American Black Chamber closed
May 1929
After World War I, Herbert Yardley and General Marlborough Churchill argued for the retention of MI-8, the code and cipher section of the Military Intelligence Division, as a permanent peacetime cryptologic department. They were successful, and in 1919, the Cipher Bureau was formed. It was a branch of the MID jointly funded by the War and State Departments.
The Bureau was informally known as “The American Black Chamber,†a name coined by Yardley in reference to the code-breaking Black Chambers of Europe. The very existence of the Black Chamber was a secret, and it operated under the cover of a private business, the “Code Compilation Company,†in New York City.
Yardley and his chamber had several notable successes, most importantly the breaking of Japan’s diplomatic codes. This gave the United States a considerable negotiating advantage during the 1921 Washington Peace Conference, resulting in a favorable treaty. During the 1920s the Bureau intercepted and read more than 45,000 telegrams in the codes of more than twenty foreign governments. However, with the advent of the administration of President Herbert Hoover in 1929, Secretary of State Henry Stimson withdrew State Department funding from the bureau because, as he explained many years later, “Gentlemen do not read each other’s mail.†Consequently, the Bureau went out of existence shortly thereafter, in May 1929.
Abruptly unemployed and in financial straits, Yardley sought relief through writing a revealing memoir, “The American Black Chamber,†which soon became a best-seller. The embarrassed U.S. government, although rejecting Yardley’s position that because the bureau had been dissolved there was no longer any reason to protect its secrets, did not prosecute Yardley or his publisher, but instead denied that the bureau had ever existed. Shortly after the closure of the Black Chamber, all cryptologic functions were transferred to the Signal Corps, and a new organization emerged. It was called the Signals Intelligence Service, chaired by William Friedman, who had been at the head of the Signal Corps’ Code and Cipher Section since 1921.
“This Week in History†is a feature on the Command History Office website. Those with AKO access you can view it at https://ikn.army.mil/apps/mi_history/.
To learn more about the 2012 MI Branch and Corps Commemoration, see the public website, https://www.ikn.army.mil/apps/mi_comm/.
