A new trailer for Christopher Nolan's World War II drama "Dunkirk" is here and it looks incredibly tense, with soldiers stranded on the beach and facing overwhelming firepower -- and Harry Styles nearly drowning! (If Nolan kills off the former One Direction star, we will never hear the end of it!)

"Dunkirk" tells the real-life story of how civilians rushed in to save 400,000 stranded Allied soldiers during one of the fiercest battles of the war.

In voiceover we hear (we assume) Kenneth Branagh (who plays a grim-faced naval commander) say: "What has happened is a colossal military disaster... we shall go on to the end. We shall never surrender."

We also get good glimpses of "Bridge of Spies" Oscar winner Mark Rylance, who's one of the civilians who pilot their boats into the war zone to rescue stranded troops, and Cillian Murphy as one of the sailors he rescues, who then refuses to go back to the battle lines.

We get much briefer a look at Tom Hardy as a pilot and James D'Arcy as an officer who doubts the use of the civilian forces.

Here's the full trailer for the movie, which opens July 21.