From: Federal Way, WA
One of my favorites that hasn't been mentioned yet is "The Caine Mutiny" -- sort of the Pacific naval counterpart to "Twelve O'Clock High," though admittedly not quite up to the same standard.
I've always liked "Run Silent, Run Deep," but the more I learn about reality the less I like it's concessions to Hollywood's idea of a good war movie (and I am NOT a great fan of Burt Lancaster). Can't think of my other favorites right now, there are so many of them (and so many duds).
Interesting to see at least one comment that agrees with something I said just last week. My brother and I had a "military movie marathon" day, and I mentioned that most war movies seem to go on too long with the actual battle scenes. The quality of the scenes might be high, as in "Tora! Tora! Tora!", but there comes a point where yeah, we get it, there's a lot of fighting going on. The half-hour of battle scenes in that movie could be cut back to 10 minutes without losing the effect (maybe 15, to keep the Tyler and Welch drama intact). Same goes for "Master and Commander," where the battle on board the Acheron is longer than necessary. Maybe I'm just getting old, but action scenes for the sake of action scenes just don't do it for me anymore.