On September 26, 1945, Lt. Col. A. Peter Dewey became the first American soldier to die in Vietnam. Apparently mistaken for a Frenchman, Dewey was gunned down by Vietminh troops while driving a jeep to the airport. The son of a former Illinois congressman, he had been the head of the American O.S.S. mission. However, because the conflict had not yet fully developed at this time, some sources consider the first U.S. casualties of the Vietnam War to be Major Dale R. Buis and Master Sergeant Chester M. Ovnand who were killed in 1959 during a guerilla attack at Bienhoa.