So far in the Gulf war, the main U.S. ground casualties have been the Marines accidentally killed by an Air Force pilot who thought their armored car was an Iraqi vehicle.

Military officials call it "friendly fire." They point out that mistakenly killing one's own troops happens in every war.

My father could attest to that. For him, a rifle company lieutenant in World War II, it occurred in August 1944 during the debacle of crossing the Meuse River in Germany. The Allies were making their final assault against Hitler. In a letter to my mother, my father wrote:

". . . we were cut off, {so} I took two guys out to try and sneak through about two miles of enemy territory where we thought another battalion might be. There was a shadow in the dark woods with a machine pistol -- hallmark of the German noncom. I said 'halt' and the pistol swung up. My shot threw him out into a patch of sunlight, and it was a GI with a tommy gun. He was the last survivor of F company, which had been cut up the night before by flame-throwing tanks.

"It was tough on me because we had to leave him to die. By luck I got a chance to come back later and find him still alive. Then he died the next morning, 10 minutes before I got a medic up to him with plasma. We were cut off and couldn't get out until then.

"Leaving him was the tough part, much harder to take than anything else in the war . . . I hesitated to write all this . . . It's not spectacular and occurs quite frequently . . . at least I didn't go to pieces as most of them do."

But then, he had been trained not to go to pieces, imbued as he was with the stoicism of an honorable schoolboy. Growing up, we children knew that the highest compliment from our father was that we were worthy of the men in E Company, his company. My father survived the war and went on to have much joy and laughter in his life. But even as a child I thought his eyes were always sad.

These days there is much more understanding of combat stress and its long-term consequences. Friendly fire is an especially horrific trauma of war. Usually the emphasis, understandably, is on the victim; but what about the perpetrator?

It's a phenomenon more common in civilian life than we tend to acknowledge. Just 10 days ago, an air traffic controller in Los Angeles was inadvertently responsible for the collision of two planes on the runway that killed 34 people. "I'm sorry. I'm sorry," she reportedly said after the crash. "How would you feel if your worst nightmare had come true?" one of her colleagues asked the Los Angeles Times. "This incident, this accident, could have happened to anybody, any of us."

Those who commit friendly fire in military or civilian life face a long personal quest for self-forgiveness. Society generally is sympathetic and doesn't blame them. But it's not that easy for the individual to overcome the crushing guilt.

In psychological terms, the worst thing to do is to repress these events as though they didn't happen. As a combat policy, it makes no sense to dwell on accidents. It is also disturbing for the public -- and for relatives -- to learn that their loved ones died by mistake.

Yet what makes sense to maintain military morale is counterproductive for those who inadvertently cause another's death.

"One pays a price for walling off guilt, walling off the trauma," said Richard C. Simons, a professor of psychiatry at the University of Colorado Health Sciences Center in Denver. "We see every day in VA hospitals and clinics soldiers suffering from the guilt they bear for certain actions that still haunt them."

But guilt doesn't have to be a destructive emotion, experts say. In appropriate amounts, it can be a healing force, helping people mature by accepting responsibility.

"People can't easily get over the stress of having done something terrible to another person," said Paul Fink, a past president of the American Psychiatric Association. "They have to work through the fact that they were not doing this with malice."

The catastrophes of combat or a plane crash are dramatic examples of personal trauma. But there are incidents of friendly fire in many people's lives: Car crashes that involve the death of a stranger, family members or friends; hunting accidents where brother kills brother; a shootout where a police officer hits a fellow officer or bystander; the mother who turns her back for a moment as her toddler pulls a pot of boiling water off the stove.

Some people take a lifetime to forgive themselves. It's a terrain where religion and psychiatry overlap and healing involves sharing the experience and making amends to the dead and the living.

For Ron Kovic, the hero of the film "Born on the Fourth of July," forgiveness came when he visited the family of the soldier he had killed by mistake in Vietnam.

For my father, that involved writing letters to my mother. For both of them, it was saving those letters and passing them on to their children and grandchildren so that they would know the truth about The Last Good War -- and about them.

"I'm so glad you're blowing off steam to me," my mother wrote to him. She was struck by his anguish. "Perhaps in a few years, you might be left with your original feeling, which was that you didn't want someone else to do your fighting for you," she wrote.

And so, my father came home with his medals and memories. In time, the war took its place among other unavoidable tragedies in his long life, a nagging reminder that fate is capricious and people are fragile.