As much as any other individual, Secretary of Defense Robert S. McNamara personified the American commitment in Vietnam. He was "the can-do man in the can-do society in the can-do era," David Halberstam wrote in The Best and the Brightest, and during the Kennedy and early Johnson years, he managed America's expanding involvement almost as if he were a desk officer. Whether slogging through Vietnam in army fatigues, spewing out statistics to demonstrate progress, or presiding at a press conference, map on the wall, pointer in hand, he epitomized what came to be called "McNamara's war." Whatever the difficulties of the moment, he exuded a certainty that promised ultimate success.
In fact, as has long been clear, his public confidence far outlasted the emergence of personal skepticism, and McNamara's tearful departure from the Pentagon at the height of the Tet Offensive in early 1968, as much as Lyndon B. Johnson's March 31, 1968, speech, marked the inglorious end of an era once bright with promise.
As the war aroused growing controversy in the United States, McNamara became a major target for critics from both left and right. Ignorant of his muted, tightly constrained internal dissent, doves viewed him as the ultimate technocrat, whose blind faith in technology and statistics plunged the nation into a destructive quagmire. Hawks, on the other hand, denounced with growing venom his interference with the military and his refusal to give it the freedom and tools to win an eminently winnable war.
For McNamara, Vietnam became a source of great personal torment. He left office quietly in 1968, declining out of a sense of loyalty to his president to air publicly his grave doubts. From that day forward, he refused to speak of Vietnam, even when he resurfaced in the 1980s during the debate over nuclear responsibility. He broke his vow of silence only briefly, at the time of the Westmoreland-CBS trial and on the eve of the Persian Gulf War.
His completion of the book he "never planned to write"