U.S. #5738a
2022 60¢ Women Cryptologists of World War II (Imperforate)
Issue Date: October 18, 2022
First Day City: Annapolis Junction, MD
Type of Stamp: Commemorative
Printed by: Ashton Potter (USA) Ltd.
Printing Method: Offset
Format: Pane of 20
Self-Adhesive
Quantity Printed: 18,000,000
During World War II, both the Allied and Axis powers used radio messages to communicate. However, because they were easily intercepted, cryptography was widely used to mask the contents of a message through complicated code. Naturally, both sides tasked large teams with cracking these codes in order to obtain secret information. Women across America took up non-combat jobs while men were away fighting. This included serving as code breakers.
One of the most infamous codes was generated by Japan and their Type B Cipher Machine, codenamed "Purple" by the United States. Members of the US Army Signals Intelligence Service (SIS) were assigned the monumental task of breaking it. This included thousands of women, of whom Genevieve Grotjan became a central figure. After 18 months with no headway, the SIS team was at a loss for what to try next. Finally, in September 1940, Grotjan made a discovery that turned the tide in our favor. She found trends in Japan's coded messages that no one else had detected.
With Grotjan's groundwork, other cryptologists were able to make additional breakthroughs. The US was finally able to decode Purple and read Japanese diplomatic messages, giving the Allies a major tactical advantage. Without the women cryptologists of SIS, World War II victory may never have been possible.