Some find their experiences too much to bear. There were 115 military suicides last year, and 93 through just August of this year.
The biggest obstacle to getting those numbers down may be the military culture itself, reports CBS News correspondent Kimberly Dozier.
First Sergeant Jeff McKinney was a model soldier, a newlywed, and a new father.
Now, his family says, he's a casualty of war. Two wars really: the war in Iraq, where he served honorably, and the war within the military over how to deal with post-traumatic stress disorder.
On July 11, 2007, McKinney, serving on his second tour, killed himself in front of his men. He had endured months of sleeplessness, nightmares and guilt over losing so many of the soldiers he commanded.
"I think he felt like he couldn't send one more broken body home, one more dead person home," Jeff McKinney's father, Charles McKinney, said.
McKinney's personal battle mirrors the war within the U.S. Army, between those who call combat stress a killer, and those who call it an excuse.
In McKinney's case, there had been troubling signs, but he hadn't been taking the medication given to help him cope -- and his captain feared taking him off duty would destroy his career.
Commanders like First Sergeant McKinney are often the hardest to convince they need help.
"We've got a rough and tough, sort of macho culture that says none of that soft squishy touchy feely stuff," said Brigadeer General Loree Sutton, director of the military's Center for Psychological Health and Traumatic Brain Injury. "Well, we need to bring the brain out of what has been a black box."
But that's fighting Army tradition.
Commanders at one army base posted a fake "Hurt Feelings Report" -- portraying a crying cartoon face -- to mock soldiers seeking help for combat stress. Selections on the form included: "I am a crybaby," "I want my mommy" and "All of the above." It was tacked on the barracks bulletin board, next to the sign-up sheet, for the mental health clinic.
Sutton says the military's challenge is to teach soldiers - and commanders - that the nightmares or flashbacks aren't signs of weakness.
"It's about starting a different dialogue, giving folks permission to talk," she said.
The military is testing promising pilot programs.
Instructor and former Army ranger Steve Robinson, who works for the organization OneFreedom.org says it's about training the brain to cope with traumatic memories: "Teaching soldiers skills like visualization, event resolution, breath work, quiet time so they can process what happened."
But for First Sergeant McKinney, there were no such tools to cope. His wife says she knows what she'll tell her son.
"He needed help and nobody helped him," Chrissy McKinney said. "And that's the reason why he died."
But, she said, "He died a hero."