But Nuremberg was very successful in de-Nazifying the country. I mean there are neo-Nazi elements in Germany today but they're really fringe elements. If anything they're far less fringe in the United States now (fun fact: the United States had a lot of Nazi sympathizers eg the Nazi rally in Madison Square Garden).
This is where we went wrong with the Civil War: we failed to cull the slave-owning class when such attitudes needed to be snuffed out entirely. I mean Emancipation came with compensating the slave owners rather than the slaves themselves. Lincoln's assassination was really unfortunate here too just because of who his VP was: a Confederate sympathizer who, among other things, pardoned all the secessionists and rebels.
I really wonder if we'd snuffed out the slave owning class and compensated the former slaves where we'd be today. Slavery economics simply moved to the prison system and forced labor.Segregation persisted for another century and the echoes of all that still exist today.