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

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. —Jaenn Magdalene Coz, writing to her mother in 1945

It was not easy being a smart girl in the 1940s. People thought you were annoying.

But the pressure to marry was intense. At Wellesley, there was an entire page of the yearbook, the Legenda, devoted to a list of engagements (Mabel J. Belcher to Raymond J. Blair; Alathena P. Smith to Frederick C. Kasten) and naming women who had recently married (Ann S. Hamilton to Lieutenant Arthur H. James). The school in 1940 delivered a series of marriage lectures to its students, including one on “marriage as a career,” another on “biological aspects of marriage,” and others on “obstetrics” and “the care of the young child.” School lore had it that the winner of the senior class hoop roll—performed with much hilarity in cap and gown—would be the “class’s first bride,” and the winner was awarded a bouquet in recognition.

What the fuck is this even...

What is interesting about this generation of women is that they did understand that at some point they might have to work for pay. Forged by the Depression, they knew they might have to support themselves, even on a teacher’s salary, no matter how “good” a marriage they did or did not make. Some were sent to college with the idea that it would be ideal to meet a man, but their degree would permit them to “fall back” on teaching school.

And some women went to college because they were, in fact, ambitious and planned to compete for the few spots in law or medical ...

“They sucked us out from all over the country.” Secretaries were good at filing and record keeping and at shorthand, which is itself a very real kind of code. Running office machines—tabulator, keypunch—was a woman’s occupation, and thousands were now needed to run the IBM machines that compared and overlapped multidigit code groups. Music majors were wanted; musical talent, which involves the ability to follow patterns, is an indicator of code-breaking prowess, so all that piano practicing that girls did paid off. Telephone switchboard operators were unintimidated by the most complex machines. In fact, the communications industry from its origins was one that had been considered suitable for women.

It was a rare moment in American history—unprecedented—when educated women were not only wanted but competed for. Up to now, many college leaders had hesitated to encourage women to major in math or science, because jobs for women were so scarce. Soon after Pearl Harbor, however, companies like Hercules Powder started recruiting at places like Wellesley, looking for chemists. The Office of Strategic Services was avidly recruiting women, as was the FBI. The jobs landscape for female college graduates changed even just between 1941 and 1942.

The ballistics industry needed mathematicians to calculate weapon trajectories. Lever Brothers and Armstrong Cork also needed chemists. Grumman Aircraft Engineering Corporation needed “specifications men”—it used the same term for women—who could read blueprints.

MIT needed female graduate students to run its analog computers. The military services were competing with the private sector and with one another. It is true that this was seen as a temporary state of affairs and also true that sexism persisted: Educators worried that they might encourage women to pursue math and science who would then be left high and dry. One electrical company asked for twenty female engineers fro...

There are of course many reasons why the Allies prevailed in World War II—the industrial might of the United States, the leadership of military commanders and statesmen, the stoicism of British citizens who endured years of bombing and deprivation, the resistance of the French and Norwegian undergrounds, the cunning and resourcefulness of spies, the heroism of citizens who helped and harbored Jewish neighbors, and the bravery and sacrifice of sailors and airmen and soldiers, including the millions of Russian soldiers who bore the brunt of military casualties and deaths. But the employment of women also was one of these factors.

Women were more than placeholders for the men. Women were active war agents. Through their brainwork, the women had an impact on the fighting that went on. This is an important truth, and it is one that often has been overlooked. On the eve of Pearl Harbor, the U.S. Army had 181 people working in its small, highly secret code-breaking office in downtown Washington. By 1945 nearly 8,000 people would be working stateside for the Army’s massive code-breaking operation, at a much-expanded suburban Virginia venue called Arlington Hall, with another 2,500 serving in the field. Of the entire group, some 7,000 were women.

This means that of the Army’s 10,500-person-strong code-breaking force, nearly 70 percent was female.

By 1945, there were 5,000 naval code breakers stationed in Washington, and about the same number serving overseas. At least 80 percent of the Navy’s domestic code breakers—some 4,000—were female. Thus, out of about 20,000 total American code breakers during the war, some 11,000 were women.

PART I “In the Event of Total War Women Will Be Needed”

Dot didn’t know this, but she had found her way into the largest clandestine message center in the world.

Everywhere women were attacking enemy messages pouring in via airmail, cable, and teletype. The messages originated in Nazi Germany, Japan, Italy, occupied Vichy France, Saudi Arabia, Argentina, even neutral countries like Switzerland, sent between top political leaders and military commanders. At the Allied listening stations where the messages were secretly intercepted, American operators further encrypted them using their own encoding machines. Once they got to Arlington Hall, the messages had to be stripped of the American encryption before they could be stripped of the underlying enemy encryption. The whole thing was insanely complex.

