On June 10, 1917, 1st Lt. Herbert O. Yardley stood up the War Department’s first Cryptographic Bureau. Known as MI-8, this organization would establish itself as a leader in the field of military cryptology by the end of World War I.
Shortly after the U.S. entered World War I, Colonel Ralph Van Deman began building the War Department’s first intelligence organization. Functionally organized, Van Deman’s Military Intelligence Section (MIS, later a division) had both a Positive Branch focused on the collection and analysis of information about the enemy and a Negative Branch for preventing the enemy from gaining intelligence about the U.S. Army. The field of cryptology spanned both branches but found a home in the Positive Branch as, initially, the Cryptographic Bureau. By December 1917, it would become known as MI-8.
To run MI-8, Van Deman did not so much choose the 28-year-old Herbert Yardley as accept him. Just weeks earlier, the bored State Department code clerk had successfully lobbied Van Deman to organize a cryptologic service. Yardley later wrote in his autobiography, “it was immaterial to America whether I or someone else formed such a bureau. But such a bureau must begin to function, and at once.” On June 10, 1917, Yardley and two additional civilian employees got to work building the section. Yardley was commissioned as a Signal Corps first lieutenant two weeks later.
Historian Col. Bruce Bidwell noted both the critical and novel status of MI-8 when he wrote, “The eventual MI-8 Section . . . was a gradual development rather than any sudden invention. It grew up mainly on the basis of adding more elements to the original Cryptographic Bureau whenever a new technical problem arose and some recognized expert could be found to handle it.” In this erratic manner, MI-8 grew to 165 military and civilian personnel working in five subsections: Code and Cipher Solutions, Code and Cipher Compilation, Secret Inks, Shorthand, and Communications.
Code and Cipher Solutions analyzed communications from intercepted miliary radio traffic, commercial telegraph and cable companies, and seized mail, as well as atypical items like postage stamps, musical scores, religious amulets, even a pigeon’s wings. The amount of work was overwhelming, especially after the U.S. Navy stopped its own cryptanalysis efforts, letting the Army take the lead. During the war, the subsection read more than 10,000 messages and solved fifty codes and ciphers used by eight foreign nations.
While the Solutions group was breaking foreign codes, the Code and Cipher Compilation Subsection was tasked to “drop everything and revise the entire system of War Department codes and ciphers,” which had previously been compromised. It developed new secure communication methods for American military attachés and intelligence officers in the U.S. Army overseas.
The Secret Ink Subsection developed reagents for all types of invisible inks. At its peak, it was reviewing more than 2,000 items weekly and even uncovered communications directing sabotage against American defense industries. The Shorthand Subsection employed experts to analyze and catalog more than fifty shorthand systems that could possibly be used as codes. Finally, the Communications Subsection operated round-the-clock, averaging the secure transmission of more than 100 sensitive and classified messages per day.
By August 1918, on the verge of a nervous breakdown from overwork, Yardley received orders to sail for Europe to liaise with allied cryptographic organizations. He left MI-8 in the capable hands of his assistant, Capt. John M. Manley, for the duration of the war. By the time Yardley returned from France in 1919, however, budget and personnel cuts had caused the section to be disestablished; some subsections were abolished, others transferred to different organizations. Only the Solutions group was somewhat intact, and Yardley would move it to New York City where it would operate as the joint State–War Department “American Black Chamber” for the next ten years.
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Article by Lori S. Stewart, USAICoE Command Historian. New issues of This Week in MI History are published each week. To report story errors, ask questions, request previous articles, or be added to our distribution list, please contact: TR-ICoE-Command-Historian@army.mil.