A Canadian opens up about her secret wartime work — eavesdropping on Japan

At age 97, Marjorie Stetson has never told anyone her secret code number — until now.

That's the identity code — 225 — that she typed on every page of her highly classified work for the Canadian Armed Forces during the Second World War.

The retired sergeant's wartime work was so covert, she said, she had to sign 15 separate copies of Canada's Official Secrets Act.

"Nobody knew where I worked," Stetson told CBC News from her home in Massachusetts ahead of Remembrance Day. "Nobody knew what we did. Even my parents never knew what I did in the service."

Her husband, an American sailor she met at a celebration marking the end of the war, passed away a decade ago. She never told him what she really did during the war.

Today, Stetson herself is only now learning about the true scope of her role and the significance of all those sheets of white paper she filled with encrypted messages from Japan.

WATCH | Retired Canadian sergeant reveals her secret work from WW II:

"She was on the front line of the radio war," said military historian David O'Keefe, who studies Second World War code breaking and signals intelligence. "She really was at the forefront of a dawning of a new era."

Stetson's work made her part of a large transatlantic intelligence network that played a direct role in the United States' decision to drop atomic bombs on the Japanese cities of Hiroshima and Nagasaki, said O'Keefe, a professor at Marianopolis College in Quebec.

Stetson used a radio receiver to intercept Japanese army and air force communications. She used a special typewriter to transcribe the Japanese codes she heard. Those number-filled documents were sent to code breakers in the U.S. and sometimes England, said O'Keefe — giving the Allies an intelligence edge in the Pacific region

"What she was involved in was extremely important for the war effort," he said. "All that information she gets is eventually turned into actionable intelligence, which then translates into better decision-making and perhaps the saving of thousands, if not millions, of lives."

Stetson is the only woman out of the dozen she worked with who is still alive to tell her story.

This year marks the 80th anniversary of the establishment of the Canadian Women's Army Corps (CWAC). Faced with a shortage of manpower in 1941, the military created the CWAC and enlisted thousands of women to serve. It's a milestone that paved the way for women to serve in the regular forces.

Stetson was just 18 years old when she joined CWAC in 1942.