Here are some I've watched (or re-watched) recently that haven't been mentioned yet, unless I missed it.
Paisan, Rome Open City and Germany Year Zero
Au revoir les enfants
Five Graves to Cairo
The Battle of Stalingrad (three hours of risible and gripping, by turns, pro-Stalin propaganda)
In Which We Serve
And if Shoah qualifies, then I would also cite The Sorrow and the Pity.