So far, more than 2,100 soldiers have been injured – 1,500 since the president declared the end of major combat. Correspondent Susan Spencer has the story of three of those young men - Robert Acosta, Alan Lewis and Dave Pettigrew - whose lives were torn by war and rescued from the battlefield.
"Growing up, I was kind of in a lot of trouble, and messing around a lot. I would always party," says Robert Acosta, 20, from Southern California. "I don't know where I'd be if I didn't join the Army. The Army did a lot for me. I'd probably be in jail or maybe even dead."
"He wasn't the worst kid ever, but, I mean, it gave him a purpose," says Acosta's mother, Patricia. "It made him proud of himself. He was proud of what he did. He was proud of the way his life was, and he loved it."
Alan Lewis, 23, grew up in Chicago's projects: "I always knew I was gonna serve my country and do my share. Growing up in that environment, it lets you see things. Like a drug addict, you may see an alcoholic, you may see a person and you might say, 'Well, he's made this mistake in his life.' I don't want to make that same mistake."
"He's always been, like, a leader, you know, never a follower," says Lewis' mother, Audrey. "I knew whatever he did, he was gonna be good at it. Alan's thing is, be the best at whatever you do."
Texan David Pettigrew, 26, met his wife Ann while stationed at Fort Carson in Colorado. When they married two years ago, war seemed only a vague possibility. "My wife swore she would never marry a military person, because her dad was military and bounced around all the time," says Pettigrew.
"Everything was fine. The country was at peace. I didn't see this [war]coming at all," adds Pettigrew's wife, Ann.
When the war began in March, Lewis' unit, part of the Third Infantry, led the way. At last, Lewis said he realized his dream of becoming a real soldier: "When they dropped the ramp and we dismounted, I just felt a surge of adrenaline pumping through me, and it was no fear whatsoever."
Acosta, a munitions specialist with the 1st Armored Division, also felt he was ready to go. He showed Spencer a photo of his mother's visit to Germany before he was deployed to Iraq.
Pettigrew, a gunner with the Fourth Infantry, was soon on his way to Kuwait. "There was a little bit of excitement there, 'Hey, we finally get to do our jobs,'" recalls Pettigrew. "All you do is train for the eventuality of a war with someone."
But his wife says she dreaded what might lie ahead: "I wrote him almost every day, and what I said was that he had to come home. He could be missing parts, he could be out of his mind, he could be crazy and deranged, but he had to come home."
In mid-April, Baghdad fell and a second wave of American troops entered the country – including Pettigrew and Acosta.
"The drive from Kuwait to Baghdad, there was some towns where the people loved us. They'd cry and say how much they loved us and thank you and what not," recalls Acosta. "And then other towns would throw rocks at us, and you're like, 'Just down the road they loved us, what?'"
"There'd be shootings every night. You'd see tracers flying over. Every once in a while you'd hear an explosion," says Pettigrew. "But no one ever actually attacked us. We never actually got in a real firefight."
At home, Patricia Acosta kept anxious watch on the news from Iraq. "You get up in the morning. You watch the news and see. And if it said soldier injured or killed, I would pray, 'Please don't let it be my son,'" says Patricia. "And if nobody called or knocked by the end of the day, it would be a good day, and I would feel bad for the other families."
On July 13, on his day off, Acosta donned his body armor and hopped in a Humvee with a buddy. They were going on a quick trip to get some ice.
"We were driving down and there really weren't any American vehicles, so that made me nervous. So I told him, 'I don't like this, let's go back,' and as soon as we made a U-turn, a grenade just flew into my window and it landed between me and my buddy," recalls Acosta.
"I grabbed it and everything but when I went to throw it out, it fell between my legs. I reached down to grab it again. I had it in my hand. I was gonna throw it out and it went off in my hand."
Three days later, Lewis was on routine patrol with his lieutenant when their truck hit a landmine. "It just feels like you're sinking into your seat and at the same time you're rising out of your seat — and it feels like your soul jumps out of you," says Lewis.
"I realize that I'm on the ground and it's like, all right, I need to get out of here and move away from here because I could smell the explosion. I started crawling away from there and then I realize I'm not crawling too fast."
It was just a regular night patrol south of Kirkuk when Pettigrew got into trouble. Three months to the day he'd arrived in Iraq, an armor-piercing, rocket-propelled grenade hit Pettigrew's Bradley.
"I knew I was badly hurt. I've got to get myself out of this vehicle if there's any chance of these guys getting me out," recalls Pettigrew.
"So I pulled myself out and laid on top of the tow launcher. I blacked out for a little bit and woke up on the ground. They were putting a tourniquet on my leg. You put a tourniquet on something because it's bleeding so bad they're going to die from it."
In the blink of an eye, the lives of three young Americans were changed forever.
It all happened in just one second, but it was a moment Robert Acosta recalls with complete clarity: "I was totally conscious. I saw everything. I mean, I saw my hand gone."
He also realizes that he owes his life to the soldier who was riding with him: "He picked me up and he carried me … I owe him everything."
Dave Pettigrew also has no doubt that his life was saved by those who were with him at the time of the attack. "Great big huge boom," he recalls. "Woke up on the ground and my guys were putting tourniquets on me."
Looking at the wreck of his Humvee, it's amazing that Alan Lewis got out alive. "I just thought my arm was just messed up. I didn't even realize my legs were gone," says Lewis. "I started yelling out for help and my team leader comes up and he picks me up and then carries me to our Humvee. From there, they took me to a helicopter."