The Vietnam War

After France lost its colony in 1954, Vietnam split at the 17th parallel: a communist North under Ho Chi Minh, a US-backed South under Ngo Dinh Diem. Washington saw this through the domino theory, the fear that if Vietnam fell to communism, neighboring countries would fall too. So the US sent money and a few hundred military advisers under Eisenhower and Kennedy. In August 1964, after reported attacks on US ships in the Gulf of Tonkin, Congress passed the Gulf of Tonkin Resolution, giving President Johnson broad power to wage war without a formal declaration. Troop numbers then climbed fast: about 23,000 in 1964, 184,000 by the end of 1965, over 500,000 by 1968. Each year's increase looked like a reasonable next step, not a decision to fight a decade-long war, which is exactly the point: escalation was incremental.

The North countered superior American firepower with the Ho Chi Minh Trail, a network of paths and roads running through neighboring Laos and Cambodia, letting troops and supplies move south while dodging the US-controlled battle lines in Vietnam itself. This let the North sustain a long guerrilla war despite being outgunned.

The Tet Offensive of January 1968 brought coordinated communist attacks on cities across the South, including Saigon. American and South Vietnamese forces beat back every attack and inflicted devastating losses on the attackers. But televised images of fighting at the US embassy shattered the Johnson administration's claims that victory was near. Tet was a military defeat for the North and a strategic win, since it turned American public and media opinion decisively against the war, setting up Nixon's slower withdrawal and Vietnamization that follow this topic.