Army Pfc. Jason N. Lynch was taking his one-hour shift behind a Humvee-mounted .50-caliber machine gun when the AK-47s started crackling again, just before dusk. As he responded by raking the source of enemy fire, sticking his head and torso out the roof to aim, a single 7.62mm round found a mortal opening just below Lynch's body armor and ripped into his right side.

Lynch, 21, a 6-foot-2 St. Croix islander who reveled in reggae music and yearned to return to his Caribbean home, immediately slumped down into the Humvee, his comrades in Charlie Battery recalled, and he shouted out to no one in particular: "Ah! I'm hit." Those words -- uttered Friday at 6:50 p.m. in Buhriz, a rebellious, date-growing village about 35 miles northeast of Baghdad -- were the last they heard him say.

Although medics struggled to save his life, the internal bleeding was massive, they said, and Lynch swiftly went into shock. Within an hour, the young soldier had joined the slowly but relentlessly growing list of American troops killed in the occupation of Iraq.

Of the 842 U.S. service members who have died in Iraq since the invasion 15 months ago, 622 were killed by hostile fire, according to a Pentagon tally. The largest part of that combat death toll, 513, has come since President Bush's declaration on May 1 last year that major combat was over. These troops died at the hands of Iraqis and a sprinkling of foreign Arabs fighting the U.S. occupation and seeking to derail the Bush administration's plan to transform the country.

Most of the 513 have died one or two at a time in roadside bombings or skirmishes too small to make headlines back in the States. But for those involved -- the soldiers who fell, the men and women who lived through the battle, the families left behind -- each casualty has been a large-scale tragedy, filled with their sweat, their rage, their courage, their blood and, ultimately, their tears.

When Lynch sank mortally wounded from his machine-gun perch, Pfc. Kyle Lautenhiser, 20, of Fort Wayne, Ind., had just trotted up to the Humvee to relieve him. Along with those in the vehicle, Lautenhiser recalled, he pulled Lynch out a back door, laid him on the ground and called for medics. Then, Lautenhiser said, he jumped into the Humvee, grabbed the machine-gun handles and sprayed several hundred .50-caliber bullets toward the two-story building across the road where the AK-47 assault-rifle fire had come from.

By then the medics, including Spec. Michael Miranda, 21, of Roma, Tex., and Pfc. Stu Eubanks, 22, of Lakeland, Fla., had arrived with emergency first-aid equipment and a litter. Hunching down to avoid the rifle fire, which still had not been suppressed, they ran their hands around Lynch's torso to assess his wounds. What they found, they recalled, was one bullet hole and signs of heavy internal bleeding.

Sliding Lynch onto the litter, they carried him back to the command center and casualty collection point that had been set up nearby in a building their unit had been ordered to capture. There, Miranda said, they ripped off Lynch's body armor and other gear. Fighting to find a vein, they stuck a needle into his arm to give him intravenous fluids, seeking to compensate for the blood loss. As they worked feverishly, trying all the tricks of their training, Lynch's pulse came and went.

"About a minute into it, he started going into shock," Eubanks recalled three days later, sucking on a cigarette in Iraq's stifling evening heat. "We were cutting clothes off him left and right. And when he went into shock, his breathing started closing off. So we had to bag him" -- fit him with a respirator.

Although Lynch's condition was still not stable, Miranda said, the medics decided he had to be moved to a field hospital. About six minutes had elapsed since he was hit, and he did not look good. So the medics loaded him into a Bradley Fighting Vehicle -- armored to withstand the persistent gunfire -- and transported him to a pickup point for transfer to a Humvee ambulance and a 20-minute drive to the Army's regional headquarters at Forward Operating Base Warhorse.

As they were opening the Bradley's back hatch and moving Lynch to the waiting ambulance, a rocket-propelled grenade hit nearby, Eubanks said. A roadside bomb exploded near the ambulance as it approached, forcing it to run on flattened tires designed to function with or without air, the unit commander recalled.

