Saving Private Ryan ... the opening sequence.
That may be the most realistic battle scenes ever filmed, at least according to a WWII vet who landed on Omaha Beach that I once spoke with. It's among the most horrific things I've ever seen in a movie, and I'm so glad that I never saw this movie in a theater, instead only on the small screen.
This list though, is for "Fictional Battles," which I guess the last battle was. But the D-Day invasion at Omaha Beach was all too real.
Mark