I lost any illusions I might have harbored about combat being fair, humane, or sensible the very first time bullets whizzed toward me.

My First Cavalry outfit was ascending a ridgeline along the Ho Chi Minh Trail.

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Around us were fresh signs of enemy activity: scuffed trails, recently abandoned bunkers, half-filled rice bowls, and fresh bloody dressings. We were frightened.

Our spirits lifted when we heard a light observation helicopter buzzing our way, skimming the canopy of the jungle. It was one of ours, of course--the enemy had none of these. The efficient clatter of its rotors reminded us that America's stupefying technological strength was everywhere, even at Vietnam's primeval border with Laos. Then suddenly, it veered in our direction, swooped down, and fired its mini-gun on our troop line. In seconds--some of us were still waving our rifles and smiling skyward in greeting--a half dozen of our men were hit. Some of them were badly wounded.

It took me that long to figure out that in a war zone, you can't trust anyone, or anything, even your supposed comrades and friends. The reality of combat undermines our notion that wars can be fought with rules, predictable behavior, or fine moral principles.

I arrived in Vietnam a half year before Robert Kerrey arrived. I spent less than six months there, but that was plenty of time for me to learn to distinguish the horrifying noises various shards and rounds of metal made as they whirred and zipped my way. I was wounded twice (though much less severely than Kerrey, who lost most of a leg). My unit lost men to mines, booby traps, punji pits, and ambushes. The experience didn't teach moral equilibrium. Over time, warfare's unpredictable but steady moral arc takes most people down. You need to be strong and lucky to survive combat, and even luckier to survive morally intact.

Here's what I mean.

Once my Cav company was attacked by North Vietnamese sappers. Astonishingly brave demolition experts infiltrated our lines through a neighboring village, did their bloody work, tossing satchel charges into our bunkers under the cover of their own mortars, which pinned us down. Then they crept back through our

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barbed wire, dragging their wounded and dead with them. When they left, six of our guys were dead and 18 of us, including me, were wounded.

The next morning, we went back through the village, looking for reprisal. We found no one. We took out our fury on village shelters. After yelling for anyone who might be inside to give themselves up and come out, hearing nothing, we threw grenades. We heard no cries--so unlike Bob Kerrey, I have been spared the shrieks of ghosts. Still, I came close to a life of self-recrimination. What if there had been people inside, kids or women who were too terrified or ignorant of English to respond?

Later, I became an adviser to the South Vietnamese Regional Forces. One morning before dawn, we moved into a string of villages flanked by rice paddies. We knew that the people in the villages were heavily sympathetic to the Communists. It was a free fire zone. Anyone found moving outside their huts at night could be considered VC or NVA.