"It's such a privilege to be able to do my hobby as a job," Irvine said.
Irvine is not the first star Spielberg has discovered.
"I have a long history of starting young people, or starring young people, in movies," Spielberg said. "That tends to give me more confidence than less confidence when these kids have done so well for me in the past, so it just opens up the possibilities."
Not only is 21-year-old Irvine new to the movie-making world, he's also new to the equestrian world. Before this film, he'd never even ridden a horse, much less tried to bond with one.
But after two months of pre-production training, Jeremy was hooked.
"I didn't think I would actually in real life have that sort of connection, and maybe a week in, I was a sucker for it. It's so difficult not to be," he said. "There is something so human about horses and the way, this is an animal that is immensely powerful, and it could kill you if it wanted to, yet it lets you get on its back and ride it. I find that fascinating."
"War Horse" is rated PG-13.