[The Reaper]

The first sign of siege was the massing of more than a thousand demonstrators in a few clusters around the city and around the compound, demanding that the C.P.A. leave Kut. Many in the crowds carried assault rifles and grenade launchers. John sensed, he said, that the protest at the compound might be a ruse, a cover for casing the site. Word came that the coalition-trained Iraqi police had abandoned their stations and checkpoints throughout the town, that the Mahdi fighters had claimed their weapons and uniforms. John had a core team of three Triple Canopy gunmen. There were about 40 Ukrainian coalition troops posted at the compound. The Iraqi guards employed by Triple Canopy were already starting to quit and to flee.

John declared ''lockdown'' and waited for whatever would come. Civilians strapped on their flak jackets and bulletproof vests. They prepared to retreat to a central spot within the hotel, a last point of defense, if the compound's perimeter was overrun. Warnings filtered in of car bombs set to strike. Through the night, two cars seemed to be casing the gates. Morning brought the sound of gunshots around the town -- and the ominous realization that the area just outside the compound was now desolate. Gunfire and rocket-propelled grenades started to hit around noon. The assault came from nearby, as close as the buildings across the street. It came from all sides. Mortars crashed in. A grenade exploded into a C.P.A. Suburban; the vehicle was consumed in flames. ''1740: Mortar fire has increased from across the river,'' reads a minute-by-minute account kept by a civilian contractor. Windows shattered; large fragments cracked from building walls; vehicles were ripped apart.

The enemy barrage of artillery and small arms surged and slackened and surged again. ''Throughout the battle, the commander of compound perimeter defense by de facto is John,'' states another contractor's hour-by-hour report. John climbed to the hotel roof to direct return fire. The three Triple Canopy gunmen manned the towers. Successive shifts of Iraqi guards had by now flooded out the gates after one was slightly wounded and a translator spread the rumor that the Americans planned to abandon them all to their deaths. Just two local soldiers remained; John put them on a machine gun. For hours the Ukrainians battled relentlessly; when they ran low on ammunition, John resupplied them with Triple Canopy rounds, the minute-by-minute account relates. He sent a fourth Triple Canopy soldier, a young dog handler who'd never seen a moment of combat, to race from tower to tower, taking bullets and water to the other T.C. fighters, who, John said, ''slung lead like you wouldn't believe,'' 2,500 rounds, he guessed. Triple Canopy's bomb-sniffing dog was left tied in the hotel and howled every time a mortar exploded.

On the roof and rushing through the compound between blasts, John juggled three radios and a satellite phone between his hands and combat vest pockets. None of the contingents he needed to speak with -- Triple Canopy; the separate company that handled the governorate coordinator's personal security (and that had pulled back to protect him within the compound); the civilian contractors; the U.S. military liaison in another town -- used the same communication system. He implored the military to send attack aircraft to scatter al-Sadr's men, who probably numbered 200 to 400.

The battle flared through the night. Heavy machine guns opened up from across the river. ''2200: There is an air-lift evacuation plan being put together.'' Two hours later: ''We were advised by T.C. that the air evacuation was scrubbed'' -- the odds of a helicopter being shot down while landing or lifting off were too high. An American plane at last arrived, its canons spewing shells. The militia went quiet, but then: ''0100: The hotel is hit several times and the building shakes from the impact. This fire seems to be the worst yet of the engagement.''

There appeared to be no escape; John figured the defense might be finished; on his radios and satellite phone he tried to keep his voice controlled, to keep his words, as he recounted, ''on the level of an information exchange.'' U.S. helicopter gunships then flew overhead. They held fire, but the enemy took cover again. And near dawn, in the lull, John and the Ukrainians carried out an order from the main C.P.A. headquarters in Baghdad that everyone should drive out of the compound, no matter what the risk in exposing themselves. They went in a mix of armored cars and open-sided trucks. ''Every turn you made, you didn't know,'' John said. He waited for mortars and R.P.G.'s to annihilate them. But the gunships tracked their route. No enemy fire came; they reached the closest coalition base; the civilians and soldiers of the compound had survived the battle without a serious wound.

