Doubleday. 416 pp. $27.95

From all sides, chaos. The pop-pop-pop of rifle fire. The whump-whump-whump of mortars. Men screaming. The air thick with a primal mix of urine and adrenalin and blood lust. Confusion. Up is down, left is right. Shadows running - but wait, shadows or the enemy? Friend or foe? No time to ask, just shoot. Just shoot and hope you didn't hit the wrong person.

It is called friendly fire. Is there a more ironic oxymoron?

Killed by one, or some, of your own. Killed by mistake, usually. But killed nonetheless.

And then comes the tricky part. Piecing it together. And assigning blame. Rarely is it simple. Because in war, as the Greek tragedian said, the truth is always the first casualty.

To which the author, Jon Krakauer, amends: "Chaos is indeed the normal state of affairs on the battleground, and no army has figured out a way to plan effectively for, let alone alleviate, the so-called fog of war. When the military is confronted with the fratricidal carnage that predictably results, denial and dissembling are its time-honored responses of first resort."

And later, he adds: "Military investigations of friendly-fire incidents have a well-documented history of obscuring the truth more often than revealing it."

In his latest book, Where Men Win Glory, Krakauer buttresses his point with the saga of the most famous victim of friendly fire of our time, Pat Tillman, the professional football player who walked away from certain riches because he felt a moral obligation to his country after 9/11.

A member of the Black Sheep, the Rangers of the Second Platoon, Tillman perished on a hillside in Afghanistan at precisely 6:46:15 p.m. on April 22, 2004, when three rounds from an automatic weapon struck him in the forehead, just under his helmet.

Friendly fire, Krakauer contends, and then sets out to prove it.

Almost instantly, according to Krakauer, the campaign was launched to portray Pat Tillman as a hero and to cover up what actually happened.

It is as though Tillman himself had a premonition of the web of deceit and concealment that would ensue, for as he told an Army buddy late one night: "I don't want them to parade me through the streets."

Which is precisely what happened initially. He was viewed by the military as a propaganda coup, useful in winning flagging support for a polarizing war.

He came to the military a ready-made super patriot, lauded by many in the media (your humble servant among them) for his extraordinary selflessness and sense of duty and obligation. Tillman, who was a devastating hitter, played safety for the Arizona Cardinals, who offered him $3.6 million over three years. Instead, he changed uniforms, for that of a Ranger, for $1,290 a month.

His was no act, Krakauer says. His patriotism was genuine. No one was heard to offer to change places with him.

There was a strong streak of the daredevil in Tilman. He was forever taking risks, jumping off whatever cliff was handy. The author is of the same bent, by the way - he is an intrepid climber of mountains himself and chronicled his conquest of Mount Everest with the acclaimed Into Thin Air. For this book, he went to Afghanistan, twice, and eschewed staying in the rear, preferring instead to go along on patrols.

He writes with the certitude and assurance of a man who has rooted his way through mounds of documents, journals, letters, interviews, and has gone to the front to see for himself where Tillman perished.

Krakauer spends a lot of pages telling us what a complex and driven man Tillman was, and at times it is slow sledding, as it is with portions devoted to the politics of the time. But he always finds his way back. You are left with outrage and, finally, rage.

The account of Pat Tillman's final hours is harrowing, and, at times, grisly. But it also resonates with what seems to be the unmistakable ring of truth.

What is especially disquieting is the thought that there is no reason to believe that this cannot be repeated.

Or hasn't already been.