Dunkirk why hasn't Hollywood ever made a Movie its an amazing story of courage?

Between 27th May and 4th June, 1940, a total of 693 ships (39 Destroyers, 36 Minesweepers, 77 trawlers, 26 Yachts and a variety of other small craft) brought back 338,226 people back to Britain. Of these 140,000 were members of the French Army