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

by Liza Mundy

During rest periods, the women would put their heads down on the worktable, and the officer in charge, a former schoolteacher named Dot Firor, would read aloud from The Bobbsey Twins or Little Women or some other comforting storybook narrative, and give them twenty minutes to let their minds drift. On the graveyard shift, some would sing to stay awake as they soldered. There was a woman from an Irish family, Pat Rose, who would sing “It’s the Same Old Shillelagh” in the most beautiful lilting soprano.

It wasn’t just a matter of getting the math to work; it was a matter of getting the machinery to run. The bulky bombes, which stood seven feet tall and ten feet long and weighed more than two tons, had hundreds of moving parts, and even a bit of copper dust could foul the works. “The design of the Bombe eventually required material and components from some 12,000 different suppliers,” noted one memo. Some components did not exist on the commercial market and had to be designed and made. The designers needed diodes, miniature gas tubes, high-speed commutators, and the carbon brushes the wheels would come into contact with. As the women in Building 26 wired commutators, the staff in NCR’s Electrical Research unit swelled from seventeen in August 1942 to eight hundred in May 1943, building the machines and perfecting the design.

The people working on the Enigma project were mathematicians and engineers. They were precise, conscientious people who liked to solve problems and build beautiful things, not kill people. The work was hard on the women as well, particularly those like Louise who knew the stakes.

Everybody became an old salt pretty quickly. After just six months in the Navy, the young women who had wired the commutators—and now were running the bombes in Washington—found themselves supervising women even younger and greener than they were, many of them eighteen-year-olds fresh out of boot camp at Hunter College.

As Jimmie Lee and the other women settled into their duties, they became part of an Enigma code-breaking chain that was virtually all female. When a message arrived at the Annex, it would first go to the cribbing station. The cribbers had one of the hardest jobs, sifting through intelligence from the war theater, including ship sinkings, U-boat sightings, weather messages, and battle outcomes. Scanning intercepts, they had to select a message that was not too long—a long message might involve more than one setting—and guess what it likely said.

From there, the menu would be passed to Jimmie Lee or another bombe deck operator. If there was a hit, it would go to somebody like Margaret Gilman, from Bryn Mawr, who would run it through the M-9 to see if the “hit” produced coherent German. Once they got a key setting, subsequent messages for that day could be run through the M-9 and translated, without having to use the bombes. Soon, the operation was so smooth that most keys were obtained in hours and most messages decrypted immediately.

“Since 13 September 1943, every message in that cipher has been read and since 1 April 1944 the average delay in ‘breaking’ the daily key has been about twelve hours. This means that for the last half of each day, we can read messages to and from Atlantic and Indian Ocean U-boats simultaneously with the enemy. In fact, during these hours the translation of every message sent by a U-boat is at hand about twenty minutes after it was originally transmitted. At present, approximately 15 percent of these keys are solved by the British and the remainder by OP-20-G.”

At another desk, several other Goucher women, including Jacqueline Jenkins (later the mother of Bill Nye, aka Bill Nye the Science Guy), tracked “neutral shipping” based on daily position reports. Neutral shipping mattered because if those ships deviated from their assigned sea lanes, it might mean they were surreptitiously supplying U-boats.

After the carnage of 1942 and early 1943, the Allies had seen a stunning turnaround in the Atlantic. By September 1943, most U-boats had been swept from the Atlantic waters. This was thanks not only to the new high-speed bombes but also to a host of other Allied war measures: advances in radar, sonar, and high-frequency direction finding; more aircraft carriers and long-range aircraft; better convoy systems.

There was always the chance, however, that the U-boats could come back. And they did try. In October 1943, the U-boats reappeared. But now the costs were punishingly high. For every Allied merchant vessel sunk, seven U-boats were lost.

In May 1944, the Allies sank half the U-boats in operation—more than the Germans could replace. More than three-quarters of the U-boat crews were killed, suffering terrible watery deaths. The women in the tracking room were privy to the full immensity and horror.

One unit of women bird-dogged the American military units to make sure their radio traffic did not reveal too much about their whereabouts. The women intently studied the flow of U.S. military traffic to make sure that the Allies were not revealing the kinds of things that the enemy was revealing to them. They made charts and graphs to study American communications in specific regions, at specific times, during specific conflicts and events, to see what—if anything—might have been disclosed to the enemy. And they studied the characteristics of certain circuits. These same skills enabled the WACs to create dummy traffic: fake radio traffic that so exactly resembled real American traffic that it persuaded the enemy that the fictitious units existed and were on the move.

