Meet the young star of Christopher Nolan's Dunkirk

In May 1940, the Allies faced a dire scenario. The only escape from Hitler’s blitzkrieg for the nearly 400,000 soldiers stranded on the beaches of Dunkirk, France, was across the English Channel. Over the course of eight days, the vast majority of troops were rescued. In the U.K., the evacuation of Dunkirk is considered a pivotal historical moment, and yet most Americans don’t know about it. That’s about to change.

For Dunkirk, Christopher Nolan enlisted Tom Hardy, Kenneth Branagh, Mark Rylance, Cillian Murphy, and even One Direction’s Harry Styles in his cast, but the star is 19-year-old Fionn Whitehead, a London native making his film debut.

“One of the key things you came across, reading first-hand accounts of Dunkirk, was how young and inexperienced these soldier were,” Nolan says. “It felt very important to me, especially for Fionn’s part, to find somebody very new.”

Nolan’s search was extensive and involved several rounds of auditions. Eventually, he found Whitehead, an actor with only Him, a three-part ITV miniseries, to his credits. The part would be an enormous break for anyone, but Whitehead had to keep the casting a secret, even to his Him costars. “I felt so guilty,” Whitehead says. “Everyone was commiserating with me. ‘Never mind, mate. You’ll get the next one, aye? Not to worry.'”

Whitehead, who plays a British private named Tommy, arrived in Dunkirk weeks before filming to prepare physically for the demands of the role, wading into the frigid water as practice. “I did a lot of swimming in a water-sodden wool uniform, hobnail boots, and with guns,” Whitehead says. “It was hard work, but I really enjoyed it. What’s life without a bit of a challenge?”

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The goal for Whitehead was not to transform himself into a superhero, but just to make sure that he could get through the physical rigors expected of a World War II soldier.

“The stunt team put me through my paces and getting my physically in shape just to be able to do the shots that were going to be demanded of me, to be honest,” Whitehead says. “They didn’t want me to be some super human, just in order to be able to do the things that were required and to not get sick and not be too tired to get a bit more in shape because I was very scrawny when I went for the role.”

Dunkirk arrives in theaters July 21. See a new photo from the film above, and its trailer below.