Military Intelligence --this week in history. Nov 1921

By U.S. ArmyNovember 8, 2012

The delegates at the Washington Naval Conference, November 1921
(Photo Credit: U.S. Army) VIEW ORIGINAL

Concerned about large-scale ship-building programs in the US, Great Britain,

and Japan following World War I, US President Warren G. Harding organized

the Washington Naval Conference in late 1921. The conference was held in

Washington DC and nine nations attended. Harding's goal was to establish

limits on the number and tonnage of warships of each nation. In addition to

concerns of a naval arms race, Harding and other nations were concerned

about Japanese expansion in the Pacific.

Herbert Yardley's "Black Chamber," a civilian cryptography bureau funded

jointly by the State Department and the US Army, intercepted and deciphered

the communications of the participating countries' delegates. Over the

course of a few months, Yardley's team deciphered or translated nearly 5,000

messages. Notably, shortly before the conference, Yardley's team had a

major success when it broke the Japanese diplomatic code and learned of the

Japanese government's instructions to its ambassadors. Naturally, knowing

the lowest naval ratio the Japanese were willing to accept put the US in a

powerful negotiating position.

The Washington Naval Conference is hailed as the first disarmament

conference in history and a successful one as well. The resulting treaties

remained in effect until 1936 when Japan backed out. The role of the Black

Chamber during the conference also had a significant impact on the field of

signals intelligence. The Black Chamber enjoyed increased funding and

support in the years following, and its chief, Herbert Yardley, received the

Distinguished Service Medal. This support lasted until the Black Chamber

was closed by Secretary of State Henry Stimson, in 1929.

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"This Week in History" is a feature on the Command History Office website.