Women codebreakers knew some of the biggest secrets of WWII – including plans for the D-Day invasion. But most took their stories to the grave

Before 150,000 soldiers landed in Normandy beaches for the military operation that would later be known as Day Dfew people outside the military knew what was going on.

One of the rare people who knew about the operation in advance was Jean Sims, 22, a codebreaker who noticed the use of the phrase “Overlord” in the communiqué she decoded daily. Sims was one of thousands of “Code Girls”, young women who volunteered to enlist the US Navy and worked to encode messages sent by armed forces and decode messages intercepted by enemy forces.

“She kept noticing, over and over, this term, which we all know now: Overlord. She realized it, she understood that it was something really important and she understood that these were worrying plans for a future invasion. ” said Monica Mohindra, director of the US Veterans History Project. Library of Congresswhere the Sims memories are stored.

“What she didn’t know at the time was what Overlord meant, and she also didn’t realize at the time that, other than the upper echelons, she was one of the few people in the world to know about D-Day before it happened,” he said. Mohindra.

On D-Day, more than 150,000 Allied soldiers invaded Normandy, France. The Normandy landings, which took place 80 years ago today, were the beginning of “Operation Overlord”, which would eventually see the Allies establish a foothold along the French coast. This position allowed American, British and Canadian forces to establish a second front against the German army and advance into the Nazi-occupied nation, according to the Imperial War Museum.

The Sims story was collected as part of the Veterans History Project at the Library of Congress. Mohindra said Sims’ story is just one of “thousands” of D-Day memorabilia in the projects’ archive. The archive is accessible to the public and includes unedited journals, journals, interviews, videos and audio that help readers understand the “perspective and raw emotion” of veterans who served, Mohindra said.

Decoding messages “from ships and stations around the world”

The “Code Girls” were members of the Women’s Reserve, also known as the WAVES, during World War II. According to Sims’ diary, they handled varying degrees of classified messages through the Navy Communications System. Sometimes the work involved decoding messages sent from “ships and stations all over the world,” according to Sims’ diary. Other times, they encoded messages to be sent to “addresses around the world, by radio, by mail, by courier.”

“Our goal was: to transmit the messages quickly and accurately while maintaining security: that is, to ensure that the enemy could not decrypt them and use the contents to help them sink our ships and kill our men,” Sims wrote. “The enemy knew we were there and wanted to know what we were doing. We had to keep our knowledge safe from them.”

Work also included decoding enemy messages that had been intercepted. Sims wrote in her diary that she and her fellow codebreakers worked at the Naval Communications Command Annex in Washington, DC. All communication work was done in the sixth wing of the large building. Different rooms were dedicated to decoding and encoding messages of different classification levels, and pneumatic tubes connected these rooms to what Sims called the “Main Code Room” so that messages could be easily sent back and forth.

In one notable incident, Sims and a commander managed to save a convoy at sea. Convoys may be instructed to change course because of icebergs or enemy forces in the area. A message arrived telling the convoy leader to change course immediately, but Sims noticed something strange about the call sign attached to the message and signaled a superior, who increased his concern.

“After a while, Mr. R came back and said, ‘You were right. We saved the convoy,'” Sims wrote. “There was no telling who was on board these ships or what they were carrying: perhaps food for England, or ammunition, weapons, men. It was just part of our routine and no one knew about it except Mr. R and I, and who corrected the call sign.”

Sims worked with the Code Girls before seeing messages about Operation Overlord. In Sims’ diary, mentions of Overlord are scarce and she admitted that she did not understand why the term started to appear in so many messages. The messages mentioning the operation were “short and double coded,” Sims wrote, and “obviously used code words.”

Despite being the largest air, land and naval invasion in history, the details of D-Day were kept secret from many. Surprise was essential to the plan, and Allied forces went so far as to stage false and deceptive military campaigns elsewhere in Europe to distract the German army.

Stories taken “to the grave”

Mohindra said that the work that Sims and her fellow “Code Girls” did during the war was classified, with Sims writing in her diary that she and her compatriots were warned that the consequences of breaching confidentiality included being taken to court-martialed, imprisoned or even sentenced to death. like a traitor.

Sims noted that diaries were prohibited while on duty and said she never kept one. The diary shared with the Veterans History Project was written after the Code Girls’ work was declassified, 70 years after the end of World War II. Sims died in 2017 at age 95, leaving the diary and other files he donated to the Veterans History Project as the only record of his code-breaking work.

When the Veterans History Project held a reunion of surviving Code Girls and their loved ones in March 2019 was the first time some family members understood what they had done during the war, Mohindra said. Many of their families thought the “Code Girls” had been administrative secretaries or performed other tasks necessary to the war effort, but they did not understand the full impact of their code-breaking work.

“Many of these women took their stories to the grave,” Mohindra said.