Before the Vietnam War, most Americans would have been hard pressed to locate Vietnam on a map. South Vietnamese president Diem's regime was extremely unpopular, and war broke out between Communist North Vietnam and South Vietnam at the end of the 1950s. Kennedy's administration tried to prop up the South Vietnamese with training and assistance, but the South Vietnamese military was feeble. A month before his death, Kennedy signed a presidential directive withdrawing 1,000 American personnel, and shortly after Kennedy's assassination new president Lyndon B. Johnson reversed course, instead opting to expand American assistance to South Vietnam.

Over the next few years, the American military commitment to South Vietnam grew dramatically, and the war effort became both deeper and more complex. The strategy included parallel efforts to strengthen the economic and political foundations of the South Vietnamese regime, to root out the Viet Cong guerrilla insurgency in the south, to combat the more conventional North Vietnamese Army (NVA) near the Demilitarized Zone between north and south, and to bomb military and industrial targets in North Vietnam itself. In public American military officials and members of the Johnson administration stressed their tactical successes and offered rosy predictions; speaking before the National Press Club in November 1967, General Westmoreland claimed, "I have never been more encouraged in the four years that I have been in Vietnam. We are making real progress...I am absolutely certain that whereas in 1965 the enemy was winning, today he is certainly losing." (New York Times, November 22, 1967).

Early in 1968 a massive coordinated Viet Cong operation - the Tet Offensive - briefly paralyzed American and South Vietnamese forces across the country, threatening even the American embassy compound in Saigon. With this the smiling mask slipped even further, inflaming the burgeoning antiwar movement. Although American soldiers didn't lose a battle strategically during the campaign, the Tet Offensive made President Johnson noncredible and historically unpopular, to the extent that he did not run for reelection in 1968.

Nearly 50 years after the campaign, the Tet Offensive continues to inspire impassioned and occasionally bitter debate. Was the large-scale Communist assault a strategic masterstroke that demolished American popular support for the war effort? Was it a catastrophic misstep that effectively broke the back of the Viet Cong guerrilla forces in South Vietnam? Did Tet expose the Johnson administration's optimistic pronouncements as a deliberate pattern of lies and obfuscations designed to mislead the American public about the true nature of the war? Perhaps the only proposition to win universal agreement is that the Tet Offensive represented a significant turning point. The conflict in Vietnam would continue for years after Tet, but it would never be the same.