Joseph Rochefort

Captain Joseph John Rochefort (1898-1976) was an Amercian cryptanalyst.

Captain Rochefort was a major figure in the U.S. Navy's cryptologic and intelligence developments from 1925 to 1947. He headed the navy's fledgling cryptanalytic organization in the 1920s and provided singularly superb cryptologic support to the U.S. fleet during World War II, leading to victory in the war in the Pacific. At the end of his career (1942-1946), Rochefort successfully headed the Pacific Strategic Intelligence Group in Washington.

Rochefort was born in 1898 and enlisted in the navy in 1918. He was commissioned an ensign after graduation from the Stevens Institute of Technology. Rochefort's tours ashore included cryptanalytic training under both Captain Laurance Safford and Agnes Meyer Driscoll in 1925; a stint as second chief of the Department of Naval Communications' newly created cryptanalytic organization, OP-20-G, from 1926 to 1929; training in the Japanese language from 1929 to 1932; and a two-year intelligence assignment in the Eleventh Naval District, San Diego, from 1936 to 1938. Until 1941, Rochefort spent nine years in cryptologic or intelligence-related assignments and fourteen years at sea with the U.S. fleet in positions of increasing responsibility.

In early 1941 Laurance Safford, again chief of OP-20-G in Washington, sent Rochefort to Hawaii to become OIC of Station Hypo in Pearl Harbor. The reasons for Rochefort's appointment were obvious: he was an expert Japanese linguist, an experienced and very talented intelligence analyst, and a trained cryptanalyst.

Rochefort handpicked many of Hypo's augmentees, and it contained the navy's best cryptanalysts, traffic analysts, and linguists, including Thomas Dyer, Wesley A. (Ham) Wright, Joseph Finnegan, General Alva Lasswell, Thomas Huckins, and Jack Williams.

After the Japanese attack on Pearl Harbor, Rochefort and the station Hypo experts eventually were able to read enough of Japanese naval communications to provide daily intelligence reports and assessments regarding Japanese force disposition and intentions. During the peak month of May 1942, Rochefort reviewed, analyzed, and reported on as many as 140 decrypted messages per day. These reports went directly to the highest-ranking fleet commanders.

The most significant cryptologic success was the timely and accurate support provided by Rochefort and his unit surrounding the Battle of Midway, considered by many to be the turning point of the war in the Pacific. Station Hypo provided accurate and timely intelligence reports for the rest of the Pacific War; these reports were used by the most senior navy officers for strategic and tactical decisions.

Rochefort died in 1976. In 1986, he posthumously received the President's National Defense Service Medal, the highest military award during peacetime, for his support to the Battle of Midway.