Sgt. Maria Kammerer, 21, of Houston, was in the back of the ambulance. As they drove toward Warhorse at about 45 mph, she said later, Lynch seemed to respond to stimuli. He swatted at the uncomfortable breathing bag in his mouth and complained he could not breathe. He nodded his head when she asked if he was still with them. And, in a triumph of military bureaucracy, Lynch was able to give Kammerer the last four digits of his Social Security number to get the paperwork started for his medical care on arrival.

Within a half-hour of his delivery to the hospital, however, Lynch died, Kammerer said. The paperwork from then on would be about his death, a death far from St. Croix, on a dusty road near a dilapidated two-story house surrounded by date palms, a death on a fertile agricultural plain of east-central Iraq where some men are determined to kill as many U.S. soldiers as they can.

Holding the 'Strong Point'

"Our mission was to go in, take the strong point, and hold it," said Capt. Matt Davenport, who commands Charlie Battery, part of the 1st Infantry Division's 1st Battalion, 6th Field Artillery, and who led the young gunner into battle.

Davenport, 36, of Deerfield, Va., said Lynch was normally the machine gunner on his command Humvee. But last Friday, during a day of incessant clashes that began before dawn, Davenport had pulled his vehicle close to the command post for use as a communications platform. So Lynch made himself useful by taking rotating shifts on a machine gun mounted on another Humvee posted outside the command compound.

The command post was set up in a building and surrounding compound used by agricultural officials during Saddam Hussein's rule. Davenport's team had been ordered to seize it because insurgents were using it to fire on patrols. It was one of many such spots in and around Buhriz, a hornet's nest on the edge of the agricultural hub of Baqubah, the capital of Diyala province.

Even before the 1st Infantry Division pulled into this region in late March, Buhriz was a trouble spot. A combination of tribal hostility to foreigners and intricately woven loyalties to the fallen Hussein government and its Baath Party network resulted in attacks on nearly every U.S. patrol that ventured into town.

Col. Dana J.H. Pittard, who commands the division's Baqubah force, said he was determined to end that. Using a mix of economic development projects and aggressive military patrols, he made it clear to village and tribal leaders that he had money to spend on their community if they cooperated, but that attacks on U.S. forces would lead to bloody counterattacks.

A group of insurgents using Buhriz as their base made their intentions clear last week by firing rocket-propelled grenades as U.S. officers met with the mayor. So Pittard's U.S. occupation forces went into town, waited for an attack and responded hard when it came.

"We waxed them," he said in an interview.

Davenport's assignment to seize and hold the agricultural building was part of the crackdown. Because his field artillery unit had been retagged infantry to meet new needs in Iraq, Davenport said, he found himself commanding three motorized platoons with Humvees and a unit of M2 Bradley Fighting Vehicles instead of an artillery battery.

As the Americans approached in those Humvees and Bradleys, Davenport said, insurgents in the house across from the agricultural building hit them with AK-47 fire, RPG-7 rocket-propelled grenades and 120mm mortar shells fired in a direct line rather than the normal high arc. Sniper fire also pinged in occasionally from what his soldiers thought were three separate locations, he added.

For most of a 120-degree day -- 14 hours straight, Davenport remembered -- the soldiers traded fire with the insurgents, including the exchange that killed Lynch. The heat, even more intense in the vehicles, drove dozens of men into the command post for intravenous injections of fluid to counteract dehydration, the medics said. At one point, a grenade launched by U.S. troops hit a nearby wall and sent chunks of concrete flying back at them, wounding one soldier in the groin.

"And while all this was going on, the guy who was direct-laying the mortars was walking the mortar rounds toward us," Davenport said.

Such missions are expected to continue for months. The U.S. military has expressed hopes of lowering its profile in Iraq after the partial transfer of power to an interim Iraqi government next week, but even so expects to continue routinely engaging in combat with insurgents.

