The First World War starts with literally horses and carriages and ends with tanks. So it’s the moment where modern war, you could argue, begins. From the very beginning I felt this movie should be told in real time. Every step of the journey, breathing every breath with these men felt integral. And there is no better way to telling this story than with one continuous shot.Three…two…oneGo! Go!From the first moment I talked to Sam about the idea as a one-shot movie, I knew it was going to be really immersive. It’s meant to make you feel that you are in the trenches with these characters. The film in itself is a slice of time. These two young men get sent on a mission to deliver a message to stop an attack.Action!So they’ve got to cross into enemy territory on a race against time to deliver a message that will save 1,600 lives. And the camera never ever comes away from the two characters. There’s always that sort of “get out of jail” card that you have with a movie “Well, you know, we might be able to cut around this or we might take that scene out.” That’s not possible on this film. The dance of the camera and the mechanics all have to be in sync with what the actor is doing when you achieve that it’s really beautiful and exhilarating. Sometimes you have a camera being carried by an operator hooked onto a wire and the wire carries it across more land and it’s unhooked again that operator runs with it then steps onto a small jeep which carries him another 400 yards and he steps off it again and goes around the corner.Let’s go back to one.This film does not take place in a series of interiors. This is endless exteriors. No location ever repeats, so you’re constantly moving through landscapes. Being such an exterior movie, we’re very dependent on the light and the weather. And we kind of realized, well for a start you can’t really light it.Action!Because, you know if you were running down a trench and turning around 360 degrees there’s no way to put a light anywhere. And because we were shooting in story order we had to shoot in cloud to get the continuity from scene to scene. So some mornings the sun would be out and we couldn’t shoot. So, we would rehearse.And we’re rehearsing.And then we’d be waiting around, everyone with their eyes up in the sky, trying to see how long it would take for the sun to move behind the cloud. And as soon as it comes over you’ve got this five-minute window. Everyone would be like, “Come on! Go, go, go.”Go! Go! Go!So you are also in the lap of the gods. It was like a piece of theater every take. Once it starts it can’t stop. If something goes wrong you just have to keep going. Until you actually see it on a screen you don’t really realize how immersive it is and how that technique kind of draws you into it. For me, engagement is very important. And that is behind the way in which we decided to shoot this film. I wanted people to understand how difficult it was for these men. And the nature of that is behind everything.