The original "Dunkirk" film with John Mills. My dad who was evacuated from there and self saw it together and he was quite moved by the realism. Another one I enjoyed was "Millions like us" with Patricia Roc, Gordon Jackson and a familiar supporting cast, telling the story mainly of women on the Home front. "The Cruel Sea" was a classic RN saga and closely followed the book which narrated the service of the author Nicholas Monsarrat in the Western Approaches. Hollywood war films are more authentic than they used to be. Years ago, they invariably had the Andrews Sisters popping up and wailing away at the close of the film. At least, they have got away from that scenario!