Lieutenant Colonel A. Peter Dewey was a U.S. Army officer who became the first American military casualty in the Vietnam War. He was born in 1923 and served in World War II before joining the newly established U.S. Army Special Forces during the post-war years. In 1945, following the end of World War II, Dewey was sent to Vietnam, which was then part of French Indochina, as part of a mission to assist the French in their fight against the Viet Minh, who were fighting for independence. A member of the Office of Strategic Services (OSS), the precursor to today’s CIA, Peter Dewey arrived in Vietnam just two days after Japan’s surrender on September 2, 1945. His mission was to help search for missing in action personnel and to assist the British general, newly arrived in Saigon, in maintaining order in the southern half of Vietnam.

On September 26, 1945, Lieutenant Dewey was killed in a confrontation with Viet Minh forces near Saigon, just a few months after the end of World War II. His death occurred during a time of rising tensions between the French colonial forces and the Viet Minh, and though his death was a result of a firefight, it marked the first American military fatality in Vietnam, long before the escalation of U.S. involvement in the conflict in the early 1960s.

Dewey's death is often considered a symbolic start to American involvement in Vietnam, though the U.S. had not yet officially committed to the war at that point.