Yep, starting with failure to define and declare war against belligerent nations states instead of dodging with “war on” catch phrases.
Releasing POWs back to countries that were thoroughly defeated wasn’t a problem because they were being released to a nation that had lost the will to fight.
There were still nazi sympathizers in postwar Germany who tried to carry on a guerrilla war against the allies but within a couple of years the German people themselves rose up against them.