By 1968 the USA had increased its commitment to South Vietnam in the hope of preventing the spread of communism. There were 535,000 US troops in Vietnam by that time which was more than ever. They saved South Vietnamese government but over 15,000 Americans had died in the conflict. The National Liberation Front and Vietcong launched the Tet Offensive in Feb. 1968 against the South and America. Tet, the Vietnamese New Year, was chosen to launch a surprise attack. Simultaneously, attack over 35 towns and cities. Saigon, capital city of South Vietnam and most US bases, was among the target. The aim of the offensive was to put pressure on the Americans to negotiate a settlement to leave Vietnam. The communists launched a force of over 80,000 troops against the South, but after three days of heavy losses, they were driven back. In the offensive, the US embassy in Saigon had been attacked, which indicated nowhere in Vietnam was safe.
It was to have demoralizing effect on American people who supported the war, also affected both sides Politically, Socially, and Militarily.
Politically, it affected both the USA and Vietnam. First of all, it affected the 1968 Presidential Election. Lyndon Johnson's pledge to build a Great Society in the USA had been undermined by the loss in Vietnam. Johnson announced that he would not seek re-election after the Tet offensive; some advisers argued for withdrawal and the Defense Secretary, Robert McNamara, had resigned because of his disillusionment with the war. The Democratic Party convention in Chicago where their candidate for President would be chosen descended into chaos. Outside the convention anti-war protesters were violently attacked by armed policemen. Humphrey, the Vice-President, won the Democratic candidacy, but the chaos of the events was a good for the Republican candidate Richard Nixon,