Anarchism

To be fair, in the German context the conservatives were also terrified of the socialist democrat party, who were relatively moderate and if I remember correctly did not have too close ties with Soviet. Hindenburg made the fatal mistake of being more afraid of moderate socialists than of radical fascists.

I also wouldn't give Stalin too much credit for defeating Hitler. The Soviet Union only turned on Germany when they were invaded, and Stalin's military strategy was ruthless and incredibly inefficient. When the Red Army freed Europe I'd argue it was in spite of Stalin rather than because of him.

Maybe I'm looking at history with a view to avoid giving Stalin credit for anything, but turning on a fascist country only when they invade you does not impress me much, and ordering your soldiers to march into a meat grinder without weapons is not an efficient military strategy.