Some of these soldiers had fought their way from Al-Basrah to Baghdad two years ago. Others took part in the urban battle at Al-Fallujah in November.
Now they are undergoing the transition back to domestic life -- hugging their families, paying electricity bills on time, and going to backyard parties in their neighborhoods.
But many are still haunted by the memories of their combat experience.
Many U.S. troops agree that one of their most disturbing memories is of dogs eating human corpses. Others say they will never forget the smell, the suffering of women and children, and the loss of their own friends in battle.
Marine Private Nate Barbosa says returning home has been difficult:
"Coming back, there are some adjustments," he says. "It takes anywhere from 30 days to six months to adjust mentally [just to] not get jumpy every time you hear a loud noise. Things like that."
A recent study published in the “New England Journal of Medicine” found that nearly 17 percent of all U.S. soldiers who took part in the 2003 invasion of Iraq report combat-related mental illnesses. There has been a notable increase in the number of broken marriages, car accidents, fights, and alcohol or drug abuse.
Like many returning soldiers, Marine Private Thomas Barnard admits sometimes feeling uncontrollable bouts of anger:
"I had a problem with my temper when I first got back," he says.
To help deal with combat stress, U.S. military scientists are working on a new form of treatment that uses "virtual reality" technology. Veterans wear video goggles and earphones to immerse themselves in a combat simulator. They control what they see by turning their head and acting out what they would do in a real combat situation.
To take the soldiers back to the frontlines, the earphones blast the sounds of U.S. combat helicopters flying overhead along with the sound of mortar explosions and incoming sniper fire.
In one section of the simulation, a white pickup truck with Iraqi fighters bursts into flames, while another pickup truck charges straight towards the veteran wearing the goggles.
Jesse Patacsil spent seven months in Iraq and is among a group of soldiers testing the system at the Naval Medical Center in San Diego:
"When I don [eds. wear] the goggles and I hear the explosions, basically, it brings me back to like, 'Where's the casualty?' That's basically what happened, what I had in mind. That's why I'm looking around and running around and walking towards the action, it's to make sure that there is anyone that needs help. That's basically what my feelings were when I was over there," Patacsil says.
As Patacsil goes through the virtual-combat experience, therapists use biofeedback sensors, heartbeat monitors, and other equipment to try to pinpoint the events that raise his anxiety.
Doctor James Spira, a staff psychologist at the Naval Medical Center, says such information can help veterans gain better mental control over situations that cause post-traumatic stress disorder:
"The virtual reality environment is clearly not the same thing as being there. And we don't want it to be the same as being there. We want it to be semi-realistic. We want it to be enough to trigger the thoughts and feelings so they can control those," says Spira.
During the next few months, the military's virtual-reality program will undergo fine tuning. Part of that will be done at the University of Southern California's Institute for Creative Technologies.
Jarrell Pair, a software designer at the Los Angeles-based research center, notes that work is now underway to improve the simulation of sights, sounds, and even smells:
"We do not want to re-traumatize the patient," Pair says. "And that's one nice thing about using interactive virtual-reality technologies. We can tightly control that environment. We can change the volume of the sound, the types of sounds. We can change the time of day. We can change the city from a being a nice peaceful area to something that may be violent. Or anything in between. We hope to really get to the point where we can recreate particular instances that traumatized the patient -- and reintroduce those to allow the person to try and figure out new ways to deal with them."
Skip Rizzo is an assistant professor at the University of Southern California who is involved with the virtual-reality study:
"I'm hoping that this effort will be the start of a larger effort and recognition that if you're going to put people in harm’s way and spend a lot of money and resources on training them to be effective in the battlefield, that a good amount of care and attention is put into helping these folks out when they come back," he says.
Funding for the virtual-reality program during the next three years is reportedly about four million dollars.
It is just one of several options the U.S. military is considering as a pro-active approach to a problem seen after the Vietnam conflict -- the sight of thousands of dysfunctional veterans alienated and alone.