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Born in 1889 in Indiana, Herbert O. Yardley began his career as a code clerk in the State Department. He accepted a Signal Corps Reserve commission and served as a cryptologic officer with the American Expeditionary Forces in France during WWI. In the 1920s he was chief of MI-8, the first U.S. peacetime cryptanalytic organization, jointly funded by the U.S. Army and the Department of State. In that capacity, he and a team of cryptanalysts exploited nearly two dozen foreign diplomatic cipher systems. MI-8 was disbanded in 1929 when the State Department withdrew its share of the funding.

Out of work, Yardley caused a sensation in 1931 with the publication of his memoirs of MI-8, "The American Black Chamber." In this book, Yardley revealed the extent of U.S. cryptanalytic work in the 1920s. Surprisingly, the wording of the espionage laws at that time did not permit prosecution of Yardley. (This situation was changed two years later with a new law imposing stiff penalties for unauthorized revelations of cryptologic secrets.)

Yardley did some cryptologic work for Canada and China during World War II, but he was never again given a position of trust in the U.S. government.

On August 7, 1958, Herbert O. Yardley, one of the pioneers of modern American cryptology passed away.

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• To learn more about the Yardley/Black Chamber Exhibit and other National Cryptologic Museum exhibits, take our Virtual Tour.