American intelligence officer, called “the father of American military intelligence.”

Van Deman followed an eclectic educational course before settling on a military career: he took a degree from Harvard, studied law for a year, and then took a medical degree (1893). He served briefly as an army surgeon and then attended the Infantry and Cavalry School at Fort Leavenworth, Kansas. In 1897 he was assigned to the Military Intelligence Division (MID). In 1901, then a captain, he organized the Philippine MID. It was in the Philippines that Van Deman developed his expertise in organizing documents and records. He was given his first covert mission, the mapping of lines of communication around Beijing in 1906. A year later he was appointed chief of the map section of the MID in Washington, D.C. General Franklin Bell, then chief of staff, who harboured a grudge against intelligence officers in general and Van Deman in particular, forced the virtual disbanding of MID by merging it with the War College.

In 1915 Van Deman returned to Washington from a second tour in the Philippines and found intelligence operations in chaos. In response he created an unofficial group of associates to collect and coordinate intelligence. With the entry of the United States into World War I in 1917, he attempted to reorganize military intelligence. The chief of staff, General Hugh Scott, found the idea of spying so distasteful that he ordered Van Deman to cease all efforts to organize a service. By adroit political maneuvering, however, Van Deman was able to gain sympathetic attention in higher government circles and soon found himself in charge of the reconstituted MID. As organized by Van Deman, military intelligence included the forerunners of the Defense Mapping Service, the Counter-Intelligence Corps (CIC), the Intelligence Command, the Industrial Security organization, the National Security Agency, and the U.S. Army Intelligence Center and School. Among those employed by him were the cryptographer Herbert O. Yardley (Yardley, Herbert Osborne); John Foster Dulles (Dulles, John Foster), later U.S. secretary of state; and Allen Dulles (Dulles, Allen W.), later director of the Central Intelligence Agency (CIA). Later in the war Van Deman served in France, and in 1919 he was the senior American intelligence officer and chief of counterintelligence for the Paris Peace Commission. He retired as a major general in 1929.

Van Deman continued his intelligence work in private life. He created a massive set of files on private citizens whose political affiliations he believed to be potentially subversive. In this enterprise he enjoyed the unofficial cooperation of local police departments, military intelligence organizations, and the Federal Bureau of Investigation (FBI). This loose network survived in many instances after regular intelligence services were severely limited in the 1930s. In 1941 Van Deman was appointed intelligence adviser to the War Department. His work during World War II earned him the Legion of Merit.

After Van Deman's death his files were taken over by a nonprofit research organization called the San Diego Research Library, which made them available not only to government agencies but also to private political groups and candidates, a practice that led to abuses. The files were routinely consulted in the granting of security clearances until 1971, when the practice was halted by executive order.