RAMADI, Iraq—The first of 2nd Lt. John T. Wroblewski's three Humvees slowed as it entered the Ramadi marketplace where the insurgents were waiting.

At the wheel was Lance Cpl. Kyle Crowley, 18, of San Ramon, Calif. With him in the unarmored green Humvee were radio operator Lance Cpl. Travis Layfield, 19, of Fremont, Calif.; Pfc. Christopher R. Cobb, 19, of Bradenton, Fla.; Lance Cpl. Anthony Roberts, 18, of Bear, Del.; Navy Petty Officer 3rd Class Fernando A. Mendez-Aceves, 27, of San Diego, a medic; Staff Sgt. Allan K. Walker, 28, of Lancaster, Calif., and Lance Cpl. Deshon E. Otey, 24, of Louisville, Ky. In the back, manning the machine gun, was Pfc. Ryan Jerabek, 18, of Oneida, Wis.

Most of them were following in their family's footsteps. Crowley's great-grandfather had been a World War II Marine. Layfield's maternal grandfather was a Seabee in World War II. Cobb's stepfather had served, and so had Roberts' dad. Mendez-Aceves had listened to his great-grandmother rocking him to sleep humming soldiers' marches. Men in Walker's family had served in virtually all of America's wars. Jerabek's father, Ken, had served in the Army during Vietnam.

Ryan Jerabek had pre-enlisted in the Marines with his friend Mike Andrews when he turned 17. "He had the sweetest smile," said Faye Girardi, one of his teachers at Pulaski High School, who thought Ryan was "too gentle" to become a Marine.

Ryan's sense of humor survived boot camp: He laughingly called his military-issue glasses "BC glasses"—birth control glasses—because they were so effective at keeping girls away.

When Travis Layfield was about 9, his family visited an air show at Moffett Field in Mountain View, Calif. "He saw kids in uniform and he said, `I want to sign up,'" said his sister, Tiffany Bolton. "That's where it started."

Cobb's minister, John Marlow, an Army veteran, had taught 8-year-old Chris what it meant to be a soldier.

"We were talking and I said, "Chris, I was in the U.S. Army and I tried to be a good soldier," remembered Marlow, now 70. "Chris looked me in the eye and said, `Well, I will be a good soldier.'"

Roberts had stood over his father's casket, a boy of 13 staring silently at the man he had adored. Tony went on to star in karate, baseball, volunteer service for the elderly, even the summer reading program. He was handsome and, said his ROTC teacher, Maj. Daniel Alvarez, "he had the ladies after him all the time."

The driver of the Humvee, Kyle Crowley, had been something of a troubled kid who drove around San Ramon in the San Francisco Bay area in a 1980s Cadillac he'd inherited from his grandmother. He signed up in a pre-enlistment program when he turned 16, over the objections of his father, Mark, a sheet-metal worker who'd raised Kyle by himself from age 4.

Kyle slapped a Marine Corps sticker on the back of his car. He hung American and Marine Corps flags in his room, and he wore Marine T-shirts to school.

When Cobb came home from boot camp to Bradenton, Fla., he wore his uniform back to Bayshore High School, where his teachers remembered "a quiet kid in the back of the class."

"He was so proud," said Richard Jorgensen, who taught Chris' orchestra class. "He had just finished basic. He seemed more relaxed. I think the Marines gave him a sense of identity. A sense of pride that he didn't seem to have before."

Navy medic Fernando Mendez-Aceves had been a scrawny boy, but boot camp had changed him, too. His biceps grew so big that he had to wear oversize shirts. At the Naval Medical Center in San Diego they called him Rocky, the Muscle Man or Hulk. He volunteered for duty with the Marines in Iraq because he didn't want his combat training to go to waste.

They called Staff Sgt. Allan Walker, at 28 one of Echo Company's senior noncommissioned officers, the Beast. Six feet 2 and 230 pounds, he'd played high school football and flipped burgers in the Mojave Desert town of Palmdale, Calif.

But Walker "had all these little twists and turns," said Jim Root, his old football coach and friend. Walker was a high school jock who also hung with the drama kids, and a rebellious teenager who wore punk rock T-shirts and spiked hair but loved poetry.

"The Marine Corps was his intervention program," said his father, Kenneth Walker.

When the war came, Allan Walker, too, volunteered to go. "How can I teach a corporal how to take a hill if he's been there and I have never?" he asked his father. "How can I teach men to fight if I've never been to battle?"

As the green Humvee neared the T-intersection at the Ramadi marketplace, the insurgents hidden on the rooftops opened fire. Bullets plowed through the windshield and the metal doors. Crowley, the driver, was killed, and the truck canted sideways. Jerabek opened up with his machine gun, but he, too, was quickly cut down.

