“Battleground (1949)” is a classic combat drama about the men who held the line the Battle of the Bulge. It is surprisingly unsentimental for its time and place, and marked by touches of droll humor. Realistic without an excess of gore, pyrotechnics, or jinogism, it remains one of the best films of its kind (“Band of Brothers is one of the few in its class). William Wellman directed. “Stalag 17” (1953) is something else, a POW whodunit, kind of like Agatha Christie meets Hogan’s Heroes. If you are not put off by the incongruity of the tone and setting, it’s enjoyable mystery, in a 50s kind of way. Directed by Billy Wilder.