The Turks, Mongols & Muslims killed civilians the old fashioned way — the stacked the heads, and stacked them high. (Then the Muslims bitch because the Frankish Crusaders did the same to them when Jerusalem fell, but I digress). I think the horror with Hitler is that he was a throwback who harnessed modern industrial methods to the slaughter. Stalin did it too, but of course he was a necessary ally. By ‘47 we pretty much jettisoned Uncle Joe.
Another thing so horrific about the Nazis is how much death and destruction they caused in just a few years. The persecution and destruction of the Jews was Hitler’s policy from the beginning, but it was ramped up to a frantic pace in 1938 and the Holocaust was a chief priority even towards the end of the war when the Third Reich was crumbling.