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The Vietnam War Explained

How a Cold War theory pulled America into its longest 20th-century war — and what it cost at home.
Atmospheric illustration of the Vietnam War era

The United States did not decide to fight in Vietnam on any single day. It arrived there by increments — a few hundred advisers, then a few thousand, then a congressional resolution, then half a million troops — each step justified by the one before it. Behind every increment sat a single idea: that if one nation in Southeast Asia fell to communism, its neighbors would follow. That idea, the domino theory, turned a distant civil conflict into a test of American resolve, and the test ran for two decades.

This guide follows the war from its Cold War roots through escalation under Kennedy and Johnson, the home-front rupture of 1968, and the long, bitter withdrawal under Nixon. The entries below are arranged as a timeline, grouped by phase. Read together, they trace how the policy of containment met the limits of American power abroad and the limits of public patience at home — and how the gap between official optimism and battlefield reality, exposed in leaked documents and televised protest, reshaped the relationship between Americans and their government.

The Cold War Logic
Containment
The postwar strategy of halting communist expansion supplied the rationale for every later commitment in Southeast Asia.
The Domino Theory
The premise that one nation's fall would topple its neighbors, used to justify intervention from Eisenhower onward.
The War Itself
Vietnam War
The full arc of the conflict, 1955 to 1975 — the spine this timeline annotates.
Kennedy and the Advisers
John F. Kennedy
Kennedy deepened the American footprint, raising the adviser count into the thousands before his death in 1963.
Johnson's Escalation
Gulf of Tonkin Resolution
The 1964 resolution that handed Johnson near-blanket authority to wage war without a formal declaration.
Lyndon B. Johnson
The president who poured ground troops into Vietnam and watched the war consume his Great Society and his presidency.
The Home Front Turns
The Counterculture of the 1960s
The cultural revolt of the decade drew much of its energy from opposition to the draft and the war.
Muhammad Ali
The heavyweight champion's refusal of induction in 1967 made the antiwar stand a national headline.
1968: The Year It Broke
Robert F. Kennedy
His antiwar campaign for the presidency ended with his assassination in June, deepening the year's sense of unraveling.
Election of 1968
Nixon's narrow win, won partly on a promise of "peace with honor," reset the politics of the war.
Chicago 1968
The Democratic convention where antiwar protest and police clashed on television, splitting the party.
Nixon's War and the Backlash
Kent State Shootings
The 1970 killing of four students by the National Guard turned campus protest into a national crisis.
Richard Nixon
The president who widened the war into Cambodia even as he pursued withdrawal and ended the draft.
Pentagon Papers
The 1971 leak that documented years of official deception about the war's conduct and prospects.
The Long Exit
Détente
Nixon and Kissinger's easing of Cold War tensions reframed Vietnam within a wider diplomatic strategy.
War Powers Resolution
Congress's 1973 attempt to reclaim its war authority, passed in direct reaction to the Vietnam experience.

For the wider standoff that framed the war, see The Cold War: A Complete Timeline. To place Vietnam alongside the nation's other conflicts, see Every U.S. War and Major Conflict Explained.

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