Maxmillian Schell gives a ferocious performance in Judgment At Nuremberg as a German attorney defending four judges accused of Nazi war crimes during a post-war military tribunal.
This trial is fiction, but it was based on real proceedings conducted by the allies in the ruins of Germany. Schell isn't just defending judges, including a noble jurist played with quiet intensity by Burt Lancaster, he's standing up for the German people. At one point, Schell's character questions America's moral superiority: what about the women and children killed in Hiroshima and Nagasaki? Spencer Tracy is at his grumpy best in director Stanley Kramer's engrossing, star-studded courtroom drama as the lead justice who struggles to understand how a nation could go mad.
Near the end, reality seeps in: actual footage of concentration camps is shown in the courtroom. Gruesome, heartbreaking, unreal. The horrors of the war were still raw then. They still are.
I just recently re-watched this film (it's been probably 40 years since I saw it) and was riveted from start to finish. The ending when Tracy won't give Lancaster the absolution he seeks is one of the most gut wrenching scenes in all of filmdom...like you say, how can entire country go mad?