Code Girls: The Untold Story of the American Women Code Breakers of World War II

Summary of Code Girls

1. 1

   The Secret Female Army That Changed the Course of WWII

   

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   While Rosie the Riveter became the iconic symbol of women's wartime industrial contributions, another group of women worked in the shadows, their impact immeasurable. Over 10,000 young women-college students, teachers, and mathematicians-were secretly recruited to Washington D.C. to break enemy codes. Their work was so crucial that military leaders later estimated it shortened World War II by at least two years. These women came from elite colleges like Wellesley and Smith, but also from teaching positions in small towns across America. What made them particularly valuable was their educational background-training in languages, literature, music, mathematics, and meticulous attention to detail. They passed rigorous security clearances and were sworn to absolute secrecy, unable to tell even their families about their vital work. By war's end, women constituted nearly 70% of the Army's code-breaking force and 80% of the Navy's domestic cryptanalysts. Their story remained largely untold for decades, their contributions unacknowledged until recently, when the NSA finally began recognizing these remarkable women who helped win the war through the power of their minds.

2. 2

   The Mysterious Recruitment That Changed History

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   In late 1941, women's colleges across America received cryptic letters. At Wellesley, Professor Helen Dodson screened candidates with two questions: Did they enjoy crossword puzzles? And were they engaged? The Navy targeted elite women's colleges for students skilled in languages and mathematics, while the Army recruited from teaching colleges in the South and Midwest. Pearl Harbor's attack intensified the drive to staff America's cryptanalytic operations. The women worked in absolute secrecy, studying frequency analysis and cipher systems without revealing their role to anyone. Though only 4% of American women had completed college by 1942, these recruits - disciplined graduates who easily obtained security clearances - possessed ideal skills for code breaking. Their critical work saved countless lives, though most remained unrecognized.

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   The Pioneers Who Broke the Glass Ceiling

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   America's early cryptanalytic capability was built by brilliant women, not men. Most were former schoolteachers seeking greater intellectual challenges. Elizebeth Smith, an English major with classical language training, joined Riverbank Laboratories in 1916. There, she and future husband William Friedman established America's first cryptanalytic training school during WWI. While William later joined the Army Signal Corps, Elizebeth broke rum-runners' codes during Prohibition. Agnes Meyer Driscoll, a mathematics teacher who enlisted during WWI, became the Navy's cryptanalytic cornerstone. As a civilian, she tested enciphering machines and broke Japanese naval codes, training many of the code breakers who became crucial in WWII. Though underpaid compared to men, these women's success created a "jackpot effect" - women hiring and mentoring other talented women - establishing a foundation for thousands who would contribute during WWII.

4. Chapter 4

   From Classroom to Code Room: Dot Braden's Journey

   In September 1942, twenty-two-year-old Dot Braden was teaching multiple subjects at Chatham High School in Virginia for $900 a year. With male teachers at war and female ones leaving to marry soldiers, she reached exhaustion by Christmas. Born in 1920, Dot was the oldest of four children raised by a single mother during the Depression. After excelling in college French and Latin, she accepted government recruiters' offer of classified war work in Washington, D.C. - at nearly double her teaching salary. Arriving at Arlington Hall in October 1943, Dot found a former girls' school converted into a secure facility. After signing secrecy oaths, she was directed to Arlington Farms, a women's dormitory complex nicknamed "Girl Town." Inside Arlington Hall, the world's largest clandestine message center bustled with women working at tables equipped with graph paper, tabulators, and specialized typewriters. Thousands of civilian women decoded enemy messages from across the globe. Dot later moved to Fillmore Gardens with friends Liz and Ruth "Crow" Weston. Though they sometimes worked on the same Japanese Army code-breaking effort, they never discussed their work - maintaining their secrecy oaths even among themselves.

   Chapter 5

   Breaking the Unbreakable: The Purple Machine

   On September 20, 1940, Genevieve Grotjan cracked Japan's most sophisticated diplomatic cipher system, the Purple machine. While the British, Germans, and U.S. Navy had deemed it impossible, William Friedman's team persisted, theorizing the machine used telephone-like stepping switches to transform letters. Grotjan, a junior mathematician, discovered the crucial "twenties" pattern that had stumped everyone else. The breakthrough left Friedman emotionally overwhelmed - the work's intensity later led to his three-month hospitalization in 1941. He deemed it "the most difficult cryptanalytic problem successfully handled by any signal intelligence organization in the world." The team had reconstructed an enemy cipher machine without seeing it. This breakthrough became the Allies' most valuable intelligence source. Japanese diplomats, especially Ambassador Oshima in Berlin, provided detailed reports about Nazi activities and German military preparations. These "Magic" intelligence briefings proved crucial for Allied strategy, including D-Day planning, while women like Grotjan rose to positions of significant authority.

   Chapter 6

   From Defeat to Victory: Turning the Tide in the Pacific

   Early 1942 marked America's darkest period, with Japan's navy controlling a quarter of the Pacific Ocean and capturing territories from Guam to Burma. After MacArthur's retreat from the Philippines, Corregidor fell to Japanese forces. In the Atlantic, German U-boats conducted their "Happy Time," sinking ships near American shores. The challenge became twofold: replacing ships and breaking the Germans' Enigma codes. The Navy expanded its code-breaking operation from 60 to 720 personnel, largely recruiting educated women who worked exhausting shifts in difficult conditions, knowing sailors' lives depended on their work. The turning point came in May 1942 when decoded messages revealed Japan's plans for Port Moresby. Later, when intercepted messages mentioned target "AF," code breakers confirmed it was Midway by having the base broadcast a fake water shortage. This intelligence led to Admiral Nimitz's decisive victory at the Battle of Midway in June 1942 - halting Japan's expansion and beginning America's Pacific advance.

   Chapter 7

   The Legacy That Outlived the War

   As Arlington Hall decoded Japan's surrender message in August 1945, Dot Braden and her colleagues raised their hands in oath, knowing the war's end before the world did. When Truman announced Japan's surrender, code breakers joined Washington's euphoric street celebrations. People rode atop cars while toilet paper streamed from hotel windows. During these festivities, code breaker Jeuel Bannister met her future husband. Many women, including Dot, left to marry returning veterans. Dot and Jim Bruce settled in Richmond amid housing shortages. Her friend Crow worked at Arlington Hall until her first pregnancy - reflecting postwar attitudes toward working women. Their friendship remained so close their children thought they were relatives. Some women continued at the NSA. Ann Caracristi became its first female deputy director, while Gene Grabeel led the Venona project targeting Soviet communications. Though women comprised 90% of that workforce, many talented analysts departed upon starting families, and women struggled for recognition into the 1980s. Dot kept her code-breaking work secret for fifty years. When she finally shared hints, her family was skeptical. Even now, with NSA's permission to share her story, she instinctively guards certain details - embodying the dedication of thousands who quietly shaped history through their intelligence work.

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