It was written by Jean Renoir and Charles Spaak, and directed by Renoir. It has a very strong anti-war message and portrays both the French prisoners and German captors in a sympathetic light.
One of the recurrent themes running through it is the difficulty that we face in overcoming the barriers of language and class; the optimistic message of the movie is that at least some of these barriers can be overcome with enough persistence. Marechal, the character played by Jean Gabin, finally learns to speak a few words of German, although not quite correctly; Dita Parlo, who plays Elsa, speaks a few halting words in French.
On the other hand, those characters who already understand each other--the aristocrats de Boildieu Pierre Fresnay and von Rauffenstein Erich von Stroheim--and feel a bond of kinship that transcends national divisions also understand that their days are numbered. One of them kills the other; the one who survives considers his friend and victim to be the lucky one.
The movie was nominated for the Academy Award for Best Picture, the first foreign language film to be nominated in this category. It was thought to be lost in the chaos of World War Two, until a print surfaced some years later.