An excellent World War II/Holocaust film that does not get nearly the credit it deserves is the Louis Malle-directed French masterpiece, Au Revoir Les Enfants (1987).
This gritty and gripping film follows a French boarding school run by priests that seems to be isolated from WWII. That all changes when a secret emerges that one of the boys is Jewish.
It is an autobiographical film, written, produced, and directed by the great Malle.