"I struggled to think of days when there wasn't gunfire or explosions or attacks," he told 48 Hours correspondent Erin Moriarty. "This is how things are going to play out and this is what you've got to do to survive."
An e-mail he wrote to his family appears in the book "Operation Homecoming," along with other writings by other soldiers, sailors, airmen and marines compiled by the National Endowment for the Arts. McCary's heart-felt essay is called "To the Fallen."
"Dear all. We are dying," he writes. "Not in some philosophical, chronological, the-end-comes-for-all-of-us-sooner-or-late sense. Just dying."
"I had to write home about what — what it was like to have known someone and worked with someone one day and to quite literally lose them the next," he said.
As long as there have been wars, there have been writers struggling to make sense of them. For McCary, Iraq was "a nightmarish wonderland."
"Because it's really bizarre and it's exciting and intriguing and fascinating and horrifying all at the same time," he said. "You're consumed by it."
"We thought we had turned the tide, turned the corner, but they are still here," he wrote in his essay. "They still strive for our demise. No one looks to wake up in the morning saying, 'I hope killing a bunch of Iraqis goes well today.'"
McCary never imagined that his words, which began as letters home, would become part of a book and now a documentary about the latest chapter in American war writing.
In the documentary, to air Monday night on PBS, the stories, essays and poems are read by actors and brought to life using video, photographs and animation.
McCary is a Vassar College graduate, fluent in Arabic, who wanted to serve his country as an interpreter in Iraq.
"So I joined up with the idea of going off to fight terrorists," he said.
But he soon found himself at war with himself.
"No experience from my childhood or my professional experience as a young adult prepared me for what I was going to see," McCary said. "I mean, you're asked to do very absurd things, like seek out and possibly kill someone, for reasons that you've been told and that you honestly believe are the right reasons. But when it comes down to actually committing the act, I think it's a face-to-face, coming to terms with a very stark and harsh and non-negotiable reality."
Two Army veterans, who also appear in the documentary, novelist James Salter and Pulitzer Prize-winning poet Yusef Komunyakaa, know much about war and even more about war writing.
"We're hoping to preserve something and explain something," Salter said. "And you have to do that. It's the human impulse to do that, to say 'This is what happened.'"
"I think of all war writing as anti-war," Komunyakaa said. "And that's what interests me: The fact that one has captured the spirit of that intense, brutal moment, and try to make some sense out of it."
Some writers try to make sense out of war in a lighthearted way. In the documentary, an Army staff sergeant offers his own take on desert living conditions, complete with detailed instructions:
"Go to your vacuum, open the canister and pour it all over you, your bed, clothing, and your personal effect," he says. "Now roll in it until it's in your eyes, nose, ears, hair and, well, you get the picture."
Salter says there is humor in war. There is even Shakespeare.
"He has jokes and tragedy mixed, slapstick and bloodiness," Salter said.
"Sometimes they're joking because of fear, I think ... lighten things up, which may be impossible," Komunyakaa said.
Marine Lt. Colonel Mike Strobl kept the details of his mission in a journal. His job was to escort the body of a young marine home to his family in Wyoming. Nineteen-year-old Lance Corporal Chance Phelps was killed in an ambush.
"I thought it would be difficult," Strobl said. "But it was definitely more emotional. I was surprised how emotionally attached I became to him along the way. And I really felt a sense of loss when the mission was over."
"As I had done all week, I came to attention and executed a low, ceremonial salute as Chance was being transferred from one mode of transport to another," he writes.
Sections of Strobl's journal are read in the documentary by actor Robert Duvall.
"Now he was home to stay and I felt at once sad, relieved and useless," Strobl writes. "It had been my honor to take Chance Phelps to his final post. Now he is on the high ground overlooking the town. I miss him."
The documentary and "Operation Homecoming" reminds us once again that writing about war won't end it. But it just may help some of us survive it.