Dot could see that there were thousands of people working here, in an operation fashioned after an assembly line. The ranks included a small number of Army officers and enlisted men, and some male civilians including older professors and young men with disabilities—some severe, such as epilepsy—that disqualified them for military service. But by far the majority were female civilians like Dot, and most of those, like Dot, were ex-schoolteachers.

Code breaking required literacy, numeracy, care, creativity, painstaking attention to detail, a good memory, and a willingness to hazard guesses. It required a tolerance for drudgery and a boundless reserve of energy and optimism. A reliable aptitude test had yet to be developed.

Temperament mattered, and here, too, was where the schoolteaching advantage came in. Officials were finding the best code breaker was a “mature and dependable” person with a “clear, bright mind”—but someone “young enough to be alert, adaptable, able to make adjustments readily, willing to take supervision,” and “able to withstand inconveniences of Washington.” This description fit many schoolteachers, including Dot Braden, to a T.

In America in the 1940s, three-quarters of local school boards (like telephone companies and other employers of female labor) had enacted a “marriage bar,” which required that married women not be hired and that a teacher must resign when she did marry, in accordance with the prevailing belief that a wife’s place was at home. By definition, then, many female schoolteachers were single.

Schoolteachers were smart, educated, accustomed to hard work, unused to high pay, simultaneously youthful and mature, and often unencumbered by children or husbands. In short: They were the perfect workers.

Based on these inquiries, investigators had submitted a “loyalty and character report” on Dot Braden. The report noted that she had a good college record and was of “the Anglo-Saxon race and of normal appearance.” She was found to be “native born,” as were her parents. The investigators noted that her parents were separated—her father was living at the Lynchburg YMCA—but said that they were “loyal citizens of middle-class.” The report concluded that Dot was “dependable and honest and of sober habits,” that she was “single and boards with her mother in a desirable section” of Lynchburg, and concluded that there was no reason to question her loyalty.

But even as the Arlington women were being educated and courted, they were receiving a subtle message that their very involvement in the war effort—these apartments they were renting together, the furniture they were buying, the meals they were cooking, their newfound independence—was creating troubling social changes. A talk by Charles Taft, titled “America at War,” centered on this idea. Taft, son of the late president William Howard Taft, now served as director of the Office of Community War Services, a new agency created to cope with the disruptions the Second World War was tearing in America’s social fabric.

He then launched into a speech in which the word “problem” appeared over and over. These problems, he explained, had been developing since the first new industrial plants were built in the United States in response to the bombing of England in 1939 and 1940. As Taft sketched it out, America now was one roiling mass of chaos. Factories and construction projects were drawing workers to communities that were hardly able to hold them. Minority groups were moving to find higher-paying work in places that had never seen them. Black churches from the South were moving entire congregations to California. New industries were setting up overnight, Taft said, without the infrastructure they required: schools, housing, playgrounds, hospitals. He talked about other changes in America’s quotidian rhythms. People were working around the clock, not just men but women too, and it was impossible to do chores in normal hours. “I send my washing home every week and I get it back every week,” confided Taft, whose family lived in Cincinnati. But even he had to contend with grocery shopping. “If you don’t provide some sort of extra night when you can shop out of hours, then you are going to find yourself with a serious problem.” But the main problem seemed to be—well, them. The women.

To deal with what he called the “child-care problem,” he said, the government had created a range of federally funded child-care options: “nursery school projects” for small children, aftercare for school-aged kids, and even home care, set up in boardinghouses, for infants. But American mothers were suspicious of child care, he lamented, because it was a “new idea” and nobody had ever offered it to them before. As a result, Taft said, children were running amok, and the government was sending social workers around to try to convince working mothers that putting their children in child care was better for everybody. “Of course, you have among mothers what is perhaps a very natural feeling, whatever trouble may be caused by little Willie, who is the neighbor’s child, that little Johnny, who is our child, doesn’t cause anybody any trouble.”

It’s possible to imagine the audience at this point uneasily shifting in their chairs, as Taft blamed their gender for much of the nation’s moral ills and social dislocations.

“Starting with some of the professionals, and then extending down among large numbers of amateurs, girls go down there and wander around in the station and find themselves a soldier and go out and sit in the park. And the park is a very large one with trees and bushes and everything else. And it’s gotten to be a kind of a bad situation.” Taft did not elaborate on what he meant by “professional” and “amateur,” but he did return often to the topic of prostitution, talking about “camp followers” who traveled to construction sites and military encampments, spreading “prostitution and promiscuity” as well as venereal disease.

At the end of this soliloquy on laundry, grocery shopping, troublesome children, pox, prostitution, and other developments caused by wartime changes in their own behavior, the female code breakers of Arlington Hall were invited t...