Exactly as Churchill described, the effect was to create a bodyguard, or protective area, around troops or leaders. In the Pacific theater, when a real attack was planned against Guam and Saipan, Arlington Hall created fake traffic to divert Japanese attention to Alaska. They created fake traffic to enable the deployment of the Fifth Infantry Division from the Iceland Base Command to the United Kingdom. They used fake traffic to disguise movements to and from the Yalta Conference.

The women analyzed Allied traffic, so as to be able to convincingly re-create a fake version of it. The calculations unit worked to determine “the various circuit characteristics, such as group-count frequency distribution, percentage in each precedence and security classification, filing time distributions, address combination, and cryptonets employed for each station of which the traffic is to be manipulated,” as one report put it.

Once created, fake traffic had to be routed. The women had to create a plausible schedule; release prearranged dummy traffic to be transmitted during times when such traffic might be expected; maintain circuit flow; and monitor what went out. They had to understand the circuits, the call signs, the frequency, the peak volume times: everything.

The Allies began sending out dummy traffic months before the D-Day landing, as Patton’s fictitious Army traveled around England and began to gather. Meanwhile, the double agents were hard at work communicating with Germany, ably encouraging the notion that FUSAG was poised to assault the Pas de Calais.

On June 1, 1944, the tireless and always obliging Baron Oshima crafted a message to Tokyo and sent it over the Purple circuit. The encrypted message revealed that Hitler, anticipating an Allied invasion, expected that diversionary landings would take place in Norway and Denmark and on the French Mediterranean coast. Oshima added—and this was crucial; this was exactly what the Allies had hoped—that the Führer expected the real Allied attack, when it came, to come sailing through the Strait of Dover, toward the Pas de Calais.

D-Day was a great achievement. They knew that. But somehow it did not seem cause for celebration, or not exactly, or not yet. Going to church was the only way they could think of to honor the tragedy and loss, which they sensed though they did not yet know the full extent: the Allied soldiers bobbing facedown in the water, drowned under their packs; the Rangers shot down as they dug handholds with their knives to scramble up the cliffs; the bodies on the beaches; the pilots who crashed in the fog and the smoke; the parachutists who drowned in marshes. It was the only way they could think of to honor the men who had made this sacrifice. Ann would remember the Normandy invasion as one of the great moments of the war, and she would remember her wartime code-breaking service as the great moment of her life. But for now, all she could do was pray for the souls of the dead.

“The invasion has caused a great increase in the amount of our traffic,” read the daily log for OP-20-GY-A-1. “A great quantity of administrative traffic, representing several circuits, has appeared.”

There was so much loss even amid the victories. Ten months after D-Day, in April 1945, President Franklin Roosevelt died. The women cried like babies. There was a funeral procession when the president’s body was brought to Washington from Warm Springs, Georgia, and much public mourning, and the WAVES marched in a parade to honor him. People wondered whether the new president, Harry Truman, would be up to the job. Some of the women made individual trips to the White House, standing at night in the eerie quiet of Lafayette Square, where the sound of water dripping from the trees was the only noise, along with the changing of the guard.

In many ways the waning days of the war were the bloodiest and worst. In both war theaters, Axis leaders resolved to make any Allied victory as costly as possible in terms of lives lost.

The postwar U.S. government made this clear. There was no more state-sponsored child care. In a postwar, Cold War America, child care was viewed with suspicion, as the kind of thing communists used to raise their children collectively. The U.S. government began doing the opposite of its wartime recruiting; it made propaganda-type films telling women it was important to leave their jobs, return home, and tend their households. The films pointed out that it was unnatural for women to be breadwinners, taking jobs from men. Quitting one’s job became a matter of patriotism. And so, many of the wartime women workers did leave their jobs when they had children. Among them was Crow, even though she very much liked what she did.

Both women grew bored at home and went back to work when their children were old enough. Dot became a real estate agent. Crow, still living in Arlington, took a job as a cartographer with a transportation consulting agency. Crow loved maps, and she loved her work. She also worked the polls every Election Day, honoring the patriotism and sense of civic duty that her father, back in Bourbon, Mississippi, had instilled in her. That day of commitment to democracy remained sacred to her.

