"It's stuff you hear about in boot camp, about World War II and Tarawa Marines who won the Medal of Honor," said Lance Cpl. Rob Rogers, 22, of Tallahassee, Fla., one of Peralta's mates in 1st Platoon, Alpha Company, 1st Battalion, 3rd Marine Regiment.

Peralta, 25, as platoon scout, wasn't even assigned to the assault team that entered the insurgent safe house in northern Fallujah where he died, fellow Marines said. Despite a billet that would have allowed him to avoid such dangerous duty, he regularly asked squad leaders if he could join their assault teams, they said.

One of the first Marines to enter the house, Peralta was wounded in the face by rifle fire from a room near the entry door, said Lance Cpl. Adam Morrison, 20, of Tacoma, Wash., who was in the house when Peralta was first wounded.

Peralta fell to the floor near the breach, Morrison said. Moments later, an insurgent rolled a fragmentation grenade into the area where Peralta and the other Marines were seeking cover.

As Morrison and another Marine scrambled to escape the blast, pounding against a locked door, Peralta grabbed the grenade and cradled it into his body, Morrison said. Although one Marine was badly wounded by shrapnel from the blast, the Marines said they believe more lives would have been lost if not for Peralta's selfless act.

"He saved half my fire team," said Cpl. Brannon Dyer, 27, of Blairsville, Ga.

The Marines said such a final act would be perfectly in character for Peralta, a Mexico native who lived in San Diego and gained U.S. citizenship after joining the Marines.

"He'd stand up for his Marines to an insane point," said Rogers.

Rogers and others remembered Peralta as a squared-away Marine, so meticulous about uniform standards that he sent his camouflage uniform to be pressed while training in Kuwait before entering Iraq. But mostly they remembered acts of selflessness: offering career advice, giving a buddy a ride home from the bar, teaching salsa dance steps in the barracks.

While Alpha Company was still gathering information, and a formal finding on Peralta's death is likely months away, not a single Marine in Alpha Company doubted the account of Peralta's act of sacrifice.