After Pearl Harbor brought America into the war in earnest, German Admiral Karl Dönitz saw a ripe opportunity: the vast and unprotected Atlantic coast of the United States, from Maine to Florida. The U-boat commander dispatched his submarines to cruise the East Coast, where they roamed startlingly near shore—the Germans called this the “Happy Time”—sinking freighters, tankers, trawlers, and barges. The goal was to destroy supplies being produced to feed the Allied war effort. The U.S. Navy was slow to organize an escort system for coastal shipping, and ships were sunk in full sight of horrified American citizens, who could stand on beaches and watch freighters burning.

U-boats were like terrorist cells in their ability to sow fear. They were invisible, ubiquitous, noiseless. To pluck off ships making the Atlantic crossing, the U-boats would place themselves across the convoy lanes and lie in wait. When a U-boat spotted a vessel, it would radio central command, which would alert other subs to close in. Some U-boat commanders were so daring that they would submerge and surface in the middle of the convoys, shooting at the Allies from the inside out. The Battle of the Atlantic was a war of lives and of commerce.

England needed food. The Allies needed troops and war materiel to press their campaigns in Italy and North Africa. American shipyards were churning out Liberty ships—low-cost cargo ships that were being mass-produced in unheard-of numbers—but the U-boats in 1942 were able to sink ships faster than America could make them. Making things worse was the fact that the Germans were reading the cipher the Allies used to direct their convoys, something the Americans suspected but the British were slow to admit.

U-boat messages were enciphered using Enigma machines, which the Germans believed could not be broken. To send a message, an Enigma operator inserted three rotors and positioned them in a certain order. When a single letter was typed on the keyboard, the rotors—which were facing one another, like hockey pucks stacked sideways—would turn, transforming the letter over and over. A light on the top side, an ordinary flashlight bulb, would illuminate the letter as it emerged in its enciphered form; that letter would be radioed.

The rotors were surrounded by movable outer rings, and there were plugs, called steckers, attached to a board. The upshot of all this gadgetry was that there were millions of ways a letter could travel through the encipherment process.

Before the war, a team of Polish cryptanalysts had in fact figured out the workings of the Enigma. Small, vulnerable nations surrounded by big potential enemies—Poland is bordered by Russia and Germany—tend to be hypervigilant about their neighbors, and the Polish Cipher Bureau was remarkably good. The Poles broke the Enigma during the 1930s, in part thanks to a German who passed schematics and decrypted messages to French intelligence, who passed it to them, and to a commercial model they obtained. The Polish mathematician Marian Rejewski solved the wiring, and in 1938 they built six “bomby” machines that could detect possible daily settings. In July 1939, before the Nazis overran their country, the Poles shared their discovery with the British and French. At Bletchley Park, Alan Turing and others refined the design, developing a method in which cryptanalysts could use a crib and write it beneath the cipher, then figure out, mathematically, what combination of rotor settings, wheel settings, and steckers might produce the cipher.

This “menu” permitted the machine to check for possible settings, and was in some sense an early form of a computer program.

The British built sixty “bombe” machines, which, beginning in 1941, were run by some two thousand members of the Wome...

In February 1942, however, the hypercautious German Navy added a fourth rotor to the naval U-boat Enigma machines, increasing the possible combinations by a factor of twenty-six. The Allies called this new four-rotor cipher “Shark,” and initially it proved impenetrable. The Allies lost the ability to read U-boats. The whole system went dark. This crushing turn of events occurred just months after the United States entered the war, and it began an eight-month period of death and destruction and helplessness, a time when ship after ship went down and it felt very much as though the war could swing the wrong way.

Up to that point, it’s worth noting, the Navy code-breaking office had employed some civilian women apart from Agnes Driscoll but treated them differently from men in terms of pay. According to a November 1941 proposed salary memo, female clerks, typists, and stenographers were paid $1,440 per year, while men doing the same job made $1,620. Women college graduates who had taken an elementary course in cryptanalysis made $1,800; men with those qualifications made $2,000. Women with master’s degrees made $2,000, compared to $2,600 for men. Women PhDs made $2,300; men with doctorates made $3,200. The early women came from a variety of backgrounds: Some officers’ wives and daughters liked to dabble in cryptanalysis, and there was a civilian, Eunice Willson Rice, who came from a staunchly naval family and worked on the codes of the Italian Navy.

Despite these historic inequities, the young women’s arrival could not come soon enough for the Navy. In May 1942, none other than Commander John Redman—head of the code-breaking operation, known as OP-20-G—wrote each female student, begging her to get herself to the Navy building as fast as she could. “Could you start within a week or two after the close of College?” Redman asked Ann White and Bea Norton and the other Wellesley seniors. He sent the same letter to each woman at Goucher and the other cooperating schools. “There is important work here waiting to be done,” Redman told them,

The students from the Seven Sisters and Goucher had been selected on the basis of ability, willingness, and loyalty, but tenacity was something they had to prove during the months-long correspondence course. Some had become discouraged and dropped out; others married and relocated to follow husbands; others did not answer enough problems correctly; others were rejected by the Civil Service Commission based on some aspect of their background. Back in the patriotically fervent winter of 1941, Barnard had enrolled twenty women, of whom seven stuck it out and showed up at Main Navy, the Constitution Avenue headquarters. Bryn Mawr started with twenty-seven and ended with twelve.

