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Cipher heroes

Stamp honors WWII’s female codebreakers

The Women Cryptologists of World War II stamp shows code characters superimposed on a military recruitment poster.

The Postal Service is releasing its latest Forever stamp, Women Cryptologists of World War II, on Oct. 18.

The stamp’s mysterious image shows code characters superimposed on a recruitment poster for WAVES, or Women Accepted for Volunteer Service, part of the U.S. Naval Reserve. The code displayed on the stamp was a cipher used by the Japanese in World War II to encrypt diplomatic messages.

Genevieve Grotjan discovered the key to cracking that code, called “Purple,” in 1940. This allowed the United States to intercept information sent in Japanese diplomatic messages until the end of the war.

She was one of thousands of women, civilian and military, who filled roles that normally would have gone to male soldiers who were needed to fight overseas. By war’s end, 7,000 of the staff of 10,500 in the U.S. Army Signal Intelligence Service were women.

Sworn to secrecy under threat of treason, the clandestine army worked tirelessly on work that could be, by turns, boring and exhilarating.

Because of the hush-hush nature of their efforts, their contributions have largely gone unheralded. This stamp brings their contributions, however blurred to subsequent generations, to light.

Women Cryptologists of World War II is available in panes of 20 at Post Offices and at