From IMDB:

Allied soldiers from Belgium, the British Empire and France are surrounded by the German Army, and evacuated during a fierce battle in World War II.

British Airways offered this film along with subtitles.

Dunkirk is famous for the heroism of the small British boats that came to the rescue of the surrounded allied soldiers. In this regard I hope you can someday read the beautiful short story “The Snow Goose”.

HOWEVER, this particular film, far from any romanticizing, shows all the horror and death associated with the Dunkirk rescue. There were also large rescue ships. But several ships and passengers perished. Sometimes a sinking ship left a cover of oil on the water which then caught fire and burned soldiers to death. All in all, the scenes are difficult to watch.

As a human-interest note in the film, one British small boat owner and his sons are featured. Along the way they rescue a shell-shocked soldier, further showing the horror of war.

Also featured are the British pilots who tried to battle the German planes that came to bomb the marooned soldiers.

Inspiring, terrifying, but worth the watch.