Inside a reconstructed bunker at Khe Sanh, Vietnam. In 1968, roughly 6,000 U.S. Marines were besieged for nearly six months at the isolated base in Quang Tri province, near the former Demilitarized Zone. The siege has been widely viewed as a diversion for the Tet Offensive, in which communist troops simultaneously attacked dozens of South Vietnamese cities and towns, leading to a month of intense fighting, an event which turned the tide of American public opinion against the war. April 24, 2013.