There have been many, but Renoir's Le Grande Illusion, is probably the movie that had the most impact on me.
[ame=http://www.youtube.com/watch?v=hctrYzVYmfM]La Grande Illusion (1937) Trailer - YouTube[/ame]
[ame=http://www.youtube.com/watch?v=hctrYzVYmfM]La Grande Illusion (1937) Trailer - YouTube[/ame]