Honestly one of the most brutal and affecting films I have ever seen. "Come and See", directed by Elem Klimov, tells the story of a young boy who joins a group of Soviet partisans on the Eastern Front of WW2, specifically in Belarus, 1943.
Its treatment of war from the perspective of powerless bystanders is both harrowing and haunting. The cinematography and the use of surrealist elements in this movie still hold up beautifully. Perhaps most importantly, the message this film bears is enduringly relevant. If you've got a couple of hours to kill, and don't mind reading dialogue, I strongly suggest that you watch it. You will not regret it.
EDIT: Come and See was released in 1985, not 1981, my mistake
The House With A Clock In Its Walls