It’s really quite simple, and the historical truths are apparent in spite of the myths created among leftists in the west.
The Nazis stood for “national socialist”. They were socialists but they opposed the Commintern led by the Bolsheviks. Thus their true political cousins, the Communists, were among their opponents.
Unlike the “internationalists” associated with the Commintern, the Nazis were German nationalists in their international outlook - which, given the lopsided WWI treaties was not so strange, with or without a Hitler.
All across Europe, at the local level, Communists and Nazi sympathizers easily changed back and forth between their “red” shirts and their “brown” shirts, depending on which armies were succeeding in their area at the time.
They both stood for socialist dictatorships and tearing down Europe’s liberal, western traditions founded in Europe’s religious and philosophical history.
But the propaganda machine of the Marxists has been working constantly, since WWII, selling the myth that there was some grand “political” alliance between western democracy at the international Marxists, epitomized in the military alliance between the western allies and the Soviet Union.
But the fact is that the west would have been allied with Russia against Germany if Russia had still been Czarist Russia. The alliance with the Soviets was an alliance of convenience and nothing more, in spite of the left’s myths.
In effect, we are told that the Russian socialist empire is at the other end of the ideological spectrum from the German socialist empire. This really does not make sense. One way this has been popularized is to present a horseshoe continuum that has the “far right” very close to the “far left.” It is the only horseshoe continuum I am aware of. Let’s try the idea elsewhere. The basketball player was so tall, he was almost a midget. The temperature in the core of the sun is so high, it approaches absolute zero. Obviously, horseshoe continuums make no sense either. Many Americans have been indoctrinated with nonsense. By contrast, this article is well researched, is consistent with writings by such people as Hayek, Mises, and Sowell, and it makes sense.