Not many spring to mind. I guess war has enough horror on it's own, compared to, say, a summer camp with the young counselors. Heavy Metal has the segment with the B-17 and the airplane graveyard.
Not movies, but...
Anyone remember the "Wierd War Tales" comics of the 1970s? Ghost Boat was a great horror book with a WW2 US submarine theme. They did make a movie later, but set it on a lost liner. Thought the movie was OK.
Charon