Army Staff Sgt. Ian Newland spotted the enemy grenade inside the Humvee. Almost simultaneously, he saw Spc. Ross McGinnis, 19 — a gunner standing in the turret of the vehicle — lower himself onto it.

"I saw him jam it with his elbow up underneath him," says Newland, who was sitting inches away. "He pressed his whole body with his back (armor) plate to smother it up against the radios."

The heat and flash of an explosion followed, and McGinnis was killed. Hours later, after surgery for shrapnel wounds, Newland realized the enormity of what happened: McGinnis had sacrificed himself to save four other soldiers in the Humvee on Dec. 4. "Why he did it? Because we were his brothers. He loved us," Newland says.

Since the Iraq war began, at least five Americans — two soldiers; two Marines, including one stationed at Kane'ohe; and a Navy SEAL — are believed to have thrown themselves on grenades to save comrades. Each time, the service member died from massive wounds.

Heroic acts mark every war; among the most remarkable involve self-sacrifice. "What a decision that is," says Frank Farley, a Temple University psychologist who studies bravery. "I can't think of anything more profound in human nature."

Survivors, while deeply grateful for their lives, find the aftermath complicated. According to interviews with a dozen surviving soldiers, sailors and Marines, there remains an overpowering sense of guilt and an unspoken feeling that they need to be worthy of the sacrifice.

"There's always talk (in the Army) about being the hero," says Newland, 27, now in Schweinfurt, Germany. He has been diagnosed with mild traumatic brain injury from the December blast and post-traumatic stress disorder.

In the military, "everyone always tells their friends, 'I'd take a bullet for you,' " Newland says. "I've read books and seen plenty of movies about it. But to actually live through a situation like that, have someone do that, is just — there's nothing else more courageous that a person can do in their entire life. ... So basically, I try not to live my life in vain for what he's done."

Such heroic acts almost always lead to a military review for the Medal of Honor, the highest U.S. military decoration.

The medal was awarded posthumously in the first instance of such heroism in Iraq to Marine Cpl. Jason Dunham, 22, of Scio, N.Y. He covered a grenade with his helmet on April 14, 2004, and saved the lives of two Marines in western Iraq. Dunham died eight days later.

A HEAVY BURDEN

Anyone who wraps himself around an explosive charge cannot block all of its destructive power.

Survivors caught nearby describe intense heat, a shattering pressure wave, dazed awareness, ears ringing or even burst eardrums and a world around them that sounds for several seconds as if it's underwater. Then there's the blood, from muscles, nerves or arteries slashed by shrapnel.

That's just the physical harm.

Emotional damage surfaces later when a survivor tries to square his life with his friend's death, says Navy Lt. Cmdr. Shannon Johnson, who counsels frontline combat soldiers in Baghdad.

"The guilt that those left behind have is sometimes compounded by a sense of unworthiness," she says. "They cannot accept that their lives were worth more than the life of their loved comrade. They are left with the heavy burden of trying to measure up to the great sacrifice so that they could live on. For some, the burden is too much."

On the battlefield, the military tries to provide counseling for survivors whenever lives are lost.

At home, therapists with the Department of Veterans Affairs say survivor's guilt is among the common issues soldiers and Marines bring home from war.

"Being saved by someone from heroics could lead to a sort of (emotional crisis)," says Ira Katz, head of mental health for the VA. " 'He died for me. I really have to prove myself worthy.' And that's probably a very natural response."

Last September, Petty Officer Michael Monsoor, 25, of Garden Grove, Calif., fell on a grenade that landed on a rooftop in Ramadi, where he and two other Navy SEALs were stationed as part of a sniper team. Monsoor saved the lives of the other two.

"You think about him everyday. And everything pretty much revolves around what he did," says a 29-year-old Navy lieutenant with the SEALs, married and the father of one. He declined to be identified as a matter of department policy. "You'd like to tell yourself that you'd do what Mikey did. But until you're faced with that situation, you really don't know."

Marine Sgt. Nicholas Jones still questions his own worth after a nearly identical experience two years before in Fallujah.

