La Grande illusion

During WWI, three French POWs -- an aristocratic officer (Pierre Fresnay), a Parisian mechanic (Jean Gabin), and a Jewish banker (Marcel Dalio) -- are held in a prison camp under the command of an aristocratic Prussian (Erich von Stroheim). The French officer and his German counterpart find they have a natural social affinity, but their friendship cannot take precedence over wartime duty and patriotism.