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.