Hmmm...no mention of Stalag 17. Great movie.

And, if we go into TV series, 12 O'Clock High i saw as a kid (barely remember it, though, and never see it replayed), and the quintessential "Combat" starring Vic Morrow and Rick Jason among others. It was just about as good and sometimes better than most movies about war, and yet it was an ongoing TV series! It finally halted due to expense.
If you've never seen that series then you must check it out.