Band of Brother (altrough not a movie)
Blackhawk Down
SPR (altrough I have mixed feelings about this. It's not WW2, it's Spielberg-war. also, there were some realism-errors)
Das Boot
Last of The Mohicans (not a war-flick as such, but had great battle-scenes)
The Winter War (I might be biased, but many america war-enthusiasts think that it's one of the best and most realistic war-movies ever made)
Haven't seen Glory yet, but I'm planning to. It might make it to the list as well