On his first night in the city, Sgt. Aristotel Barbosa slept uneasily on the floor near the door of a vacant house that his Marine unit had taken over. A squad leader in the 3rd Battalion, 1st Marines, Barbosa had been prepared for the worst when U.S. and Iraqi forces began storming into Fallujah on Monday night.

Instead, the slight 26-year-old from Southern California was surprised to find fighters in the city putting up little resistance. By Thursday night, U.S. troops had taken control of the northern half of Fallujah, which lies about 35 miles west of Baghdad, and Barbosa was feeling optimistic about the battle when he woke up Friday. He decided not to shave, figuring things would be over soon enough. "I'm thinking and hoping that it's not that bad," he said, recalling his mood at the time.

But for many Marine and Army units, the battle for Fallujah was only beginning.

Barbosa and his squad set off on foot at 7:40 a.m. Friday following a slow-moving column of Marine infantrymen heading east just below the main highway that divides northern and southern Fallujah.

As he trudged through the desolate, rubble-filled streets, Barbosa said he remembered thinking how bad the city looked, worse than he had imagined. "Basically every house has a hole through it," he said.

Then the unease hit again. "All the squad leaders and myself, we knew when we got to the south we were going to get pounded."

As they began the turn south, gunfire burst from a mosque in front of them. Another platoon began shooting back, and Barbosa led his squad around to the side. "The whole company kept pushing, and we started getting hit from the other side of the street," he said.

Gunfire tore through an aluminum gate when the squad passed a house. Barbosa said he felt a sting in his right bicep. He had been shot. Two other members of his squad were wounded within minutes of each other, including Lance Cpl. Matthew Vetor, 21, who was hit in the lower back just under his flak jacket.

"It was like a whole block of insurgents," Barbosa said Saturday while recuperating with Vetor in a Navy field hospital at a military outpost near the city. "They started throwing grenades at us. It was like a shock. I couldn't believe I got hurt. I went two more blocks. I couldn't believe it."

It was 12:30 p.m.

Barbosa found his gunnery sergeant, who ordered him back to a medical vehicle that the Marines call the "track" or the "big bus."

"I thought they were going to get me out of there," Barbosa said. "But we kept pushing. I could still fight. I had to go leftie, but I was still fighting."

Meanwhile, Vetor was feeling the blood trickling down his face from a shrapnel wound. "I thought it was just my face," he said, until he felt the pain in his back. "I started to run," he recalled. "But it was difficult. We just kept making our way to the track. The hatch opened, and I jumped in. I gave out all my ammo. They took my flak and Kevlar. The doc had me lay down in the center and pulled out some shrapnel."

From inside the medical vehicle, Vetor said he could hear the fighting. "I'm there without my flak or helmet. You hear the shooting going on," he said. He felt afraid.

The column of Marines kept moving, with Vetor riding in the medical vehicle and Barbosa continuing on foot. Barbosa said the unit had to keep moving so the air power could come in behind them and clear the houses the insurgents were shooting from.

"There wasn't one house that didn't have weapons," Barbosa said. Every house had at last one rocket-propelled grenade and a couple of hand grenades, he said.

"They were very prepared," Vetor said, as he and Barbosa sat next to each other on a green cot in the field hospital's overflow medical ward.

"Like they were waiting for us," Barbosa said. "They were waiting for us."

As he walked along the street, Barbosa said, he had to step gingerly around improvised explosive devices that had been strung together.

About an hour later, Barbosa and Vetor found themselves in a large, vacant residence not far from the scene of the gun battle. The Iraqi special forces assigned to their unit found some rice and vegetables and made lunch. The Marines were nursing their wounds and eating hot chow when an explosion occurred nearby, shattering the windows and flicking shards of glass into the food.

It was 1:45 p.m.

Five hours later, Barbosa and Vetor made it out of the city to a staging area. They were taken to the military hospital, where on Saturday afternoon they were watching a movie and waiting to be transferred back to their unit.

Barbosa, twirling a cigarette lighter in his hand, planned to get back into the fight. Vetor, who said he could squeeze shrapnel out of his facial wounds, would not be able to return just yet.

"You know it could happen to you, but you really don't think it will be you," Vetor said, looking at the TV screen. "I'm just glad I was part of it. I was glad I got to fight with these guys. It had to be done. We were really fighting. We were doing great. It doesn't stop us. We'll keep going."

Barbosa said that even when the offensive was officially declared over, his squad planned to remain in the city to keep the peace. He expected things might get worse then, particularly if the artillery and mechanized infantry move out.

"We're not going to kill everyone, and they're not all going to surrender," he said. "I know that a lot of them are left. They'll wait for things to calm down, and they'll come back. They always do."

Barbosa said he would, too, and took a swig of juice from the box in his hand.

A Marine takes aim under fire in western Fallujah. About 80 percent of the city was reportedly under U.S. control.A street in western Fallujah lay deserted and rubble-strewn in the wake of fighting between Marines and insurgents. About 80 percent of the city was reportedly under U.S. control.