Can't understand WWII without understanding Russia either, but it's too big a topic to be lumped under WWII. Could say the same for China and Japan, so maybe will move those movies to their own threads.
The real kicker here is to understand that Russia, kinda like Israel, is actually forged based on FAITH. Reading between the lines in the video below, you find out that the 2nd generation post-conversion to Christianity, treated its slain but coulda-been kings, as martyrs for Christ. The entire doctrine, imported and mutated from apostate Constantinople, makes the people under it, easy targets for the later Communism. Accounts for how very much, the first and second generation of Communists, so fervently believed in it.
So let's see how all this started...https://www.youtube.com/watch?v=AEmUIfF2uAk
On Stalyin (the 'y' sound is tacked on the 'i' in Russian, so that's why I add the 'y'):https://www.youtube.com/watch?v=SIzApqzlP3Qhttps://www.youtube.com/watch?v=-K6-jl13Umkhttps://www.youtube.com/watch?v=deafhAt_Qo4https://www.youtube.com/watch?v=VAILCsH7PRIhttps://www.youtube.com/watch?v=WTv9iZJvx1Q