In past wars, it was called combat stress, battle fatigue or shell shock.
Now it's called post-traumatic stress disorder -- and with violence in Iraq so widespread and the tours of duty so long, there is a growing concern that veterans of that conflict are suffering in far greater numbers than casualty figures are able to accurately reflect.
The Army has expanded its efforts to help soldiers, putting more mental health teams in Iraq and on call at bases in the United States than it has ever done before.
It has also extended measures to deal with PTSD from the moments after a traumatic event, to when troops come home and after. Some soldiers are screened months after they arrive home.
"It's a disorder that evolves over time," said Robert Ursano, chief psychiatrist at the military's own medical school in Bethesda, Md.
"We know that there's both acute PTSD in which people recover in three to six months and there can be chronic PTSD that can go on for decades and decades and decades."
What's clear to mental health professionals now is that PTSD can't be solved by simply going home -- as many soldiers might like to believe.
"A lot of them feel if I get back to my spouse, if I get back to my secure environment, this will all go away," said Col. Michael Bridgewater, a clinical psychologist at Ft. Polk, La. "Well, it doesn't go away."
For any soldier, finding ways to deal with the psychological stresses of combat -- as they are happening -- is a matter of survival.
"The fact that you're going to confront the fact that you're going to kill another human being -- that is traumatic just as much as the stress of being killed," said Sgt. Steve Jenkins.
But in the moments after a rough incident, soldiers also often find the first line of defense in relieving the extreme tensions of combat is the simple act of a soldier talking to his buddy.
Military psychologists now believe some of the most important steps in countering PTSD must be taken in this time. The soldiers must be able to "process" and defuse the stress in the middle of an ongoing war.
"You have one of those days -- we call them bad patrols," said Sgt. First Class Joseph Bosely.
"The guys come back and everybody starts talking to everybody else and everything comes out in the open."
But that is not always enough. Sometimes it's necessary to remove a soldier who is struggling from his unit.
"We had one soldier with battle fatigue and we pulled him out of the line for almost two weeks," said Capt. Dale Murray. "He came back, it was like he was never gone. His mind was there, his body was there and he was performing just like we needed him to."
Murray can tell when the tension of war has eaten away at a soldier. He recounted the signs: "Withdrawing, talking again and again about the episode, saying things like "I don't know if I can do that again."
When the troops come home, they are screened. Every soldier must answer a detailed questionnaire and meet one-on-one with a mental health technician.
They're urged to seek help if they have trouble with nightmares or start drinking excessively. They're also asked to keep an eye on their buddies. And they receive advice on re-establishing intimate and sexual relationships.
In addition, mental health technicians at Ft Polk, La., give a second full mental health screening three months after soldiers return home.
Symptoms of PTSD often take months to become obvious. The second time around, doctors were finding twice the number of soldiers in need of help than they did after the first screening.
Though many soldiers are still reluctant to seek therapy or medication, attitudes within the Army about getting help have changed dramatically.
"When I first came to the army in 1988, I was 18 and the medical profession -- you just didn't go," said Bosely. "If you did, you were less of a soldier."
Nowadays, if a soldier has a problem, "It's not 'Hey do you want to go to the medics?' It's 'Come with me,' " he said.
Accordingly, there has also been a much broader acceptance of using a family of drugs commonly prescribed for depression, anxiety and insomnia to deal with PTSD. These medications are prescribed for soldiers who have returned home as well as those who are struggling during their tours in Iraq.
Sgt. John Newport, who says he was traumatized when he saw a young Iraqi girl crushed to death by a truck, is now taking Zoloft. "It's actually made it that I'm not so jumpy," he said.
Harriet Barton, who was wounded in a landmine explosion and then caught in an ambush, was prescribed Paxil. "I don't have those uncontrollable crying urges anymore," she said.
However, some have also learned to deal with the stress of combat in more personal ways.
Sgt. Brett Bingham, who spent a year in Iraq, keeps a journal as a way of coping with the insanity of his daily life. He says the journal allowed him to "download every single incident that happened and I could kind of forget it."
As a combat medic treating hundreds of American soldiers and Iraqis, he saw terrible things. For example, in one passage, he described seeing an enemy fighter after he had been shot.
"The left side of his skull had been blown off and all that was visible was his brain. I do not know what to do. I have seen so much blood and death. It's enough for a lifetime."
He also wrote dark poetry to calm his nerves.
As death comes like the shadows creep/ We watch children suffer as parents weep/We came to give a better life/ We leave in the midst of turmoil and strife.
Many soldiers are able to come home, struggle briefly with the adjustment, and then move on.
But thousands -- perhaps tens of thousands -- will be crippled for months or years by traumatic stress from the violence they experienced. They have left Iraq, but for some, the war goes on in their heads.
"I don't think you can go into a combat zone and return the same," said Stanley Arnold, an Army chaplain.
"The horrors of war, the ethical dilemma in being sent on behalf of your nation, to protect it. The struggle, our very nature is against killing someone else. And we have to, as soldiers, face that ethical dilemma."