By far the majority of women at Arlington Hall packed up and went home after the war. Even many of the top women, among them Delia Taylor Sinkov and Genevieve Grotjan Feinstein, at some point stopped working. Often this occurred when they began having children. Motherhood was the dividing line between brilliant women who stayed in the work and those who did not. For a woman with children, there were few resources to make a career feasible. The nation lost talent that the war had developed. The 1950s and 1960s would not bring another critical mass of women to succeed the wartime code breakers, and in the 1970s and 1980s, women at the NSA would have to fight a battle for parity and recognition all over again.

For the women who left the field but wanted to continue working or studying, postwar opportunities were mixed. Women who served in the U.S. Navy qualified for the GI Bill, at least in theory. For returning servicemen, the GI Bill was a life-changing benefit that put college within reach for middle-class men. For the Navy women, however, their experience of GI benefits was hampered by the old idea that women are not suited for the highest levels of learning.

In college, she shone in her mechanical drawing classes—as close to a drafting class as Vassar offered—and aspired to be an architect. Her professor was the legendary Grace Hopper, a computing pioneer who became a rear admiral for the Navy and helped develop the computer programming language COBOL. Elizabeth Bigelow always believed Hopper identified her for the code-breaking program. When Elizabeth got out of the Navy she applied to three leading schools of architecture. “In every case the response was the same,” she recalled later. “We’re sorry, but we are saving all our spaces for the men who have been in the armed services.” Elizabeth wrote back protesting that she had been in the WAVES for two years. She could not say she had sunk a convoy, because that was top secret. “The answers all came back, ‘We’re sorry, but no.’”

When they moved to Cincinnati, Elizabeth ended up running the computer system at the University of Cincinnati. ...

Edith was working at the Naval Annex when a recovered codebook was brought in, dripping wet, having been fished out of a sinking submarine by an alert American naval officer. After the war Edith stayed in the Navy for a while and was transferred to a hospital in New York where men with tuberculosis were being treated. One day, she was told that she was to receive her unit citation. She was to appear under the flag at nine a.m. “in full uniform with the ribbons to which I was entitled.” Since she had not purchased any, she had to find a male officer willing to lend her his. When she asked a young doctor, he said, “Only if I can come and look.” After the ceremony, the young doctor told her he was taking her to dinner. “It’s traditional,” he assured her. “Whoever you lend your medals to, you have to take to dinner.” There was no such tradition, and, reader, she married him.

Many of the code-breaking women helped advance the feminist movement—through their postwar employment, but also, sometimes, their postwar dissatisfaction. One woman I interviewed, whose mother worked at Arlington Hall, always sensed something was missing in her mother’s life, something she had had, once, and lost. This awareness, she said, “seeded feminism in our house.” But other women felt left out by the feminist movement. Erma Hughes Kirkpatrick, the bricklayer’s daughter, became a mother, housewife, and volunteer, and enjoyed it. She always felt feminism disrespected her contributions, even as her husband respected them. She started the first soup kitchen in Chapel Hill, North Carolina. “He and I were equals,” she said.

Her son Jim has always been intrigued by her wartime code-breaking service. As kids, he and his sisters used to go up in the attic and read the letters their dad wrote to their mother. His sentimental side was a revelation. But they never could get their mother to tell details about what she did. Now she has gotten the okay from none other than the NSA and has been assured that it’s fine to tell her story: The long-ago ban was lifted several decades ago. The government would like her to tell her story. But she still has her doubts. She cannot quite believe it.

Agnes Meyer Driscoll, a former Texas high school math teacher, became one of the great cryptanalysts of all time, cracking Japanese Navy fleet codes during the 1920s and ’30s. Courtesy of National Security Agency

Elizebeth Smith Friedman, another ex-schoolteacher, took a job in 1916 at an eccentric Illinois estate called Riverbank, where she helped found the U.S. government’s first code-breaking bureau. She later broke the codes of rumrunners during Prohibition. Courtesy of the George C. Marshall Foundation, Lexington, Virginia

Genevieve Grotjan aspired to be a math professor but couldn’t find a university willing to hire a woman. In September 1940, after less than a year as a civilian Army code breaker, she made a key break that enabled the Allies to eavesdrop on Japanese diplomatic communications for the entirety of World War II. Courtesy of National Security Agency

By 1940 only about 4 percent of women had completed four years of college, in part because many colleges would not admit them. Dot Braden, shown here as a girl with her nanny and brothers, was steered to Randolph-Macon Woman’s College by her spirited and determined mother. Courtesy of Dorothy Braden Bruce