The same week, a hundred miles to the west in the town of Najaf, eight private soldiers from the Blackwater company fought al-Sadr's Mahdi Army, stopping them from overrunning the C.P.A. headquarters there. The Blackwater men went unscathed. But just across town from John during the Kut fighting, the Mahdi Army attacked a building that housed five gunmen from the Hart Group, a British firm protecting the reconstruction of Iraq's electrical grid. The five were wounded, and one, pinned down on the building's roof in a firefight, bled to death.

A week earlier, four Blackwater soldiers, escorting a kitchen-supply truck to a U.S. military base, were ambushed and shot by insurgents in Fallujah -- their bodies roped to the back of a car and dragged through the streets, set on fire, torn apart and put on display, dangling from a Fallujah bridge. At the time, the Fallujah killings seemed notable not only for their brutality but also for the fact that private security men had been the victims.

Yet private security men in Iraq are embattled constantly. Between January and August 2004 (the last period for which the company has compiled figures), Triple Canopy teams came under attack 40 times, in incidents ranging from incoming rounds of rocket-propelled grenades to assaults lasting at least 24 hours. And the count of 40, I was told by the company's director of operations, represented only attacks in which Triple Canopy fired back. Six to eight times that number of assaults -- from sprays of enemy bullets to mortar fire -- had gone unrecorded, a company spokesman estimated. The frequency of attacks remains about the same now. The style has shifted away from assaults like the one at Kut, but guerrilla ambushes are on the rise.

It is impossible to say exactly how many private security men have been killed in Iraq. Deaths go unreported. But the figure, according to Lawrence Peter, is probably between 160 and 200. That's more deaths than any one of America's coalition partners have suffered.

"Some people will tell you they're here for Mom and apple pie,'' a private security man with another company told me. (He didn't want his or his company's name printed, he said, because neither his colleagues nor the industry in general think kindly of conversations with the media.) ''That's bull. It's the money.''

We sat between low concrete buildings at Triple Canopy's Baghdad base. The roofs are four feet thick and specially layered to absorb major blasts. The base sits within the Green Zone, behind high walls that divide the coalition's vast self-delineated borough from the severe danger of the rest of Baghdad. But the zone, as the people living and working there like to say, is these days less green than almost red: mortars rain in.

The man's company put him up at Triple Canopy's freshly built complex, with its pristine dining hall and ramshackle gym, its guard towers and long shipping container full of ammunition. The base is large enough that other outfits can rent rooms. Triple Canopy has come a long way from its haphazard beginnings. Its current contracts in Iraq, mostly with the U.S. Department of Defense and the State Department, are worth almost $250 million yearly. And having succeeded in Iraq -- Triple Canopy hasn't had a single worker or client killed -- it has just been named one of three companies that will divide up $1 billion annually in newly created protection work with the State Department in high-risk countries around the world.

But the private security man I sat with wasn't talking about windfalls on that level. He was talking about his own income. ''I'm richer than I've ever been,'' he said. ''I'm not in debt to nobody.''

He had jowls and loose swells of flesh beneath his T-shirt. ''Don't let the package fool you,'' the ex-Delta colonel who introduced us had told me. ''He's a commando from way back.'' After a career in Special Forces, the man said, he hadn't seemed able to survive in the civilian world. Work in construction fell apart. He drank heavily. He took a job as a cashier in a convenience store -- ''till I found out I had to smile at the customers.'' He laughed ruefully at his inability to adapt. But now, when his 16-year-old son sent him an e-mail message from back home in South Carolina, with a picture to prove that he'd mowed the lawn the way his mother had asked, he could buy the boy some tech equipment as a gift. ''I'll stay until this is over,'' he said. ''The money's too good.''