OKAY!
Gettysburgh (Civil War, great artillery)
Flight of the Intruder (Daniel Dafoe, Vietnam, air war)
Bat 21 (Gene Hackman, Danny Glover, Vietnam, air war)
The Lost Battalion (WW1, infantry)
The Big Red One (Lee Marvin, WWII, infantry)
The Good, The Bad, And The Ugly (Clint Eastwood, Civil War, free lancers caught in war)
A Piece Of Cake (BBC series, WWII, early air war over France and Britain, lotsa Spitfires and Messerschmidts)
Memphis Belle (WWII, air war, bombers)
These are a few of my favorites, there are so many.