Herbert Yardley - The American Black Chamber

The American Black Chamber

MI-8 closed its doors for good on October 31, 1929, just two days after the stock market crashed. With Yardley's esoteric skills in very low demand, he took up writing about his experiences in codebreaking to support his family. His memoirs, The American Black Chamber, were published by Bobbs-Merrill in 1931. The book outlined the history of the first U.S. Signals Intelligence (SIGINT) organization, described the activities of MI-8 during World War I and the American Black Chamber in the 1920s, and illustrated the basic principles of signals security.

This work was instantly popular. Its critics at the time concluded that it was "the most sensational contribution to the secret history of the war, as well as the immediate post-war period, which has yet been written by an American. Its deliberate indiscretions exceed any to be found in the recent memoirs of European secret agents." In the U.S., 17,931 copies were sold, with 5,480 more sold in the U.K. It was translated into French, Swedish, Japanese, and Chinese. The Japanese version sold an unprecedented 33,119 copies.

This book was an embarrassment to the U.S. government and compromised some of the sources Yardley and his associates used. Through this work an estimated 19 nations were alerted that their codes were broken. Much of the post-World War I codebreaking was done by obtaining copies of enciphered telegrams sent over Western Union by foreign diplomats, as was the custom before countries had technology for specialized communications devices. William F. Friedman, considered the father of modern American signals intelligence (SIGINT) gathering, was incensed by the book and the publicity it generated in part because sources and methods were compromised and because Yardley's contribution was overstated.

While Yardley may have thought that publishing this book would force the government to re-establish a SIGINT program, it had the opposite effect. The U.S. Government considered prosecuting him, but he had not technically violated existing law regarding protection of government records. In 1933, the Espionage Act was amended, PL 37 (USC Title 18, section 952), to prohibit the disclosure of foreign code or anything sent in code. Yardley's second book, Japanese Diplomatic Codes: 1921-1922, was seized by U.S. marshals and never published. The manuscript was declassified in 1979.

The American Black Chamber represents an early example of the exposé national security books that would appear after World War II, such as The Codebreakers and The Puzzle Palace, which also focus on U.S. SIGINT operations and organizations.

In 1935, Metro-Goldwyn-Mayer released Rendezvous, a fictional film "based on a book by Herbert O. Yardley." The film, starring William Powell and Rosalind Russell, and directed by William K. Howard, concerns a German spy ring stealing U.S. government codes during World War I, as well as U.S. Army efforts to crack German codes.