks into the Enigma code, but were unable to plug these breaches for a variety of reasons.
Jennings also describes how, while the Allies were able to use decrypted German signals to gain a clear picture of German strategy and industrial output, the Germans struggled with this. Also, the leaders of the Western democracies were able to consider intelligence even when it wasn’t what they wanted to hear; the Germans often seemed to completely ignore their spooks when it came to important decisions. Jennings also describes how German code-breaking organizations existed in giant bureaucracy where no one was really in charge of the whole enterprise; there were about eight different groups, and none of them cooperated well with each other.
There a couple errors here and there, some of them nitpicks, some of them pretty strange; at one point Jennings writes of the “Third Reich” (in 1927), of “heavy cruisers” at Jutland (what?), that the British received oil from Libya (during the war?), that the Germans used torpedoes with acoustic homing devices (in 1939?), that the British received iron ore from Norway (not Sweden?), that the Allies expected the Germans to invade across the Maginot Line (they did?), and a “Secretary of Foreign Affairs” named Klaus von Bülow (who? And doesn’t he mean “minister”?) Jennings calls the NKVD the “KGB” (during the war) Elsewhere, when discussing Soviet targets, he writes of the Comintern and the “Central Committee” as if they were the same organization. In another part of the book he writes that Atlantic convoys were both “easy to find” and the U-boats’ “primary challenge.”
A well-written, interesting and fast-paced work.
September 9, 2023
A fantastic look at the other side of the Enigma story. Using insights into the personal story of the German officers you really get a glimpse into the workings.
May 1, 2019
An important story is told well. The details regarding the more detailed aspects of encryption methods and strategies are pretty opaque to the average reader. The historical aspects are interestingly detailed
January 14, 2019
Fascinating- completes the story we’ve learned from Bletchley, with the other side of the coin
September 8, 2023
Why did the Germans not suspect the allies were breaking Enigma? This question is very thoroughly answered. They did several times and held security reviews. There was no mention of it in the British own coded traffic, nor any information that could only come from the decryption of German codes. The British own naval codes seemed to be inferior. Since they stayed with the old code books, the British must have thought they where secure.- Or so the Germans could have reasoned. This all seems very reasonable to me. (What I do not understand is the British side of it: Why did they keep using the insecure code books. They must have known from cracking Enigma that their own code where not secure?)
The difference in personal is striking: Bletchley Park had 10,000 people working at factory scale code cracking. The German staff was split over a large number of codebreaking agencies that did not cooperate. The largest number of employees mentioned is 250 people. And yet they were at times reading most of the traffic.
I also very much liked the Rommel chapter. Before I had the impression that Rommel did so well due to being a strategical genius. Due to code breaking ”Rommel, each day at lunch, knew exactly where the Allied troops were standing the evening before.” …. ah, that makes it so much easier to be a strategical genius.
Two things I did not like:
1) There are a lot of extra details of battles that are not about codebreaking. A wast of time.
2) I got the unfortunate impression that the author did not actually understand the cryptography:
”Polyalphabetic substitution is a technique whereby one set of letters is substituted for another. A plain text set of letters is substituted for another, as previously explained, in a monoalphabetic substitution. In a polyalphabetic one, this first enciphered alphabet is again substituted for another, so it is effectively encoded twice.”
No, polyalphabetic means using several alphabets, one for the first letter, another for the second letter. Encoded twice with a monoalphabetic do not add security, as it correspondences to a different single monoalphabetic encoding (it is not obvious, but a mathematical result).
”The sender of the message would add on a double repetition of the key to be used so that the receiver did not make any errors. So at the start of each message they would add on three letters – say, HTR – twice. These six letters – HTR – were then put into the daily cipher code on a setting of the Enigma’s rotors that was decided between the sender and recipient. As a result, the Poles now had two sets of letters which repeated themselves, giving them a daily crib into the setting of the Enigma machine.”
Normally a crib is a bit of plaintext that is known (or assumed) to appear in the plaintext. The double key is not a crib, since the content is not know, only that letter 1 and 4 and so on is the same.
The difference in personal is striking: Bletchley Park had 10,000 people working at factory scale code cracking. The German staff was split over a large number of codebreaking agencies that did not cooperate. The largest number of employees mentioned is 250 people. And yet they were at times reading most of the traffic.
