What does '12 Strong' actor Rob Riggle know about the war in Afghanistan? A lot. He was one of the first guys there.

After five years of false starts, Hollywood finally got around last year to making a movie about a small detachment of U.S. Special Forces who entered Afghanistan a month after 9/11 to help capture the Taliban stronghold of Mazar-i-Sharif.

It's called 12 Strong and is based on Doug Stanton's book  The Horse Soldiers, the nickname of the Army's Fifth Special Forces unit, which  rode on horseback with Afghan Northern Alliance fighters to win a strategically important early battle.

12 Strong has an asset uncommon to most modern war movies: It costars a Hollywood actor who was actually in Mazar-i-Sharif in the early days of the war. He's Rob Riggle,  best known for his role as a correspondent on The Daily Show, and for supporting roles in dozens of comedies (The Hangover, The Other Guys).

12 Strong has him taking an atypical dramatic role. He also happens to be playing his own commanding officer of the time, Max Bowers.

Riggle served in the Marine Corps before turning to acting and was working on The Daily Show, sharing an office with John Oliver, on 9/11. Riggle — at the time still active in the reserve — immediately got a call to suit up.

"We were the only reserve unit in Manhattan. I was activated that night. My C.O. said put on your utilities and report to ground zero tomorrow. So from Sept. 12th to the 30th, I worked on the rubble piles, moving debris, manning the bucket brigade 12 hours on and 12 hours off."

He said it felt good to be doing something useful.

"My country was just attacked, and I was pissed, to be honest with you," he says.

Riggle volunteered to go on active duty. He was called up before Thanksgiving, and "by Nov. 30th, I was in Afghanistan. So boom, it happened quickly."

He worked as a communications officer on Bowers' staff, and was stationed in Mazar-i-Sharif,  arriving shortly after a prison revolt enacted by some of the Taliban captured in the fighting depicted in 12 Strong.

Riggle got to know some of the Special Forces soldiers, who are played by Chris Hemsworth, Michael Shannon, and Michael Peña in the film. He met with Afghan Gen. Abdul Rashid Dostum, Northern Alliance leader and a key character in the film, and now Afghan vice president.

So Riggle knew the story well when he arrived on the set of 12 Strong. In another sense, though, it was new territory for the actor, who's done of lots of comedy but very little drama.

"With comedy, you get feedback right there on the set. You can see the crew trying to stifle a laugh," Riggle said. "In a straight dramatic role, you don't have that. The drive home at night is different. You're thinking: I have no idea if this is working."

Riggle has another dramatic role this year in Midnight Sun, playing the father of a young woman (Bella Thorne) with a rare disease.

He also has a few more comedies in the bag, including Kevin Hart's Night School, due out later this year. He praises Hart's generous nature as an actor.

"Kevin's the star. But if you come up with something funny in a scene with Kevin and it gets a laugh, he's quick to say, 'Let's go with that,' " Riggle said.

For now, he's helping to spread the word about 12 Strong, a movie that has meant a lot to him as an actor, a Marine, and an American.

"In the annals of military history, this is something pretty special, when you think about what [the solders] did with what they had, where they were, in the amount of time that they did it. Calling in airstrikes from seven miles up. Working with Afghans who didn't speak our language, and we didn't speak theirs, but we both spoke Russian so we made it work." Riggle said.

"It good to know you have people who can do things like that, who are prepared for things like that. As you and I are talking right now, people are out there preparing for the next thing. We don't know what that is, but we know they are preparing, and that's why we sleep at night."