Dorothy Ramale, shown here in her 1943 yearbook photo, grew up on a farm in Pennsylvania and wanted to be a math teacher. But the dean of women at Indiana State Teachers College called her in and told her the U.S. Army had another idea for her. Courtesy of Indiana University of Pennsylvania Special Collections

Women’s colleges in the 1940s were a mix of cerebral inquiry, marital ambition, and hallowed rituals. The 1942 May Court at Goucher College included Jacqueline Jenkins (fourth from left) and Gwynneth Gminder (second from right). Their lives changed when they received a secret summons from the U.S. Navy, as did Fran Steen, shown in the photo on the left. Courtesy of Goucher College Archives

Women rushed to enlist; one reporter described a WAAC recruiting station as a “tidal wave of patriotic pulchritude.” Women who tested high for intelligence and aptitude—and passed background checks—were routed into code-breaking service. Courtesy of U.S. Army INSCOM

Dot Braden worked at Arlington Hall, which before the war had been a girls’ finishing school complete with teahouse and lily ponds. It had been converted to a massive code-breaking facility that attacked the codes of Japan and many other nations, with more than seven thousand workers, most of them female. Courtesy of National Security Agency

The U.S. Navy, not to be outdone, took possession of Mount Vernon Seminary, a girls’ school in tony upper northwest Washington, D.C., adding hastily erected barracks to house four thousand female code breakers. Courtesy of D.C. Department of Transportation

At Arlington Hall, Ann Caracristi (far right), an English major from Russell Sage College, matched wits against Japanese code makers, solving message addresses and enabling military intelligence to develop “order of battle” showing the location of Japanese troops. The messages would then be passed along to Dot Braden and other women whose efforts led to the sinking of Japanese ships. Courtesy of National Security Agency

Also at Arlington Hall, a secret African American unit—mostly female, and unknown to many white workers—tackled commercial codes, keeping tabs on which companies were doing business with Hitler or Mitsubishi. Courtesy of National Security Agency

The Navy women broke enemy naval codes used across the world’s major oceans. Women formed the cryptanalytic assembly line that exploited the Japanese fleet code known as JN-25. They helped in the effort to shoot down the plane of Admiral Isoroku Yamamoto, architect of the attack at Pearl Harbor. “We really felt we had done something really fantastic,” said one, Myrtle Otto. “That was an exciting day.” Courtesy of National Archives and Records Administration

Women also ran the machines that attacked the German Enigma ciphers, maintained wall maps that kept track of U-boat locations and Allied convoys, and wrote intelligence reports that would be used by naval commanders. Courtesy of National Security Agency

During their off hours, the women wrote letters incessantly, sending the missives—often with an enclosed snapshot—to soldiers and sailors. One g-girl was writing twelve different men. Courtesy of Library of Congress

The women worked around the clock and often didn’t know whether to eat breakfast or dinner when they finished a shift. Navy code breaker Edith Reynolds (center), recruited from Vassar, relaxes with colleagues. Courtesy of Edith Reynolds White

At a top-secret building on the grounds of the National Cash Register Company (headquarters shown here), the women helped build more than one hundred “bombe” machines designed to break the German naval Enigma cipher. From the collections of Dayton History

Many women stayed friends for decades after their service. A group of Navy women kept a “round-robin” letter going for seventy years. The group included Elizabeth Allen Butler (front far left), Ruth Schoen Mirsky (front, second from right), and Georgia O’Connor Ludington (back, second from right). Courtesy of Ruth Mirsky

Dot and Crow’s friendship remained so strong that Crow insisted Dot and her husband, Jim Bruce, come to Washington to meet her own fiancé, Bill Cable, and give their stamp of approval before she would marry him. Jim Bruce is at right and Bill Cable is at left. Courtesy of Dorothy Braden Bruce

The women took their oath of secrecy so seriously that even now, at age ninety-seven, Dorothy Braden Bruce (shown here at her birthday party with her grandchildren) has trouble bringing herself to utter certain words she was told never to say outside the grounds of Arlington Hall. Courtesy of Dorothy Braden Bruce

How proud people are of their mother’s or grandmother’s or great-aunt’s service; how eager they were to tell their siblings, their children, to impress upon the family the import of what this foremother did. Phil Cagney wrote that his daughter, Erin, a grad student at American University, had walked by the former Naval Communications Annex (now the Department of Homeland Security) every day, without realizing that her grandmother, Mary V. Lauer Cagney, had run the bombe machines that broke the German Enigma cipher from that very place. “She’s literally walking in her grandmother’s footsteps,” he wrote.