Pop star Harry Styles of One Direction fame has joined the cast of director Christopher Nolan's next film, Dunkirk, which chronicles the British army's historic evacuation of Dunkirk, France during World War II. Oscar winner Mark Rylance, Kenneth Branagh, and Tom Hardy are lined up to play supporting roles in an ensemble to be led by mostly unknowns.

"It is not believed to be a leading role," Deadline claims of Styles' role. In addition to Styles, Dunkirk has also reportedly cast Aneurin Barnard and Jack Lowden, who also co-star together in the 2016 TV miniseries adaptation of War & Peace. Barnard's credits include The White Queen and Citadel, and Lowden appeared in last year's '71.

One Direction's Harry Styles and War & Peace co-stars Aneurin Barnard and Jack Lowden cast in Dunkirk.

In addition to the aforementioned cast members, Dunkirk has also cast newcomer Fionn Whitehead. TheWrap claims he will "play one of the two young leads." A relative unknown, Whitehead's most notable role so far was in the ITV three-part drama Him.

Dunkirk will be shot on a combination of IMAX 65mm and 65mm large format film photography. Shooting will begin in May using many of the real locations of the true-life events, which form the background for the story.

Warner Bros. has set Dunkirk for a July 21, 2017 theatrical release on IMAX, 70mm, 35mm and all other screens.