Ladies of Cryptography: The Women Who Broke War’s Codes

Book review: Code Girls, by Liza Mundy

I’m in some kind of hush, hush business. Somewhere in Wash. D.C. If I say anything I’ll get hung for sure. I guess I signed my life away. But I don’t mind it.

Code Girls, author Liza Mundy’s history of the women who worked tirelessly cracking codes to aid the American Army and Navy in World War II, opens with this quote from Jaenn Magdalene Coz, extracted from a letter to her mother, and never lets up from there.

Mundy notes in this group biography that it’s well-known how many women enthusiastically contributed to the war effort, particularly in factories, immortalized by Rosie the Riveter.

Far less well-known is that more than ten thousand women traveled to Washington, D.C., to lend their minds and their hard-won educations to the war effort. The recruitment of these American women – and the fact that women were behind some of the most significant individual code-breaking triumphs of the war – was one of the best-kept secrets of the conflict. The military and strategic importance of their work was enormous.

They were recruited with various methods for several stations connected to either Army or Navy. Many ended up at D.C.’s Arlington Hall, headquarters of the Army’s Signal Intelligence Service, its cryptography division. It’s true that the government went to great lengths to preserve secrecy around its code-breaking endeavors, putting the participating women under gag orders for decades. Coz quoted above wasn’t far off in her assumption that leaking what her work entailed would result in punishment as severe as death.

The women were told that just because they were female, that did not mean they would not be shot if they told anybody what they were doing. They were not to think their sex might spare them the full consequences for treason in wartime.

Recently, there’s been a wave of nonfiction exploring and celebrating the contributions made by women, previously unrecognized or not widely known, to major milestones in American history, particularly around this time period. The Girls of Atomic City is another “untold story” of women who helped win the Second World War, by enriching uranium for atomic bombs. Hidden Figuresadapted into a lauded film, highlights the African-American NASA mathematicians who helped advance the U.S. space program. The Radium Girls covers the women who painted clock faces with glowing radium in the 1920s, poisoning themselves in the process.

Embarrassing confession: I haven’t read any of these. What kind of nonfiction reviewer who loves women’s stories am I?! They’re all on my list, I just hadn’t cracked any yet (have you?) but Code Girls was an inspiring, fantastic entry into this important, overdue genre.

It’s fascinating from start to finish, without a single dull moment like those that too often characterize history books. Mundy covers all the bases: we learn about the women, their backgrounds, personal lives, and work (even code breaking nitty-gritty), how it all fits into cultural and wartime contexts, and how their exhaustive efforts affected and were incorporated into military schematics. Then there’s the development of code breaking itself, and women’s pivotal role.

One prominent woman involved, Elizebeth Friedman, was one of the few with cryptography experience prior to being recruited. She’d worked on breaking codes used to ship alcohol into America during Prohibition, when it was legal to drink but illegal to get, essentially. Mundy explains this shipping (called rum-running) was similar as a lucrative business to modern drug cartels, and Friedman was active in Coast Guard law enforcement, deciphering rumrunner messages.

Friedman had taught them during their training…that you can break a foreign cipher without understanding the language, as long as you know how the letters in that language behave. Certain letters, like S, often travel alongside certain other letters, like T…

Even this methodology, explained in evolving forms as the enemy changes tactics, is completely fascinating and never dry. The American women’s work is also influenced by the work done by British and Australian cryptographers, and we get lots of details on how the Allies aided one another, like on the infamous German Enigma machine.

One male cryptanalyst, the Yale-educated Frank Raven, brought into the Navy’s office of cryptanalysis, engaged in one of the dramas that often enveloped this kind of work. There was little squabbling or backstabbing over promotions or pay, rather competition over who could find the correct solution the fastest – all that mattered in wartime. Arriving “spoiling for a fight,” he eventually brought about the downfall of brilliant mathematician and fellow cryptanalyst Agnes Driscoll, one of the women whose story appears consistently throughout the book and who’s recognized as one of the best cryptanalysts ever.

She devised a solution for cracking the Enigma machine, but the technology of the day wasn’t adequate for carrying out her solution in a timely way. Bitter, jealous, and seemingly strangely angry that Driscoll had returned to work after a car accident, Raven broke into her safe and intercepted messages she was working on to try and one-up her and learn from her progress. It resulted in her being demoted for not developing the deciphering machine that he did, forcing her into a kind of obscurity despite her brilliance in the field.

In a postwar oral history, Raven said of Aggie:

In retrospect I am convinced that Aggie Driscoll is one of the world’s greatest cryptanalysts. I am convinced that the same accident that moved her from a beautiful woman to a hag affected her mind and that when she came back she couldn’t solve a monoalphabetic substitution. 

Mundy comments, “Nobody knows how Agnes Driscoll felt. Nobody bothered to take an oral history from one of the greatest cryptanalysts in the world.”

This was just one example of the towering sexism these women faced not only during their work, but in what should have been a shining legacy. Even postwar, after their wartime offices transitioned into the peacetime National Security Agency, these women were pushed from the spotlight, forced or encouraged to stay silent.

Driscoll’s is far from the only story here of women subjected to comments about their appearance and the nature of their work. They didn’t have to lie much about what they were doing, since others didn’t require great convincing to believe they were just cleaning offices and sorting paperwork.

Ann Caracristi, another frequent subject, became first female deputy director of the NSA, “the federal entity the wartime code breakers begat.” Their legacy is truly remarkable. Stories like Caracristi’s and Driscoll’s are extensively told, while other women get less detailed portraits. But’s it’s all fascinating, and Mundy has done such thoroughly researched work that I always felt like I was learning so much. Despite the wealth of information it packs in, it’s so wonderfully written, completely understandable and accessible for non-technical types and without prior knowledge of the era’s history. It’s as well-paced as a great novel.

The only con was that it frequently skipped around in time and location, leaving me a little disoriented until I could identify the period and why the jump was made, but it remained confusing. Otherwise, it’s an extraordinary work.

Virtually as soon as humans developed the ability to speak and write, somebody somewhere felt the desire to say something to somebody else that could not be understood by others.

Enlightening, always engaging, and long overdue history of the hard-working, admirably intelligent women who aided the Allied war effort so significantly. If only every history book were written as compellingly and beautifully as this one.
Rating: 4.5/5

Code Girls:
The Untold Story of the American Women Code Breakers of World War II
by Liza Mundy
published October 10, 2017 by Hachette

I received an advance copy from the publisher for unbiased review.

Book Depository


16 thoughts on “Ladies of Cryptography: The Women Who Broke War’s Codes

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  1. I didn’t know the Radium Girls were also covered in The Poisoner’s Handbook, I’ve had that one on my TBR for awhile, good to know! I really recommend Code Girls, it’s something special – so well-written for how much information it covers.


    1. Thank you! I’m happy to hear that, because sometimes I feel like I read and post too much from the same genres. This was such an enlightening read, I highly recommend it and hope you get to it too!


  2. I’ve been wanting to read this book since it came out. Didn’t get a chance to read Hidden Figures but the movie was fantastic! Thanks for the review!

    Liked by 1 person

    1. I have to check that one, I was initially hesitating about the book because math isn’t my strong suit at all and I was afraid it’d be too mathy for me to really enjoy or appreciate. Code Girls is phenomenal, I completely recommend it. Looking forward to hearing your thoughts if you get to it!

      Liked by 1 person

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