To Hell and Back, The Man Who Never Was, Guns of Navarone were some of my favorites not yet mentioned.
Nobody has mentioned Longest Day (unless I missed it).
Great film about the D-Day invasion with an amazingly star studded cast. John Wayne, Richard Burton, Sean Connery, Robert Mitchum, Henry Fonda, and a bunch of others you’d recognize as major stars of the time.
Covers the battle from generals on down to privates. Same director and writer as A Bridge too Far.
Quite a long movie at 178 minutes.