Almost more than Nixon, more than LBJ, Robert McNamara came to personify America's tragic engagement in Vietnam. "McNamara's War," Senator Wayne Morse had called it in the spring of 1964, a description that the then cocky former "whiz kid" and Ford Motor Company president turned Pentagon chief had enthusiastically embraced. He was "pleased" to be associated with Vietnam, he replied, and would do "whatever I can to win it."

By the time he left office in 1967 -- effectively fired by President Johnson for opposing the bombing and troop escalation strategy that he himself had blessed -- half a million American soldiers had gone to war and Vietnam had been carpet bombed. As he did quiet penance as president of the World Bank, 58,000 American soldiers' lives would ultimately be lost. But still the war would not be won.

McNamara spent the next 40 years in atonement, asking in his 1995 belated, best-selling memoir five questions he said he wished he and others had asked from the start: would, for instance, the fall of South Vietnam really trigger the fall of all Southeast Asia? Would that pose a grave threat to America national security?

By 2003, the five questions had ballooned into "11 lessons" about the use of power. The Oscar-winning documentary about him, "The Fog of War," was being screened as the United States was invading Iraq.

But these anguished, belated mea culpas satisfied few. National security hawks considered him a traitor, and for many anti-war activists, his conversion to their ranks and his quasi nuclear pacifism came too late.

Some of those who had worked with him in government were more forgiving. As Ted Sorensen, the speechwriter and adviser who worked with McNamara in the Kennedy and Johnson administrations, reminded the Associated Press, most senior government officials "don't admit error, ever.''

But they can and should ask the kind of policy questions he posed after it had long ceased to matter. His sad fate reminds us of the enormous potential consequences of failing to do so.

Judith Miller is a writer and FOX News contributor.