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14 min 33 sec
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Code Girls: The Untold Story of the American Women Code Breakers of World War II

Liza Mundy tells how thousands of American women, hired because code breaking looked tedious, helped read Japanese and German messages, helped mislead Germany before D-Day, and were then left out of the war's official story.

Table of Content

When World War II ended, women accounted for over 80 percent of the code breakers working for the US Navy on the home front, and 70 percent of those working for the army. Hardly anyone knew. In Code Girls, journalist Liza Mundy recovers the story of an estimated 11,000 American women who cracked enemy codes, and wrote misleading ones, from Washington and Virginia.

Her case is that these women were hired because the work looked tedious and women were thought patient. They turned that low expectation into victories from the Pacific to Normandy. Then secrecy and sexism wiped them from the record for decades.

The story explains, in plain terms, how a code gives way to a stubborn mind. It also trains a sharper eye for talent that hides in plain sight, including the uncredited work happening on your own team.

A millionaire hunting for a hidden confession in Shakespeare and a math teacher facing a Japanese code made only of numbers started American code breaking. Both stories turn on a mistaken idea about who suits the work.

Recruiters went looking for code breakers at elite colleges and in small-town hotel lobbies, and they asked odd questions about puzzles and fiances. The questions they chose reveal what they wanted, and what they assumed about women.

A would-be math professor who could not find a university job walked up to her boss with a stack of worksheets. What she had noticed changed what America could hear for the rest of the war.

The Japanese Army’s code had beaten every expert who tried it. The unit that finally broke through was led by a twenty-three-year-old English graduate, and the reason she got the job matters for any team.

Before the Normandy landing, American women sent coded messages they never intended the Germans to decipher. The real weapon was something else in the airwaves, and a later estimate counted thousands of lives it saved.

Dormitories for thousands, cheap train tickets and letters to five soldiers at once made wartime Washington thrilling. Then a lieutenant decoded a warning about her own brother’s ship, and could do nothing with it.

An army officer publicly thanked the code breakers who shortened the war and left out one fact about most of them. For one veteran, that omission helped cost her a place in architecture school.

Code Girls is, finally, a story about what an assumption can hide. The officials who hired these women thought the work was dull and suited to patient minds. Patience turned out to be the smallest part of what these women brought. It let Genevieve Grotjan see a repeat the men had missed, let Ann Caracristi rebuild codebooks nobody could crack, and let a building full of women read every Japanese Army message. Then the secrecy that made them effective made them invisible, until a journalist had to petition the government for their story.

The book also leaves habits worth keeping. When a colleague is praised only for being careful or reliable, look harder at what that care produces. When an organization runs smoothly, ask whose work never made the record, and add it. When a problem looks random, take Friedman’s advice and wait for the pattern to return.

Elizabeth Bigelow could never tell an architecture school what she had done for her country. Mundy’s book finally says it for her, and for thousands like her.

About this book

What is this book about?

In the 1930s an educated American woman could expect to become a schoolteacher, and little else. World War II changed that for more than 10,000 of them. Recruiters found them at elite colleges and in small towns, and one Wellesley senior was asked in her interview whether she liked crossword puzzles. The women moved to Washington and Virginia to break enemy codes, and by the war's end they made up most of the military's code breakers at home. Liza Mundy follows these women from the pioneers of the 1920s to the breaking of Japan's Purple cipher machine. She shows the Arlington Hall team that came to read every Japanese Army message, and the coded radio traffic that helped mislead Germany about where the D-Day invasion would land. She also shows life in wartime Washington, with its crowded dormitories, parties and letters to the front. Then comes the cost. Secrecy and sexism kept their work out of the record for decades and blocked some from the education promised to veterans. A few kept their silence into their nineties. Readers get a clear picture of how code breaking works, and the story of a talent that was overlooked even while it was winning.

Book Information

Rating:

Genre:

History

Topics:

Gender, War

Publisher:

Hachette

Language:

English, ไทย

Narrator:

Hannah

First published:

October 10, 2017

Pages:

448

Length:

14 min 33 sec

Get the book:

Amazon

Who it's for

  • Curious about WWII code-breaking

    Readers of World War II history who want the code-breaking story beyond Bletchley Park and Alan Turing.

  • Women in technical careers

    Women building careers in technical fields who want to know the pioneers who came before them.

  • Managers sensing unseen effort

    Managers who suspect their most careful, least praised people are doing more than anyone notices.

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About the Author

Liza Mundy

Liza Mundy is an American journalist and the New York Times bestselling author of five books. She is a former staff writer at The Washington Post and has also written about history, culture and politics for The Atlantic and Politico. Her other books include Michelle: A Biography, The Richer Sex, Everything Conceivable and The Sisterhood. Code Girls, published in 2017, tells the story of the more than 10,000 women brought in to break codes during World War II.

