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The story of the British and American codebreakers of the Second World War is now very well known, but the work of their German opponents is far less familiar. It gets mentioned from time to time – the most famous example probably being the breaking of the German diplomatic codes that allowed the Germans to read the incredibly detailed messages being sent home by the American attaché in Cairo, which meant that Rommel knew exactly where the British forces were, and what they were planning, and the breaking of various Allied naval codes is also mentioned, but it rarely goes beyond that. This book is an impressive attempt to redress the balance, looking at the structure of German codebreaking, the key individuals, what they actually did and what impact their work had on individual campaigns.
The first thing that stands out is that the Germans put a lot of effort into their codebreaking, but that it was rather badly scattered, with ten different agencies involved, some of them bitter rivals of each other. However despite not perhaps making the best use of their resources, the Germans managed to break into an impressively wide range of codes, from a wide range of countries. One of the nice features of this book is that we get understandable explanations of how the different Allied and neutral codes worked, the weaknesses either in the code itself or how it was used, and how the Germans broke into it.
This book should go a long way to balancing the rather smug attitude found in many books on British and Allied codebreaking. The achievements of the codebreakers at Bletchley Park were indeed very impressive, and it seems unlikely that the Germans could have achieved the same if faced by an Allied version of the Enigma machines. However for much of the German codebreakers were reading many Allied codes without having to make the same sort of effort, because many of the Allied codes weren’t as secure, and also because of repeated mistakes – such as when the Royal Navy changed from its first war cipher to its second the use of the two overlapped, so the Germans were able to break into the new code because some of the same messages were also being sent in the old code, or Bomber Command encrypting the single word message cancelling a bomb raid, giving the Germans a regular clue to that day’s RAF cipher.
One key advantage for the Allies was that they were willing to acknowledge that their codes might have been broken, while the Germans didn’t. During the war the Germans carried out several investigations of the security of Enigma messages, and each time concluded that they couldn’t be broken. In part this was because they didn’t consider the possibility of the brute force mechanical systems that were developed at Bletchley, but a key element was the impressive level of security about the Ultra intercepts. The British realised some of their codes had been broken when they in turn decrypted German messages that contained the original encoded British material. In contrast the Allies took much better care of the material decoded from the Enigma and other machines, so when the Germans examined the many messages they had decoded, they found no evidence that their own messages were being read. As a result most improvements in German encryption involved incremental improvements to the Enigma machine, which caused blackouts for the Allies, but were eventually defeated, whereas the Royal Navy introduced an entirely new cipher code in 1943, which the Germans struggled to deal with. The almost inevitable internal feuds within the Nazi regime also helped, as did the tendency later in the war for any unwelcome news from the code breakers to be ignored!
This is an excellent study of German codebreaking, explaining how it was organised, how it worked, what it achieved, how the results of its efforts contributed to the early German victories (with an especially good section on North Africa), and how the impact of the codebreaking efforts diminished as the war turned against Germany.
Part One: Germany Ascendant
1 – Losing the Signals Intelligence Battle in World War I
2 – The Enigma Salesman
3 – Germany’s New Codebreakers
4 – Preparing for War
5 – The Kriegsmarine Starts Listening
Part Two: Germany Offensive
6 – Two Navies at the Outbreak of War
7 – Romanian Codes and Romanian Oil
8 – Signals and Deception in the Invasion of Europe
9 – Fighting the War in the Air
10 – The Battle of the Atlantic
11 – Classical Enemies, Modern Codebreaking
Part Three: Germany at War
12 – Germany’s Mediterranean Battles
13 – Losing Enigma
14 – The Good Colonel
15 – Signals Intelligence and Cryptanalysis on the Russian Front
16 – The Enigmatic Swiss
17 – Rhubarb and Rodeo
18 – U-91 and the Battle of the Atlantic
Part Four: Germany Defensive
19 – The Battle of the Aegean
20 – Insecure Enigma
21 – The Coming Storm
22 – Execution and Capture
23 – The Collapse of the Third Reich
24 – The man with the Key has Gone
Author: Christian Jennings
Edition: Paperback
Pages: 368
Publisher: Osprey
Year: 2018