It's also true that he led raucous demonstrations in Washington, and participated in the "Winter Soldier" hearings. When he appeared before the Senate three months later, he spoke at length about reported American atrocities, attributing most of the specific allegations to veterans who had testified during Winter Soldier. Graphic references to rape, dismemberment and murder took up less than a paragraph of his lengthy testimony, but they certainly brought no credit on the U.S. military. Yet his eloquent words won bipartisan praise from the senators who listened to him.

Kerry didn't join the antiwar movement to indict his fellow soldiers; he often spoke with passion about the injustices done to them, both during the war and when they returned home to inadequate medical care and an indifferent government. His purpose was to prevent more of them from being killed, as he said over and over again.

He didn't try to absolve himself when denouncing the indiscriminate violence of the war. On "Meet the Press," he confessed that he had participated in "the same kind of atrocities as thousands of other soldiers have committed in that I took part in shootings in free-fire zones." But he felt strongly that U.S. military commanders and civilian policymakers were far more culpable for those atrocities than the men who obeyed their orders. Appalled by the civilian casualties in the "free-fire zones" marked out by their commanders, Kerry and other junior officers had gone to Saigon in January 1969 to complain to their superior -- and were of course ignored.

The free-fire zones, the use of napalm, the carpet-bombing and the assassination programs were all aspects of a guerrilla conflict that could not be prosecuted without killing thousands of civilians. Only by falsifying history -- and assuming that nobody will remember the truth -- can Kerry's right-wing critics claim that he somehow misled the country about what was happening in Vietnam. The smear depends on historical amnesia.

Last year the suppressed recollections of that disturbing past emerged again, when investigative journalist Gregory Vistica revealed wartime secrets long concealed by Bob Kerrey. Although the most incriminating details remain disputed, the former senator and Congressional Medal of Honor winner has admitted that he and Navy SEALS under his command massacred civilians during a nighttime raid on a hamlet called Thanh Phong in 1969. The ensuing debate over his conduct revived searing memories of My Lai, the village where hundreds of civilians were raped and murdered in March 1968 by U.S. soldiers.

In 1971, John Kerry told the Senate that if William Calley and the other soldiers who committed those atrocities were guilty, then so were the commanders who had made such crimes inevitable and then covered them up. "I think if you are going to try Lieutenant Calley then you must at the same time, if this country is going to demand respect for the law, you must at the same time try all those other people who have responsibility, and any aversion that we may have to the verdict as veterans is not to say that Calley should be freed, not to say that he is innocent, but to say that you can't just take him alone." Kerry's critics argue that My Lai was an isolated incident, but at least one celebrated general doesn't agree.

Secretary of State Colin Powell held a command position in the Army's Americal Division, which had included Calley's unit, and he was asked to investigate the earliest allegations about My Lai. He failed to uncover the massacre and was later accused of facilitating the coverup. Whether that accusation is fair or not, Powell knows what happened in Vietnam.

"My Lai was an appalling example of much that had gone wrong in Vietnam," he wrote in his bestselling autobiography, "My American Journey." "The involvement of so many unprepared officers and noncoms led to breakdowns in morale, discipline and professional judgment -- and to horrors like My Lai -- as the troops became numb to what appeared to be endless and mindless slaughter." For some reason, despite his loyalty to the president, Powell doesn't seem eager to attack John Kerry.