At the beginning of the 1960s, few Americans could have identified Vietnam on a map or explained why the United States might be involved in the small southeast Asian nation that lay halfway around the world. But by the end of the decade, U.S. involvement in Vietnam had cost thousands of American lives and embroiled the nation in a furious and sometimes violent debate over U.S. foreign policy. A growing antiwar movement in the United States drew public attention to its arguments with public protests and campaigns to change policy. By 1968 these protests had helped drive President Lyndon B. Johnson (1908–1973; served 1963–69) from office.

The roots of the conflict in Vietnam stretched back to the nineteenth century, when French colonizers took control of an area they called French Indochina, which included the modern countries of Vietnam, Cambodia, Laos, and other portions of Asia...