...I recommend two similar films by G. W. Pabst:

Der letzte Akt (1955) Es geschah am 20. Juli (1955)

The remarkable aspect of these films are the proximity to the war itself. These are German/Austrian films from a time where neither nation wanted to deal with the haunting shadows of their recent past. Also, they both seem to form the basis for newer adaptions of the same subject, "Der letzte Akt" for "Der Untergang" and "Es geschah am 20. Juli" for "Valkyrie".