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

Asking around, Wilma Berryman found out that the U.S. Navy had developed a correspondence course, to train its own officers but also to permit hobbyists and other potential civilian applicants to homeschool themselves in breaking codes. The purpose was not so much to teach the subject as to locate talent and winnow out those who had none. Wilma Berryman spent several years tackling the course, sending away for lessons, completing the exercises on her own time, and sending them back. The two code-breaking operations were porous enough that her answers found their way to William Friedman, who was always scrutinizing civil service rolls and whatever other sources he could gain access to, evaluating test scores and looking for the right abilities. Upon being hired, Wilma Berryman was put on the Italian desk—which is to say, she was given a beginner’s textbook on the Italian language and plunged willy-nilly into the secret communications of the fascist government of Italy. Every morning, one of Berryman’s colleagues liked to come over to her table and ask her, “How’s Benito doing this morning?”

That was how the Friedman operation worked: It was a teach-yourself kind of place. Newcomers would spend the morning studying training manuals, puzzling out the answers to questions like “What four things were thought by Captain Hitt to be essential to cryptanalytic success?” (perseverance, careful methods of analysis, intuition, and luck) and “What two places in every message lend themselves more readily to successful attack by the assumption of words than do any other places?” (the beginning and the end). They spent afternoons attacking actual codes.

Wilma Berryman loved it.

So did Delia Ann Taylor, a tall, brainy midwesterner who graduated from Sweet Briar College in Virginia and had a master’s degree from Smith College. Working near her was Mary Louise Prather, the daughter of a genteel family that had fallen on hard times. It was Prather’s job to work the office machines—sorter, reproducer, tabulator, keypunch—that Friedman, a master of winkling things out of a closefisted government bureaucracy, had persuaded his bosses to buy him. While Prather’s might seem like a menial job—running office machines was considered women’s work—these were not conventional machines but had been modified to assist with sorting enemy messages.

Prather also filed the intercepts, which themselves were a kind of contraband. Since the United States was not, strictly speaking, at war, collecting radio and cable transmissions of foreign diplomats was not, strictly speaking, legal. The Communications Act of 1934 imposed “severe penalties for interception of diplomatic traffic,” as one memo noted, but the code breakers had decided to overlook that. Friedman’s Army superior, the now major general Joseph Mauborgne, felt the law could be ignored. Even so, intercepts were hard to come by: The Army did not yet have many clandestine radio intercept stations of its own, so they got some messages from the Navy and some from friendly cable companies who handed them over under the table. Prather kept a careful log of every last one.

And there was twenty-seven-year-old Genevieve Marie Grotjan, hired as a “junior cryptanalyst” in October 1939 for a salary of $2,000 per year. It was Grotjan who was standing waiting for the men in the Munitions Building to notice her. A native of Buffalo, New York, Grotjan had been a brilliant all-around student at Buffalo’s Bennett High School, where she delivered the salutatorian’s address in the customary Latin. She received a Regents scholarship to attend the University of Buffalo, where she majored in math and belonged to the International Relations Club. Graduating summa cum laude in 1938, she won a math prize, received a teaching assistantship to do graduate work, and aspired to teach college math. Like so many women of her day, however, Grotjan was unable to find a university math department willing to hire her. So she came to Washington and was hired as a statistical clerk at an obscure agency called the Railroad Retirement Board, where it was her happy task—she enjoyed it—to calculate pensions. When she took a math exam to secure a routine pay raise, her score attracted Friedman’s attention. She received a call from the Signal Intelligence Service and was asked if she would like a job in the “code section.” Grotjan didn’t know what any of that meant, but she said yes.

Many of the code breakers were social with one another, but Grotjan was not one of these. Shy and introverted, she favored rimless eyeglasses, high-collared blouses, and a pragmatic hairstyle that consisted of tight blond pin curls crimped in a halo around her forehead. She rented a room in a boardinghouse at 1439 Euclid Street, a modest section of northwest Washington.

After less than a year on the job, however, Grotjan was shaping up to be one of the team’s most promising code breakers. She was known for her thoroughness, powers of observation, and attention to detail. Humble and reticent, she possessed the pure soul of one who lives for numbers, oblivious to office politics and rivalries, which did exist. Based on the aptitude she demonstrated, she was assigned to the most pressing problem Friedman’s office had undertaken: the cipher system used by Japanese diplomats around the world. It was a completely different system from that of their military counterparts: While the Imperial Japanese Navy often used laborious pen-and-paper systems, which involved a lot of adding and figuring, Japanese diplomats favored the newer machine-generated ciphers. The small team that Grotjan belonged to was trying to do something that almost certainly had never been done: reconstruct an unknown machine without having seen it or even a piece of it—not so much as a blueprint or drawing. They were attempting to penetrate the machine’s inner workings by scrutinizing its pilfered output, sitting at tables looking at strings of random-seeming letters.

There were many challenges to this task, chief among them that the Japanese machine had been produced in an environment to which they did not have access. This was an era when governments and businesses alike were turning to cipher machines to keep their messages secure from intermediary parties (anybody from a Morse operator to an actual spy) and inventors were always designing new machines to enable them to do that. Friedman’s office kept its own “nut file,” recording the outlandish systems that hobbyists tried to sell them. Usually, the inventor wanted either a job or a million dollars and threatened to sell to the Russians or Germany if the U.S. government didn’t bite. Friedman, like his Navy rival Agnes Driscoll, was a master at finding the weaknesses of these machines, and his acolytes often could break a nut’s systems in a matter of hours.

But some machines on the Western market were first-rate. One of the best was called Enigma. Envisioned as a tool for bankers, the Enigma, invented by a German engineer and marketed by a German company in the 1920s, had been adapted for military use by the Nazis. In 1933, Hitler ordered it taken off the commercial market, however, so his military could have sole access. Many military machines, like Enigma, were small and light and sturdy, not much bigger than typewriters. Enigma in particular was a durable, portable, battery-powered device that could be lugged around and used during battle, or welded to the command center of a submarine, where it had one job and one job only: to change each letter of a message to a different letter.

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