As per ThePlaylist "The film is inspired by Operation Dynamo, the near-miraculous evacuation of the British Expeditionary Force (BEF) and other Allied troops from the French seaport of Dunkirk, which took place from May-June of 1940. Hoyte van Hoytema ("Interstellar") is lensing the picture, with Hans Zimmer providing the score."
Nolan's last film Interstellar had its fair share of haters, but it really grew on me and now I unequivocally believe it is one of his very best films. It'll be interesting to see what he does in a genre that stems far away from Sci-Fi, in fact the last time Nolan didn't deal with Fantasy, Superhero or Science Fiction genres you'd probably have to go back to 2002's Insomnia - which was a pretty damn good movie, might I add.