Harry Styles went swimming in wool to help prepare for Dunkirk
Now, it’s also the basis of jaw-dropping, edge-of-your-seat action film Dunkirk.
“Really, the idea behind the film is suspense and intensity,” said writer/director Christopher Nolan.
While there's death on-screen, Nolan avoided gore. The horror of war is expressed through the young soldier's desperate attempts to escape.
One of them is played by Fionn Whitehead in his first starring role and first time in a movie, period.
“Nothing really properly prepared me until I was on my first day on set and saw these huge warships and planes flying overhead and hundreds of extras dressed in battle gear on the beach,” he said. “That's when it really settled in and I was like, 'oh yeah this is actually happening.’"
It was also the first film for musician Harry Styles, who prepared - in part - by going swimming in a wool coat.
"It was good just to kind of get an idea of how heavy you were going to be while doing that stuff and I think helped to prepare you rather than going in the first day and being like, 'oh this is quite heavy,’” Styles said.
Much of the movie was shot on the same beach where the real evacuations took place, in similar inclement weather. Nolan also employed some of the original “Dunkirk little boats” that were used during the rescue.
"It was sweet seeing all of them,” said actor Mark Rylance. “They were really funky little boats, odd ones. And ours was a 1930's boat."
The production also used authentic RAF Spitfires for the air battle scenes, and attached IMAX cameras to the wings for point-of-view shots.
In fact, the entire movie was shot on large format film - a rare combo of IMAX and 70mm photography. Nolan hopes audiences will seek out theaters that show the film in 70mm.
"They're seeing the best possible presentation of the story,” he said. “It gives you a sort of emotional, immersive relationship with the events you're seeing."
Travel and accommodation provided by Warner Bros.