I also very much liked the Rommel chapter. Before I had the impression that Rommel did so well due to being a strategical genius. Due to code breaking ”Rommel, each day at lunch, knew exactly where the Allied troops were standing the evening before.” …. ah, that makes it so much easier to be a strategical genius.
Two things I did not like:
1) There are a lot of extra details of battles that are not about codebreaking. A wast of time.
2) I got the unfortunate impression that the author did not actually understand the cryptography:
”Polyalphabetic substitution is a technique whereby one set of letters is substituted for another. A plain text set of letters is substituted for another, as previously explained, in a monoalphabetic substitution. In a polyalphabetic one, this first enciphered alphabet is again substituted for another, so it is effectively encoded twice.”
No, polyalphabetic means using several alphabets, one for the first letter, another for the second letter. Encoded twice with a monoalphabetic do not add security, as it correspondences to a different single monoalphabetic encoding (it is not obvious, but a mathematical result).
”The sender of the message would add on a double repetition of the key to be used so that the receiver did not make any errors. So at the start of each message they would add on three letters – say, HTR – twice. These six letters – HTR – were then put into the daily cipher code on a setting of the Enigma’s rotors that was decided between the sender and recipient. As a result, the Poles now had two sets of letters which repeated themselves, giving them a daily crib into the setting of the Enigma machine.”
Normally a crib is a bit of plaintext that is known (or assumed) to appear in the plaintext. The double key is not a crib, since the content is not know, only that letter 1 and 4 and so on is the same.
April 21, 2023
The Third Reich is Listening: Inside German Codebreaking 1939 – 45 by Christian Jennings is a significant contribution to our understanding of Second World War history. As Jennings notes, the work of Bletchley Park is deservedly well-known. In this volume, Jennings reveals how truly accomplished were the German cryptologists. In nearly every way, they were the equals of the sleuths at BP. In some ways, they were even more accomplished, for instance, in breaking the scrambler transmissions between Churchill and Roosevelt. By war’s end, the Germans were listening in on communications of more than thirty nations. Jennings also reveals how the British, particularly, were extraordinarily lax in their own enciphered communications, easing the path for the German sleuths. The primary failing amongst the Germans was their organizational handling of their results. With the exception of the naval intelligence which enabled the U-boat wolf packs to decimate Allied shipping early in the war, much of the intelligence obtained by the cryptologists was never put into action. It’s complicated. At the end of the war, the Allies captured an enormous amount of source material that is only recently becoming available to historians. Jennings has dipped into that vast trove which is providing far more technical details than what has survived from BP. As these materials get incorporated into future academic accounts of the Second World War, they will likely engender major changes to conventional accounts. The Third Reich is Listening is a must-read and I unhesitatingly give it one of my rare five-star ratings.
August 12, 2025
Very Interesting and Informative - but text vocal in parts
I learned that the German code breaking was just as smart as that of the allies, (helped by allied code security being poor). Brings interesting balance to the narrative. A bit technical in parts for me, but those bits quite small and easily skipped - a bit like the songs in Lord of the Rings ;)
I learned that the German code breaking was just as smart as that of the allies, (helped by allied code security being poor). Brings interesting balance to the narrative. A bit technical in parts for me, but those bits quite small and easily skipped - a bit like the songs in Lord of the Rings ;)
October 28, 2021
The book gives interesting insights in the structure, abilities and operations of the different German code breaking organisation. It focuses less on the mathematics behind code breaking than on the personalities involved and their role during the war.
March 3, 2024
So how do we score a book on Nazi codebreakers that has virtually nothing to say about Nazi war crimes but spends most of the chapter on the Eastern Front recounting lurid tales of Soviet atrocities seemingly drawn from The Black Book of Communism?
Is it one star? I think one star is correct.
Is it one star? I think one star is correct.
May 2, 2020
I came across the author's Google Authors@Google talk and was fascinated since this story is rarely told.
April 30, 2020
As an abbreviated Kindle sample, this was an intriguing adventure. It is well written and manifests a supreme level of fact correlation. How it begins with the successes of the English cryptographers in breaking into WW I German transmissions using captured metaphorical keys to the front door is an attention-grabbing lead-in. That the Germans retained their coding system into WWII is incomprehensible. If I find this again, I'll likely resume where I left off in the development of the Enigma machine leading into the build-up to WWII. So far, this is not about how Germans intercepted and decripted Allies' transmissions, but only about their own failures in this field.
This entire review has been hidden because of spoilers.
Displaying 1 - 13 of 13 reviews