The pop star's grandfather served in the military and Nick jumped at the chance to honour the men in uniform in the new period film.
"I wanted to do justice to Bruno because he was a real American hero and give respect to our veteran men and women," the "Jealous" singer tells WENN. "A really important moment for me was when I put the costume on. I thought back to pictures of my grandfather, who served in the military, and immediately sent a picture of me in costume to my grandmother."
Nick admits there was one stunt scene in the new film that had him quaking with nerves as his character had to shoot down a Japanese kamikaze pilot.
"All I kept thinking about is, 'I don't want to mess this up', because you only get so many takes," he recalls. "It's such an important moment to set up the stakes for the character and the story that I wanted to get it right."
"With the wet floor and jumping onto the plane and jumping back and seamlessly grabbing the machine gun, there were a lot of moving parts. I try to keep it as real as possible and intense as I can and live in that moment. I do that throughout the whole day, staying in that frame of mind, letting those stakes sit with me, because I want to bring the audience all of the feelings and all of the emotions in the heightened sense of reality in those moments."