The A to Z Challenge asks bloggers to post 26 posts, one for each letter of the English alphabet, in April. Most of us choose to make these posts on a particular theme. My theme for 2022 is Codebreaking in World War II, which fits with the topic of the novel that I’m writing. Visit every day (except Sunday) in April for a new post on my topic.
E is for Enigma
Enigma is probably the first word that springs to mind when thinking about codebreaking in World War II.
Enigma was the name of a machine that enciphered messages. The messages were thought to be unbreakable, except by using another Enigma machine with the same settings. The Germans changed the setting each day in a process that was carefully guarded.
Enigma was originally marketed for commercial use in Germany in the early 1920s. A more complex version was used by Nazi Germany for military and government use before and during World War II.
Unbeknownst to the Germans, the Poles made progress at breaking Enigma messages in the early 1930s. One of the tools that Poland used was the bomba, a machine invented by Marian Rejewski. The bomba was designed to determine that day’s setting of the Enigma, by looking at the day’s Enigma messages.
Fortunately, Rejewski and the plans for the bomba managed to stay one step ahead of the Blitzkrieg so that the information could be shared with French and British cryptanalysts.
Alan Turing at Bletchley Park was inspired by the Polish bomba to design the British bombe. The design principle was different because, at about this time, the Germans made the Enigma more complicated.
The British Tabulating Machine Company made bombes for Bletchley Park and installations in outlying areas. These were run by Wrens – members of the Women’s Royal Naval Service.
When the US entered the war, and after several months of trust-building between the secretive cryptanalyst units, the National Cash Register (NCR) Corporation in Dayton, Ohio built bombes for the US Navy. The US also utilized women naval personnel – WAVES (Women Accepted for Volunteer Emergency Service). The women were stationed at Sugar Camp, originally a summer retreat for NCR salesmen.
For more information about Sugar Camp, check out Code Girls by Liza Mundy.
For all that Enigma is a well-known term associated with codebreaking in World War II, it is a complicated topic. I like the Enigma page on the Crypto Museum website, for further exploration, because it has lots of pictures to go with the text.
I’ll share this post on Friday in the British Isles Friday link party.