Ratings & Reviews

Ratings at a glance

4.6

Overall score based on 71 ratings.

What people think

Listeners find this account a gripping listen that shares an intriguing story of American women serving as code breakers in World War II. The book is meticulously researched and offers deep insights, rendering it essential material for history courses. Listeners enjoy the prose, with one noting it follows a simple-to-track narrative flow, and they consider it eye-opening for providing fresh viewpoints on the topic. Listeners applaud how the book depicts female empowerment, showcasing the incredible women who contributed to the code-breaking operations.

Top reviews

Anucha

Wow, what an incredible tribute to the thousands of women whose contributions were literally kept secret for decades. Liza Mundy has crafted an engrossing narrative that shines a much-needed light on the female mathematicians and teachers who were the backbone of American cryptanalysis during WWII. It is shocking to realize how these heroes were almost erased from our history books simply because of their gender and the classified nature of their work. The book is meticulously researched, using declassified documents to bring women like Dot Braden to life in a way that feels both personal and monumental. I was particularly moved by the descriptions of their dedication, working long hours in sweltering D.C. offices while being told to tell their families they were just doing secretarial work. This is female empowerment at its finest. If you enjoyed The Imitation Game, you absolutely must read this to see how the American side of the operation functioned. It’s an enlightening, required read for anyone interested in the real stories behind the Allied victory.

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James

As someone who has always loved math and history, I found Mundy’s account of these 'human computers' absolutely riveting. It’s rare to find a non-fiction book that manages to be both educational and deeply emotional at the same time. The scale of the operation—over ten thousand women—is mind-blowing. These women weren't just 'helping'; they were essential to the victory. I was especially struck by the chapter on Elizebeth Smith, whose story alone deserves a whole movie. The author does a great job of explaining the high stakes and the immense pressure these young women were under. Some parts are heart-wrenching, especially when you realize how many of them had to return to 'ordinary' lives and never speak of their achievements. This book isn't just a history lesson; it's an act of justice for these women. I’ve already recommended it to everyone in my book club!

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Nadia

Liza Mundy has done an extraordinary job digging through declassified documents to piece together a history that was almost lost to time. I was completely gripped by the stories of these women who were recruited from small towns and elite colleges alike to perform work that changed the course of the war. The writing is clear and the pacing is excellent for a history book. It really gives you a flavor of what life was like during the 1940s—the secrecy, the patriotism, and the sudden shift in societal roles. Seeing how these women proved their intellectual worth against the prevailing stereotypes of the time was incredibly satisfying. I also loved the updated version which includes stories from readers who discovered their own family members were 'code girls.' It’s a beautiful, essential piece of history that finally gives these ladies the recognition they deserve.

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Sureerat

Picked this up because my grandmother used to hint at 'government work' she did in D.C. during the forties, and this book felt like reading her secret history. It is a stunning, emotional look at a generation of women who were told to do the impossible and then never talk about it. Mundy captures the spirit of the era perfectly—the urgency, the fear, and the incredible brilliance of these young women. The book is packed with fascinating facts and personal stories that make the history feel alive. It’s more than just a book about codes; it’s a book about what women are capable of when given the chance to lead. I actually shed a few tears during the conclusion when discussing the legacy of these women. Truly an awe-inspiring read that everyone should have on their shelf. We owe these women a debt of gratitude that can never be fully repaid.

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Parichat

Finally got around to reading this after seeing it on so many history lists, and for the most part, it lived up to the hype. Mundy provides a very detailed account of the recruitment process from the Seven Sisters colleges and the grueling training these women underwent to break Japanese and German codes. The writing style is generally easy to follow, making complex military history feel accessible to a layperson. I found the sections on the impact of their work on the Pacific Theater especially fascinating. However, I’ll admit the book felt a bit bogged down in the middle with what I’d call domestic fluff. There’s a lot of focus on their living arrangements, train rides, and social lives that occasionally distracted from the actual codebreaking. Still, the overall message of female brilliance and patriotism is powerful. It’s a solid 4-star read that fills a massive gap in our understanding of the war effort.

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Preeda

Ever wonder what thousands of college-educated women were doing while the men were off at the front during World War II? This book provides a fascinating answer that goes way beyond the 'Rosie the Riveter' trope we all know. Mundy explores how the Army and Navy recruited women with backgrounds in Latin, Greek, and mathematics to tackle the most difficult codes of the era. The narrative style is engaging, and it brings a totally new perspective to the subject of wartime intelligence. I liked how the book balanced the big-picture military successes with the personal struggles of the women, such as facing sexism in a male-dominated environment. My only minor gripe is that the chronology can be a bit wonky, jumping back and forth between WWI and various recruitment phases. Regardless, it is an eye-opening read that makes you appreciate the grace and intelligence of the women who helped win the war.

