Kelly McSweeney

May 20th 2020

WW2 Codebreakers Secretly Hacked Military Messages


The United States had a secret weapon in World War 2: young women who hacked military messages. Now, these WW2 codebreakers are getting the credit they deserve.

While men were fighting overseas, a different kind of battle was being fought by American women in WW2. A group of approximately 10,000 women were secretly recruited and worked behind the scenes, breaking into German and Japanese communications systems. They decoded messages that had been encrypted on multiple levels, which was extremely complicated and crucial to military operations.

In contrast to those who returned from the war with stories of battlefield glory, codebreakers couldn’t talk about what they were doing, so they didn’t become war heroes. In the years since, these women’s stories have begun to come out, thanks to efforts like “Code Girls” by Liza Mundy.

The Stigma of Women in WW2

In the World War 2 era, there was a stigma associated with codebreaking because it was considered secretarial. The prevailing stereotype was that women were better at “boring” tasks like crunching numbers, such as the “Hidden Figures” who computed rocket trajectories.

Though codebreaking should have been a prestigious job, the women could be prosecuted for treason if they revealed what they were doing. Instead, people assumed the women were assisting the military men. If anyone asked, the codebreakers were told to say they emptied trash cans and sharpened pencils.

Who Were the Codebreakers?

During the war, Axis powers shared information in messages that were coded on multiple levels, which made them extremely difficult to break. It took a special mixture of patience, creativity and logic to break the codes and read the messages. School teachers and recent college graduates were the perfect candidates. Professors, college presidents and military officers recruited women from the Seven Sisters colleges in the Northeast and schoolteachers from the South.

The women were tapped for the role because they were skilled in both math and language, andthey also had to answer a couple of questions. According to CNN, if the women liked crosswords and weren’t engaged, they were considered suitable for the job. During this time period, it was assumed that married women would leave the workforce; in reality, married women such as Beatrice Schilling and Hedy Lamar were inventing new military technologies.

At the height of the codebreaking program, there were approximately 4,000 women at a U.S. Navy code-breaking facility at what is now the Department of Homeland Security in Washington, D.C., and 7,000 women at Arlington Hall in Arlington, VA.

Codebreakers and Cryptology

These young women pioneered data encrypting and invented early cybersecurity techniques that are still used today. According to Smithsonian, the women had to work through endless code and cipher systems, which were often layered for maximum confusion.

They would spend days staring at strings of letters, trying to make sense of the scrambled messages. They might, for example, be looking at a Japanese message that was spelled out in Roman letters and then mixed up.

The work was tedious, and there was no rulebook, so the women learned as they went. They used certain tricks to find patterns in the nonsensical messages, such as finding frequently used letters or looking for the coded version of “begin message here,” which would give the codebreaker a place to start. These techniques helped form the basis for modern military communication, data security and encryption.

They Helped End The War

WW2 codebreakers were an integral part of military operations, although they didn’t get credit for it. In fact, the first American to learn that WW2 was over was a female codebreaker who was head of a U.S. Army language unit. Smithsonian reports that Virginia D. Aderholt deciphered and translated the message from Japan to Switzerland (who remained neutral during the war) declaring their unconditional surrender in 1945. She decoded the message, which was then rushed to President Harry S. Truman, effectively ending the war.

Aderholt was one of many exceptional women who eavesdropped on Japan and Germany to get ahead. They provided intelligence that helped Allied forces sink enemy supply ships and gun down the plane of Isoroku Yamato, “the architect of Pearl Harbor,” according to Smithsonian. Female codebreakers figured out precisely where the Japanese army was located and where they were likely to be moving; discovered the origins and destinations of radio signals; and tracked the location and movement of troops.

Mundy told CNN that without the WW2 codebreakers, the attack on Pearl Harbor could have been even worse. Agnes Driscoll, for example, was working on Japanese fleet code for more than a decade. She diagnosed how their system worked, figured out how to read Japanese naval communications and shared her knowledge with the male naval officers who went to the Pacific (and got the credit).

The WW2 codebreakers were almost too good at their jobs. Toward the end of the war, they were supplying more information on Japanese supply ships that the military could keep up with, according to Smithsonian. Even after the war ended, the women kept the secret about what they were really doing to help with the war effort. Many of them went home, while others stayed in the intelligence community and ended up in high-ranking positions — some even outranking their military husbands.