Davenport said the clash Friday was not the worst experience he and his men had been through since arriving at Forward Operating Base Gabe, but it seemed like the longest, and for Lynch it was forever.

Empty Boots and Heavy Hearts

The soldiers of Forward Operating Base Gabe, a dusty expanse on Baqubah's outskirts, held a memorial service Tuesday to honor Lynch. A feeble breeze rasped in the eucalyptus leaves as the unit chaplain, Capt. Michael Jeffries, called attention to the grief of Lynch's family in St. Croix, and officers stepped to the podium one by one to eulogize him.

"We occupied the strong point because we knew then we would not have to chase down an elusive enemy," said the first to speak, Lt. Col. Steve Bullimore, 43, of St. Joseph, Mo. "We owe it to Jason, to his family, that his death not be in vain, that his sacrifice not in any way be diminished."

Lautenhiser, the soldier who had jumped up to take Lynch's place when he fell, joined the line with a simple message: "My name is Pfc. Kyle Lautenhiser," he said, "and I am here to tell you about a great person, and a real person. His name was Jason Lynch."

Lynch's beige combat boots were standing empty on display. The flak helmet he was wearing when he died was perched on his M-16 rifle, and his Purple Heart and Bronze Star were laid out for all to see. When the speechmaking was over, when taps was played, after the rifles were fired in a final tribute, officers and men filed past one by one to salute his photograph.

In the silence, several soldiers wept.

'Everything Just Froze'

Cpl. Evrod Folkes, 22, a native of Ocho Rios, Jamaica, who enlisted after moving to New York, said he and Lynch used to sit back, turn up the volume on their reggae CDs and dream of returning to their islands. Roommates and close friends, they talked of their families, their music, their hopes for a leave, but rarely about Iraq, he said. Like many enlisted soldiers here, Folkes said, Lynch regarded the pros and cons of the U.S. occupation as a subject above his pay grade.

"We didn't really talk about it," Folkes said. "We just talked about the leave coming up, about going home to see the family."

Lynch enlisted in the Army almost a year ago, Folkes said, but never explained why. "I guess he was bored of the islands," Folkes said, only a trace of Jamaican lilt remaining in his speech. "He wanted to travel."

Lynch left a memory with Folkes and his other friends of a man who kept quiet most of the time. He mostly spoke only when spoken to, they said, and tended to keep his answers short. The loping rhythm of reggae was what he wanted to hear, they recalled.

"He would just sit there and listen to it for hours," said a colleague and friend, Sgt. Steven Sherrod, 34, of Philadelphia.

Lynch's death took Folkes and his other friends by surprise. They had heard in radio traffic at the battle tracking station that he was hit, but their initial information, they recalled, was that he was alert and responding to medics. So they assumed he would be on the wounded list, nothing more, and maybe get transported back to the division's home in Germany for treatment.

"When they did the medevac, he wasn't bleeding or anything, so I thought he was going to be okay," Folkes said.

Then, after midnight, the real news came down. Lynch was dead. He did not get out of the field hospital at Warhorse.

"You couldn't hear nothing after that," Folkes said. "Everything just froze. . . . Everybody knows that can happen, but when it does, everybody wishes it could just rewind."

Folkes shared his memories of Lynch just outside the battle tracking station here, sitting in a plastic chair and looking straight ahead. He emphasized repeatedly how Lynch was looking forward to leaving soon to visit his mother. Just above his head was posted a list of those waiting in line for the two-week escape. Lynch's name was at the top of the list. He would have been the next to go.

Spec. Jarrod Matthews is comforted by Staff Sgt. Jason Bacon after a memorial service in Iraq for Pfc. Jason N. Lynch. At Forward Operating Base Gabe near Baqubah, Iraq, Spec. Jarrod Matthews hugs Staff Sgt. Jason Bacon during the Lynch memorial service. Army Pfc. Jason N. Lynch, 21, who was killed on Friday, enjoyed reggae music and yearned to return to his home in the Virgin Islands.