Code Girls by Liza Mundy

This is a wonderfully researched book that brings well-deserved recognition to the American women who worked on breaking enemy codes during World War 2. Because it was so secret and remained so many years after the war, their work went largely unacknowledged until recently.

The Navy largely recruited from northern women's colleges like Vassar, Wellesley, and Smith, looking for young women studying languages and math. The Army competed for talent by going to rural towns in the South, and found many young schoolteachers. The sociological aspect is fascinating on its own: all these young women leaving their homes, colleges, and families to live in Washington D.C. for war work that they couldn't discuss with anyone. They had to tell people they were secretaries, sharpening pencils and emptying trashcans.

The prewar work of exceptional women who pioneered the field of cryptology and cryptanalysis forms the background for what came after, and Mundy describes the methods of both code-makers and code-breakers for those who can follow the puzzling craft.

Mundy's writing is very engaging, and her epilogue at the end, telling what happened to many of the featured women in the book is very moving. She interviewed as many of the women as she could find, many of whom still found it difficult to talk about their work because secrecy was so ingrained in their experience.