Herbert Yardley

From Academic Kids

Herbert O. Yardley

Herbert Osborne Yardley (13 April 1889-7 August, 1958) was an American cryptologist most known for his book The American Black Chamber (1931). The title of the book refers to the cryptographic organisation of which Yardley was the founder and head — MI8; under Yardley, the cryptanalysts of the American Black Chamber broke Japanese diplomatic codes and were able to furnish American negotiators with significant information during the Washington Naval Conference of 1921-1922. He later helped the Nationalists in China break Japanese codes and worked briefly for the Canadian government, helping it set up a cryptological section.


Early life

Yardley was born in 1889 in Worthington, Indiana. His mother, Mary Emma Yardley, died when he was 13. His father, Robert Kirkbride Yardley, was a station master and telegrapher for a railroad. From him, Herbert learned to use the telegraph.

After graduating high school in 1907, Yardley worked as a telegrapher for a railroad. He spent his free time learning how to play poker, and applied his winnings towards his further schooling. In 1912, after passing the civil service exam, he was hired as a government telegrapher.

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 World War II. He also worked in the American Black Chamber.


His work in the code room started his career in cryptology by breaking the U.S. government codes that crossed his desk. At that time, American codes were very weak and Yardley solved them easily. He was shocked to learn that President Wilson was using a code that had been in use for over ten years. The weakness of American codes worried Yardley, especially considering the war in Europe, so he wrote up a hundred-page “Solution of American Diplomatic Codes” and gave it to his boss.

Breaking American codes got Yardley wondering about the codes of other countries. American participation in the war gave Yardley an opportunity to sell the government on his idea to set up a section to break other countries' codes. He convinced Major Ralph Van Deman of the need and in June-July of 1917 Herbert Yardley became a first lieutenant in the Signal Corps and head of the newly created eighth section of military intelligence – MI-8.

Yardley proved to be a very good administrator and during the war the people of MI-8 performed well even if they did not have any spectacular successes. After the war, the American Army and the State department decided to jointly fund MI-8 and Yardley continued as head of the “Cipher Bureau”. They set up shop in New York City for legal reasons.

Cracking Japanese codes was a priority. Kahn (2004, pg 62), states:

The most important target was Japan. Its belligerence toward China jeopardized America's Open Door policy. Its emigrants exacerbated American racism. Its naval growth menaced American power in the western Pacific. Its commercial expansion threatened American dominance of Far Eastern markets.

After close to a year, Yardley and his staff finally managed to break the Japanese codes and were still reading Japanese diplomatic traffic when Washington hosted the Washington Naval Conference in 1921. The information the Cipher Bureau provided the American delegation was instrumental in getting the Japanese side to agree to a 5:3 ratio instead of the 10:7 ratio the Japanese wanted. This was the height of Yardley's cryptanalytic career.

Unfortunately, Yardley spent much of his time in New York involved in unrelated activities. Also, the flow of diplomatic telegrams dried up as companies became less willing to break the law to help the government. In Washington, William Friedman was actively exploring cryptographic frontiers for the Army – the Cipher Bureau was becoming irrelevant. However, it was moral indignation that finally doomed the bureau. Henry L. Stimson was Secretary of State under President Hoover. When he found out about Yardley and the Cipher Bureau, he was furious and withdrew funding, summing up his argument with “Gentlemen do not read each other's mail.”

Yardley is a member of the Military Intelligence Hall of Fame.

After the Black Chamber

MI-8 closed its doors for good on 31 October 1929 – just two days after the stock market crashed and the Great Depression began. Not a good time for someone with Herbert O. Yardley's rather esoteric skills to be out of a job. Unable to find anything promising and with a wife and young son to support, Yardley decided to try writing about his old job. His memoirs, The American Black Chamber, was published by Bobbs-Merrill in 1931.

The American Black Chamber was entertaining and based on fact – mostly telling the story of Yardley's breaking of the Japanese codes and the effect of that at the Washington Naval Conference. It sold well and gave Yardley a taste of fame and infamy. The American government was highly unhappy. The Japanese government was embarrassed and highly unhappy. 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 (although pressure from the US on the Candian government meant this was limited) and China during World War II, but he was never again given a position of trust in the U.S. government. Despite this in 1999 he was given a place in the NSA Hall of Honour.

None of Yardley's many later attempts at writing were as successful as The American Black Chamber. Still, he published several articles, three mystery novels, and worked on a few movies (including Rendezvous, based very loosely on one of his novels, The Blonde Countess) as a writer and technical advisor. It paid the bills.

Yardley died at 1:15 pm on 7 August 1958, a week or so after having a major stroke. He is buried at Arlington National Cemetery, Grave 429-1 of Section 30.


  • David Kahn, The Reader of Gentlemen's Mail: Herbert O. Yardley and the Birth of American Codebreaking, Yale University Press, 2004. ISBN 0300098464



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