British experts had already broken many of the Enigma codes for the Western front. Enigma was the Germans’ most sophisticated coding machine, necessary to secretly transmit information. The Enigma machine, invented in 1919 by Hugo Koch, a Dutchman, looked like a typewriter and was originally employed for business purposes.
The German army adapted the machine for wartime use and considered its encoding system unbreakable.
They were wrong. The Brits had broken their first Enigma code as early as the German invasion of Poland and had intercepted virtually every message sent through the occupation of Holland and France. Britain nicknamed the intercepted messages Ultra.
Now, with the German invasion of Russia, the Allies needed to be able to intercept coded messages transmitted on this second, Eastern, front. The first breakthrough occurred on July 9, regarding German ground-air operations, but various keys would continue to be broken by the Brits over the next year, each conveying information of higher secrecy and priority than the next. (For example, a series of decoded messages nicknamed “Weasel” proved extremely important in anticipating German anti-aircraft and antitank strategies against the Allies.) These decoded messages were regularly passed to the Soviet High Command regarding German troop movements and planned offensives, and back to London regarding the mass murder of Russian prisoners and Jewish concentration camp victims.
As a side note to this, there was a film in 2001 titled Enigma. It was fictional story based on the time period. What I found interesting about the information about the film is that is was co-produced by Mick Jagger of the Rolling Stones and the enigma machine used in the film is owned by him.
I never heard of the film before writing this post. My favorite code breaking story in film is the Battle of Midway, which of course is Japanese code in WWII.
Code breaking is a big part of the British television series, titled The Bletchley Circle. It is about the post war work of expert code breakers from Bletchley Park, Britain’s main decoding establishment during WWII. I wrote about this series previously in my post History from the Small Screen – The Bletchley Circle.