Code breakers, like poets and mathematicians, often do their best work when they are young. Even the great ones, like William Friedman, at some point go off the boil. In later interviews, the men described Agnes Driscoll as resorting to extreme measures to retain her authority, enforcing a rule of silence in her office, hoarding intercepts so no one could track her progress. It’s possible that Agnes Driscoll by now was past her mental prime. But it’s also possible that secreting intercepts and surrounding herself with loyal henchwomen was her way of preserving authority as the world around her was becoming bigger, more competitive, and more male. With a war on, her civilian status was more of a liability than ever. “She became fearful that she wouldn’t be able to do things,” Howard Campaigne, another newcomer, later reflected. Even the most junior officer was her superior. “As an officer, I fitted into the organization better.” This much certainly can be said: She was not as gently treated as William Friedman.

The Navy was bringing in male graduate students and college professors, reservists who provided fresh expertise and thinking. Many were mathematicians, like Driscoll, but unlike her they had enjoyed the benefit of attending institutions like Yale, Princeton, and MIT, which would never have admitted her.

It was a tense atmosphere in the downtown naval code-breaking offices, full of politics and subcurrents. There was a strong caste system: Career naval men distrusted the new, educated reservists; reservists thought they were smarter than careerists; everybody looked down on civilians. If you were a woman, you had three strikes against you.

This was the dynamic at work in the careerist Navy facility: enmities, lies, thefts, insecurities, power plays. In so many ways, the young women who joined it had no idea what they were getting into. But they were delighted to be there. The number of workers was so small—and the task so large—that the women from the Seven Sisters instantly took on real responsibility.

As the number of messages increased, the ranks of people solving them grew steadily more female. By the fourth quarter of 1943, 183 men and 473 women were working on JN-25 in Washington—more than twice as many women as men. One memo noted that it was impossible to keep the women in the dark as to what the messages said. The memo added that the most important secret was the fact that JN-25 was being worked at all, and this secret was at the “mercy of the humblest worker who ever glanced at a work book.”

The women kept that secret and became integral to the operation.

WAACs were paid less than men and did not hold the same ranks or receive the benefits. Some of this disparity would be rectified when “auxiliary” was dropped in 1943 and the WAACs became WACs, but women were by no means equal. The WAACs, coming first, bore the brunt of negative publicity, enduring gibes about their chastity and criticism of their morals and motivation for joining. Even so, they fell over themselves to enlist. 10,000 WOMEN IN U.S. RUSH TO JOIN NEW ARMY CORPS, wrote the New York Times on May 28, 1942, noting that at a single recruiting office in New York, fourteen hundred women put in requests for applications in person by the end of the first day, and another twelve hundred by mail.

“A guard’s broad shoulders held back the tidal wave of patriotic pulchritude.” The Army women were barred from serving as combatants but did fill important ancillary posts. They served as drivers, accountants, draftsmen, cooks, occupational therapists, encoders. They dispelled stereotypes. Despite fears that women would become hysterical in emergencies or that female voices were too soft to be heard, WACs worked in airplane control towers and did well.

Navy women were not an “auxiliary,” a term that overtly confers lesser status, but a naval reserve like the men’s. They were “in” the Navy, not just “with” the Navy, a key win. But there remained many inequities. Women reservists were entitled to the same pay as men, but not to retirement benefits. At the outset they could not hold top ranks. Mildred McAfee, the charismatic president of Wellesley, accepted appointment as director of the WAVES. She was a lieutenant commander at first, promoted to captain in 1943. She was often cut out of decisions, however, and deprived of the support needed to navigate a crafty and hidebound naval bureaucracy. Good-humored and beloved by the women who served under her, she joked that the attitude of her male colleagues was like that of the eighty-eighth psalm: “Thy wrath lieth hard upon me, and thou hast afflicted me with all thy waves.”

The uniform conveyed to a skeptical public that the Navy, however stubborn and reluctant to have them, cared about its women and how they were perceived. A number of code breakers admitted that the Mainbocher uniform was one reason they enlisted; some felt it was the most flattering piece of clothing they ever owned. Others chose the Navy over the Army because they preferred the classic Navy blue over the drab khaki that was the fate of the WACs. The Army women even had to wear khaki bras and girdles, which the WAVES thought was hilarious. In true competitive-service fashion, Navy women felt superior in being able to wear their own underwear.