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Emily

After hearing about The Imitation Game for years, it was refreshing to finally get the American side of the story told so vividly. This book is a carefully researched account that brings a new perspective to WWII history. It’s not just about the geniuses at the top; it’s about the collective effort of thousands of women working behind the scenes. The book is written in an easy-to-follow style that makes you feel like you're right there in the hot, cramped offices with them. I found the parts about Vint Hill and the various naval bases particularly interesting as they provided a local context I hadn't heard before. While there is a lot of information to digest, the author does a good job of keeping the human element at the forefront. It’s a great read for anyone who loves learning about the 'hidden' figures of history.

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Nina

The truth is, I had very mixed feelings about this one despite my interest in the subject matter. On one hand, I applaud the author for highlighting these unsung heroes who saved countless lives through their tireless efforts. On the other hand, the structure felt incredibly disjointed. It often read like a collage of hundreds of different people, where a 'Jane Doe' is introduced for two paragraphs and then never mentioned again. This made it difficult to form an emotional connection with anyone other than a few main figures like Elizebeth Smith. To be fair, the research is exhaustive, but the sheer volume of names and domestic details—like what they ate or who they were dating—surrounded the actual work with too much filler. I was hoping for a more technical deep-dive into the cryptanalysis itself. It’s an important historical record, but as a narrative, it frequently loses its momentum.

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Selin

Look, this book is undoubtedly important for the historical record, but the execution felt a bit uneven at times. I appreciate that the author wanted to give every woman she found in the records her moment in the sun, but it led to a recitation of names that became hard to track. I’d find myself interested in one person’s journey, only for the chapter to end suddenly and shift to a different group entirely. It felt a bit disjointed, like a series of essays rather than a smooth narrative. To be honest, some of the technical parts about how the codes were set up were a bit over my head, though that might just be my lack of math skills! While it’s an enlightening look at female empowerment and the war effort, it requires a bit of patience to get through the slower sections about their domestic lives.

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Mia

Not what I expected based on the title and the glowing blurbs I had seen online. I went into this expecting a heavy focus on the actual decoding operations and the mechanics of how they broke the Japanese 'Purple' code. Instead, I found myself wading through endless pages about train rides, letters to boyfriends, and what the women wore to dances. It felt like a collection of anecdotes that never quite coalesced into a compelling story. Much of the book was repetitive, constantly hammering home the point that women were important without giving enough detail on the 'how.' Honestly, it was one of the most boring non-fiction books I’ve picked up in a while. I appreciate the research, but it could have been half the length and twice as effective. If you want a technical look at cryptology, this isn't it. It’s more of a social history of young women in D.C. during the 1940s.

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Questions about this book

It tells the story of an estimated 11,000 American women who broke and wrote codes for the US Army and Navy during World War II. Drawn from colleges and small towns, these women accounted for over 80 percent of the navy’s code breakers stationed at home, along with 70 percent of the army’s. Mundy follows their breakthroughs against Japanese ciphers, their part in the deception before D-Day, and how secrecy and sexism hid their work for decades.

William Friedman’s civilian team in the army’s Signal Intelligence Service attacked Purple with cribs, partly from messages Tokyo also sent in an older system the Americans could already read. On September 20, 1940, code breaker Genevieve Grotjan spotted where the pattern repeated, something her male colleagues had missed. That let the Americans build a working Purple machine without seeing the original, and the Allies read Purple traffic for the rest of the war.

In two ways. WAVES at Sugar Camp in Dayton, Ohio, built more than 100 bombe machines used against German Enigma messages, and intelligence from Enigma and Purple helped steer planners toward Normandy. Then, for Operation Bodyguard, army and navy women wrote coded messages on the SIGABA machine so German listeners would conclude the main landing was coming at the Pas de Calais. A later estimate said the surprise saved 16,500 Allied lives.

Secrecy and sexism, in Mundy’s account. When army officer Stephen Chamberlin publicly credited code breakers with saving thousands of lives, he did not mention that more than 10,000 were women. Much of the record stayed classified for over 70 years until Mundy petitioned for its release. Unable to describe their service, some navy veterans missed GI Bill education, and Elizabeth Bigelow was rejected by three architecture schools saving places for veterans.

The story suggests that talent often hides in work labeled tedious, as it did for women hired mainly for their patience. Arlington Hall shows what happens when ability decides who gets the hardest problem, whatever someone’s rank: a twenty-three-year-old English graduate led the unit that helped crack the Japanese Army’s codes. And the women’s long silence shows how easily uncredited contributions disappear unless someone records them.

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Code Girls

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