WWII in Eastern Europe was a war for the survival of the Slavic peoples whom the Nazis declared to be the Untermensch[0] (Belorussians, Czechs, Poles, Russians, Serbs, Ukrainians – all of them) and were determined to fully exterminate them all following the extermination of the Jews and the Roma people.
The scale of extermination of the Slavs went far beyond the mass murdering of them in concentration camps, and included rounding up villages and burning them along with the villagers down with the use of flamethrowers, with no remorse because the Nazis considered the Slavs sub-humans[1][2][3][4].
Neither Czechoslovakia, nor Poland, nor the Kingdom of Yugoslavia had communism of any shape or flavour.
[0] https://en.wikipedia.org/wiki/Untermensch
[1] https://en.wikipedia.org/wiki/Khatyn_massacre
[2] https://en.wikipedia.org/wiki/Lidice_massacre
[3] https://en.wikipedia.org/wiki/Michni%C3%B3w_massacre
[4] https://en.wikipedia.org/wiki/Memorial_Centre_Lipa_Remembers...