The former One Direction member and his co-star Fionn Whitehead sat down with E!'s Erin Lim to chat about the film.
"I really loved working on this film," Styles gushed about the cast and crew, including director Christopher Nolan. "I really enjoyed the experience, it was good fun."
In his movie debut he plays Alex, a hardened soldier fighting at Dunkirk. However, acting was only half the battle as Styles also had to make a few personal changes in order to play the role.
Styles recounted how he chopped off his locks—remember that now-famous photo he posted to Instagram holding his braid?—to fit the part of a World War II soldier.
He said he didn't "really think" about having to make the change because he was "very excited to be getting to set and being involved and working on [the film]."
He noted that "it kind of went without saying," and joked that having shorter hair for the first time in years also had its perks. "It was a little breezy behind the ears, which was nice," he laughed.
Warner Bros. Pictures
Not to mention, Styles exchanged his hair for a massive role...and a little more.
In fact, both Styles and Whitehead admitted they took a couple mementos from the set to remember the experience. While Whitehead said he snagged a couple dog tags, Styles said he took a costume helmet.
"How did you sneak that out?" Whitehead asked as the actor and musician coyly smiled and cleared his throat to dodge the question.
Dunkirk premieres in theaters on July 21st.