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

Ambon. Canton. Davao. Haiphong. Hankow. Kiska. Kobe. Kuching. Kupang. Osaka. Palembang. Rabaul. Saigon. Takao. Wewak. Dot Braden until a few months earlier had never heard of most of these places. Now they ruled her life. They kept her running from the big table where she worked, over to the overlapper’s console, then back again to her spot at the big table. These were the names of places, somewhere in Asia or the South Pacific, likely to be mentioned toward the beginning of messages coded in 2468, the main Japanese water-transport code, or one of the other, smaller transport codes.

Or rather, they were some of the places. Transport code 2468 was massive; 2468 was everywhere; 2468 dominated the Pacific Ocean. Anything anybody needed was sent by water. Water was how the rice was transported, and the soldiers, and the spare airplane parts. To move the goods the Japanese Army needed, the marus were always sailing. Always leaving and arriving. A maru could be a tanker, a freighter, a cargo ship, a barge, a cable layer, a motor transport. They plied between Hiroshima, Yokohama, Wewak, Saipan, Tokyo, Manila, the Truk Lagoon. Exotic places. It was not necessary for Dot to know how to pronounce the cities and ports, but it was helpful to know the four-digit code groups that stood for them. Code system 2468 commanded Dot’s attention, controlled Dot’s movements. It filled her brain.

A job more unlike teaching Virginia schoolchildren would be hard to imagine. No longer was Dot Braden standing at a chalkboard, explaining physics formulas to eye-rolling teenagers, or ordering senior girls to march and salute. Instead, she was sitting head down at a table puzzling over words she had never heard before she came to Arlington Hall. “Sono.” “Indicator.” “Discriminant.” “GAT.” The sono was the number appended to messages that had been divided into parts before being transmitted. Sono #1 was the first part, Sono #2 was the second part, and so on. The discriminant was the number that identified the system—for instance, 2468. The indicator was the tiny clue that told you what book to look in. GAT stood for “group as transmitted”: the code group plus the cipher. The GATs were what you saw when you looked at the message for the first time.

Dot, of course, was not to utter any of these words outside the high wire double fences of the Arlington Hall compound. People were warned never to use, outside the building, the words they used inside it. “This material is extremely secret and must be treated with the utmost care,” one training document said. “Some of the words which you will consider elementary have been used only in this code, eg KAIBOTSU SU ‘to sink a ship’. If you should mention this word to any one connected with the Axis or in some way succeed in letting it get into improper hands, this one fact alone would betray to the Japanese that we are reading their most recent transport code.”

Dot did not know anyone “connected with the Axis.” Even so, she never mentioned anything to anybody. On the bus, she kept mum. She and Crow still never discussed their work, even though they lived together, ate together, and shared a bed. When she wrote letters to her brothers, or to Jim Bruce or George Rush, she did not tell them what she did. She talked about eating red beans and rice and frozen peaches and going to the beach on the bus and the streetcar. Just the silly things she and Crow did in their time off. She liked the work at Arlington Hall and, unlike some of her colleagues, had few complaints, apart from the fact that northerners thought southerners were backward and stupid.

At Arlington Hall, Dot worked at a wooden table with other women, all of them sitting together in a big room in Building B. She was given cards with series of four-digit GATs, and it was her job to run the GATs against a bank of code groups she had memorized. The messages she got were the urgent ones. Routine 2468 messages were sent to the punch-card room, to be processed by machines. It was a tenet at Arlington Hall that every message had to be processed, no matter how insignificant or routine. No message was devoid of intelligence use.

The ones that must be decoded quickly—the ones that might require action—had to be deciphered by hand, and these were the messages Dot got. She would scan each one and compare the groups on the page to the code groups she kept stored in her head. She would look for a group whose position suggested that it likely meant “maru,” or—this was always exciting—“embarking” or “debarking.” Dot sat near a pole, and when she saw a code group that seemed important, she would jump up and almost hit her head on the pole as she ran to take the message to the overlappers’ unit, a group of women who worked in another room. They would take her message and place it on a big piece of paper with other messages encoded using the same additives.

Often, a young woman named Miriam was the overlapper waiting to receive Dot’s breathlessly delivered handoff. Miriam came from New York City, and she was one of the most condescending northerners Dot had ever known, and that was saying something. One day, over lunch in the cafeteria, Miriam said, “I have never yet met a southerner who can speak proper English.” This offended Dot, as it was intended to do. “Another smart aleck New Yorker,” she thought, but she did not say it. She comforted herself by assessing the so-called yellow diamond on Miriam’s ring finger—Miriam had a fiancé, or claimed to have one—and reflecting that both the diamond and the fiancé were likely fakes.

Despite their low opinions of each other, Dot and Miriam had to work seamlessly together, and they did. Dot would get the messages started by identifying some of the code groups, and Miriam would place the message Dot brought her. From the overlapping station, the work sheet went to a reader, who would decipher the meaning. Information from the finished translations would make its way to the staff of General MacArthur or to a submarine captain who would do what needed to be done.

The language of the 2468 messages was telegraphic in style. Short, straightforward, and no-nonsense, the messages consisted of sailing schedules, harbormaster reports, reports on the water levels of ports and transportation of cargo. Sailing schedules were the simplest. These included the transport number, the date, the time the maru would be arriving or leaving, and its destination. Others concerned the movement of troops or equipment. A few dealt with transportation of the wounded or ashes of the dead. The marus out there in the Pacific Ocean carried everything: food, oil, supplies, human remains.

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