An unsuccessful effort to defend South Vietnam from communist North Vietnam's invasion, the Vietnam War (1964–73) proved deadly. Probably 500,000 to a million North Vietnamese, 350,000 South Vietnamese, millions of civilians, and 58,000 Americans died.

Blacks, as did most citizens, were divided over American intervention. However, 30 percent of eligible blacks, compared to 18 percent of whites, were drafted in the 1960s. African Americans composed 12 percent of Vietnam combat soldiers and 20 percent of fatalities between 1966 and 1969. Such racial and class disparities steadily united the civil rights and antiwar movements. Black Muslim imam Malcolm X condemned the Kennedy administration's military policy in 1964. The next year, speaking before a Washington Monument rally, Student Nonviolent Coordinating Committee (SNCC) activist Bob Moses criticized the troop buildup. In 1967 Martin Luther King, Jr. opposed the war, renouncing US militarism, racism, and injustice. When the National Guard killed six college protesters in 1970, a majority of Americans had turned against the war.