A Pattern of Escalation.

U.S. forces stationed in Vietnam reached average levels of 389,000 in 1966, 485,600 in 1967, and 549,500 in 1968. At the height of this expansion the United States was employing 40 percent of its combat-ready divisions, 50 percent of its tactical airpower, and 33 percent of its naval forces in Vietnam. Throughout this expansion of the war, the administration continued to express its conviction that a victory was possible.

The Tet Offensive.

This optimism seemed overstated to the American public after the Vietcong and the North Vietnamese launched an unexpected offensive on 30 January 1968 during Tet, the Vietnamese holiday celebrating the lunar new year. Although the offensive was defeated militarily, it created the perception that the war would not be won as easily as U.S. officials had led the public to believe. On 27 February 1968 Westmoreland requested an additional 208,000 troops, but on 22 March the administration ordered...