Jones entered a house defended by insurgents when his best friend, Sgt. Rafael Peralta, a Kane'ohe Marine, fell in front of him with a gunshot wound to the neck. Seconds later, an enemy grenade landed near Peralta, who grabbed it and pulled it underneath his chest. The blast killed Peralta immediately. Four other Marines, including Jones, were wounded.

Peralta, 25, was born in Mexico, graduated from high school in San Diego and became a U.S. citizen in 2000, when he joined the Marines. He was a member of the 1st Battalion, 3rd Marine Regiment, which arrived in Iraq just one month before he was killed.

"It's weird to think you get a second chance on life because of someone's unselfishness," says Jones, 24, of Ontario, Calif., who suffered shrapnel wounds in the explosion.

"It almost makes you feel less, you know? Less of a person. It's like: Why did somebody go out and do something so unselfish just so that I could have the rest of my life?"

'SELF-DESTRUCTIVE MODE'

Some survivors have nearly been destroyed in the wake of being saved.

Former Marine Cpl. Kelly Miller, of Eureka, Calif., survived because Dunham, the Medal of Honor winner, fell on that grenade in 2004. As part of Dunham's patrol that day Miller, 24, has agonized endlessly in the intervening years over blame, guilt and whether he should have died, rather than Dunham.

He became introverted and angry, says his mother, Linda Miller. "He went into the self-destructive mode," she says.

Last September after a night of drinking, he flipped his Nissan sports car. He suffered a broken arm and his girlfriend, Kellyn Griffin, was severely injured. Felony driving charges are pending.

Deborah Dunham, mother of Jason Dunham, wrote a letter on Miller's behalf to the court, explaining that "Kelly has been chasing his personal demons since Jason gave him the gift of a second chance of life."

A similar struggle consumed Staff Sgt. Jeffery Gantt.

A member of the Virginia National Guard, Gantt was driving a Humvee on Oct. 26, 2005, when the gunner of the vehicle, Sgt. James "Ski" Witkowski, apparently tried to block a grenade from falling inside the vehicle and died in the blast.

"It's almost like time stops. It's like you're outside of your body and you're looking at what's going on," says Gantt, 37, of Fredericksburg, Va.

Gantt is on medical leave from his civilian job as a corrections officer, and has been diagnosed with PTSD and a mild brain injury. Gantt fights the anger he feels for not having done enough — in his view — to keep Witkowski from sacrificing himself on the grenade.

"I remember one day I asked myself, 'Why are you so mad? Why can't you let this go?' And I could feel my chest tighten and I was so (angry)," Gantt says.

His girlfriend of six years, Sheila Ward, says that having his life spared has changed Gantt completely.

"I don't know anything about him (anymore)," she says.

JUST AN ORDINARY GUY

The families of men who gave their lives also struggle with emotional crosscurrents.

Tom McGinnis felt a surge of different emotions over losing his only son: the overpowering grief, pride over the Medal of Honor nomination and wariness about the heroism hoopla. He knew Ross could have rolled out of the gunner's turret and escaped the blast; he felt guilty for nearly wishing his son had done just that.

McGinnis also understood the potential for survivor's guilt when he buried his son at Arlington National Cemetery early this year. After the ceremony, the elder McGinnis met Newland and two other soldiers saved by his son's heroism, and he consoled them.

"I tried to emphasize to them that they can't continue living thinking they're indebted to Ross for what he did," the father says. "They can't go on for the rest of their lives thinking, 'I'm here because of Ross.' I wouldn't think Ross would want them to feel that way.

"Things just happen."

McGinnis says he does not want his son depicted as larger-than-life. The father says his son loved rebuilding car engines, worked at McDonald's and had a gift for making people laugh. But he was a disinterested student and barely graduated from high school.

"He wasn't exceptional. He was just like you and me," Tom McGinnis says.

"He just made a split-second decision (to fall on the grenade). He did what he thought was right. That doesn't make him extraordinary. He just did an extraordinary thing."