Deshon Otey leapt out of the Humvee and began firing from behind a low wall. The others stayed in the truck and were quickly gunned down.

"We all took cover," Otey said. "There was firing coming from all directions. They were shooting AK-47's, RPK machine guns and rocket-propelled grenades."

Mendez-Aceves, the Navy medic, was killed next to Walker, apparently working to save the sergeant's life.

Wroblewski was behind them in the second Humvee. He was hit in the face by a bullet that smashed through the radio handset he was holding.

As soon as Royer's reinforcements moved toward the firefight in the marketplace, they came under fire, too.

Running toward the cover of nearby houses, Royer yelled at his radio operator to keep up with him: "Suck it up, find it ... find it, son, your Marines are being shot at!"

Royer's Iraqi translator, a man everyone called "007," was smiling as he ran, in tan sandals, a sleeveless jogging outfit and a navy blue T-shirt that said "Operation Iraqi Freedom" across the front. Wearing neither a helmet nor a protective vest, he was blithely fatalistic: "Inshallah," he said. God willing.

Royer and his men reached the relative safety of a house. Other Marines were already there, and so was an Iraqi family, huddled in the living room. Bullets smacked into the side of the house as Royer led his Marines up the stairs to the rooftop to begin returning fire.

Royer got on the radio and called for air support, but the helicopters were in action elsewhere, circling over firefights in the center of the city.

Royer sent a team to silence the insurgents' Russian-made machine gun on the corner rooftop but by the time the Marines got there, the Iraqi machine gunners had vanished, leaving only a pile of spent shell casings.

Five Iraqi men walked along the intersection. "Do they have weapons? Do they have weapons?" Royer yelled. Marines opened fire, and the men scattered out of sight. The Marines saw cars and vans approaching the area, then slowing down and turning back, picking up walking men. Were they retreating fighters? The Marines couldn't tell.

Other Marines entered the marketplace and began removing the bodies of the dead Americans from the green Humvee. Royer and his men joined them.

Remnants of cotton and paper trauma supplies littered the ground. The bed of the truck was littered with empty water bottles and exploded green packages of meals-ready-to-eat, mixed among brass shell casings. The rectangular top handle of an M-16 was sheared off in a pile of debris. Blood and water and diesel oil drained into the ground.

A Marine passed by slowly, carrying the body of a fallen brother on his shoulder. He gently placed the heavy, dark green bag in the back of a Humvee.

A pair of military-issue eyeglasses lay smashed on the ground by the lead Humvee, blood drying on the right lens. They were machine gunner Jerabek's birth control glasses.

"I talk with some of the other guys in the platoon about what happened, but it still hurts," Otey, the lone survivor in the green Humvee, said later. "Every time I walk into our living space I see the empty racks (bunks). Those were guys I used to talk to about my problems. Now I don't hear their voices anymore."

Otey, 24, was killed two months later on a rooftop in Ramadi with three other Echo Company Marines.

Taking the rooftops of nearby houses that April day, the Marines gained control of the intersection, and the sound of gunfire died down.

A sergeant from Combat Outpost arrived and said he'd seen Wroblewski and that Lt. Ski would be OK.

He was wrong. Wroblewski died while a helicopter was evacuating him. An enemy bullet had severed an artery, and the medics couldn't control the bleeding.

The bodies of four Iraqis lay in the street, one beside a red-and-white taxi. Royer stood over one of the dead men for a few seconds, then stepped over the body. The translator everyone called "007," trailing Royer, kicked the body hard and muttered, "Bastard."

The evening light was growing softer, cooler.

Pfc. Eric Ayon, 26, of Arleta, Calif., climbed behind the wheel of the green Humvee and tried the ignition. Nothing. A rocket-propelled grenade had pierced the engine compartment. Photographer David Swanson of The Philadelphia Inquirer, who was traveling with Echo Company, took pictures of Ayon sitting behind the Humvee's shattered windshield.

Ayon had wanted to join the military since the days when he ambushed his sister's Barbie doll with his G.I. Joe. He told everyone he was going to be a Marine. He told his co-workers at Mid-Valley Community Day School in the Los Angeles suburb of Van Nuys, where he counseled gang-hardened teenagers.

And when he thought that his son Joshua, at 7, was old enough to grasp what it meant to be a Marine and why his father would have to go away now and then, he told him, too.

Afterward, Joshua told his friends, his teachers and anyone else who would listen: "My dad's a Marine."

Three days later, on April 9, Good Friday, Eric Ayon was killed at that same intersection. The word is that a homemade bomb—what the military calls an improvised explosive device—exploded. Ayon left the driver's seat for cover and was hit when a second IED blew up.