Joan Clarke, the cryptanalyst war-heroine, and the women of Bletchley Park (you never heard of)

Even if you’re not a History Buff, D Day is a term that rings the bell, right? June 6th, 1944, the Allied troops land on Normandy to fight the Nazis and begin the (cleverly named) Battle of Normandy. This resulted in the liberation of Western Europe from Germany’s control and the eventual Allied victory. Hoorray!

What you may not know, is that there was an extensive intelligence effort behind this battle, most of which happened on Bletchley Park. This was the central cite of the UK’s GC&CS (Government Code and Cypher School), tasked to penetrate secret communications of the Axis Powers. Some historians have estimated that the work done by the British Intelligence at Bletchley Park shortened the war by two to four years, and was a key element to the Allies’ success.

Bletchley Park Women working on computer

Young Joan Clarke in uniformNow: what if I told you that the Bletchley Park personnel was 75 % – 90% made up by WOMEN? And what if I told you that one of those women was part of the The Hut 8 team? Meet Joan Clarke, the woman who worked side by side with Alan Turing and Hugh Alexander on breaking the German cipher system Enigma (and succeeded).
Let’s break it down: the Germans had something called The Enigma Machine that encrypted their messages into code. Not knowing the settings meant the chances of being able to decipher a message was an astonishing 150 million million million to one. Talk about a high pressure job, right? But breaking the Enigma code was not a single-man (or single-group) task: it required constant contribution from a large personnel (over 10,000 people) including, in addition to cryptanalysts, clerks, machine operators, and intelligence and communications workers.

Joan had a double first degree in mathematics (she was denied a full degree by Cambridge because, until 1948, those were only awarded to men). Even though her promotion to Hut 8 was significant, because she was the first and only senior female cryptanalyst, bureaucracy had no protocols to give her a raise. Thus, she was classed as a linguist and from there on she filled the forms with “grade: linguist, languages: none” (and even then she was paid less than her male colleagues).

Naval Enigma (codenamed Dolphin) was more complex to break than the others, as there were more variables to the codes. The Hut 8 team worked on codes related to U-boats intelligence, that is, German ships hunting down (and sinking) Allied vessels carrying supplies and troops from the US to Europe. Britain at the time was importing half of its food and all of its oil from North America. After the German occupation of France, German ships had easy access to the Atlantic through the Bay of Biscay. The situation was dire: at one stage, Britain was only three days from running out of food.

Alan Turing had invented a new codebreaking technique called Banburismus that allowed to narrow down the possible code combinations from 336 to 20. Joan was not only the only female Banburist, but she was also one of the best. She devised a method of her own to speed up the technique. But to her surprise she was told she was using a technique called Dillysimus, devised in WWI (and it is thought that the reasons for not naming this improvement after Clarke were, certainly, sexist). Other women codebreakers included Mavis Lever, Ruth Briggs, Dilly Knox and Margaret Rock. But unfortunately little is known about their work as their contributions are hardly noted anywhere.

Joan Clarke Hut 8 team

Joan Clarke and the Hut 8 team, 1946 (I really wish this picture was larger)

Most importantly, all this code-breaking and cryptanalysis resulted in the first programmable computer, Colossuswhich was operated by women (click on that link for awesome then and now photos). Historical memory has not been fair to the civilians and service women of Bletchley Park. They are (and were at the time) commonly referred to as the ‘girls’ of Bletchley Park. The extreme secrecy around War Intelligence has prevented formal research until recently, so we might have to wait before we see significant work about these war heroines.


Never the less: you have Joan and the women of Bletchley Park to thank for changing the History of the World AND the fact that you’re reading this on a computer!

This is the second article on my series about Women in History. You can read the first one about Sor Juana Inés de la Cruz here. Tell me who you think I should write about next!


3 thoughts on “Joan Clarke, the cryptanalyst war-heroine, and the women of Bletchley Park (you never heard of)

  1. Pingback: Cipe Pineles, and the modern magazine layout. | Laura Vianello

  2. Pingback: Ada Lovelace, Math Witch and the World’s first Computer Programmer | Laura Vianello

  3. Pingback: 100 Years Ago: Joan Clarke – Jessica Montevago's Content Resources

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s