Christopher Nolan's Great War

Nolan, 46, has built a career making smart films that are also blockbusters. His 10th feature, Dunkirk, is the British-American director’s most ambitious yet. He spoke to TIME about how and why he made this film now

- Eliza Berman

Over the past decade, you’ve made movies that take place in the DC Comics universe, within the human subconscious and out in space. Why come back to earth, to history?

Dunkirk is one of the great untold stories in modern cinema. Having made a trip on a small boat across the Channel about 25 years ago, the roughness of the water, the sheer physical challenge of making that crossing—but without anyone dropping bombs, without traveling into a war zone—cemented in my mind an extraordinarily high level of admiration for the people who in 1940 just got on those little boats and came over to help the soldiers.

Growing up in Britain, what was your perception of the events at Dunkirk?

In Britain, you grow up with this story. It’s really part of the national DNA. It’s in your bones as a British person. You receive the story first in its more mythic, somewhat oversimplified terms. The more you find out about the reality of the evacuation, the more you find out about the messy historical truth of the thing.

Do you think there’s a particular reason why the story hasn’t been told in film?

Yes, I do. What I realize in retrospect is this is a British film—it has no Americans in it—but it needs the Hollywood studio machine to be able to make something technically on the scale that’s necessary to do this story justice. I’ve always seen Dunkirk as a universal story, something that anybody could relate to. But the reason why it hasn’t been made before is it requires such massive resources.

How did you approach research?