There really was a German resistance movement after V-E Day. It was never very effective; it got off to a very late start, as the Nazis took much longer than they might have to realize they weren't going to win the straight-up war. And it was hamstrung because the Wehrmacht, the SS, the Hitler Youth, the Luftwaffe, and the Nazi Party all tried to take charge of it- which often meant, for all practical purposes, no one took charge of it. By 1947, it had mostly petered out.
Harry Turtledove