Chapter 26 (The Vietnam War) By haybug101 May 17, 1955 U.S. military sent to South Vietnam May 17, 1964 Congress passes Gulf of Tonkin Resolution May 17, 1965 U.S. combat troops arrive in Vietnam May 17, 1968 Tet Offensive begins May 17, 1968 Anti-war protest in Chicago May 17, 1970 National Guard troops kill student protesters at Kent State May 17, 1973 Last U.S. troops leave Vietnam