World War 1 happened 2 decades earlier and wasn't totalitarian and was nearly as horrific (the combat itself was usually far more horrific than WW2). The legacy of humans has been constant war for centuries before that. Even reducing it to some 20th century political ideology is insufficient. Human history has long been a series of duelling nation states, religions, city states, war lords, tribes, etc.
The only thing that stopped wars was economic production trumped state expansion while becoming global creating strong interconnections between nation states... and technology (ie, nuclear weapons, total war economies) made the stakes of war too high. But again that's just what stopped or slowed down the bloodshed, not a sufficient explanation of why it kept happening.
I'm not aware of any major attacks on civilians in that war.
World War 2 was directed primarily at killing unarmed.
The Nazis wanted to colonize eastern Europe, so killed many to make room for that, as well as anyone that did not fit in with their notion of racial purity. The Japanese killed their millions in China, but also elsewhere. The Italian killing fields were in Ethiopia. The Soviets killed millions of prisoners of war.
Looking at the ideologies of these countries, their goal was to kill anyone who got in the way of those ideologies.
There is nothing controversial about saying that. If you are implying that I'm ignorant of such a basic fact, then this is insulting and commenting in bad faith.
What is controversial nowadays, ironically for a society which claims to be founded on inviolate individual human rights, is that the exact same regard for individual culpability should be accorded members of the Wehrmacht. My previous comment supports the notion of group culpability for members of an army. However, the idea that all members of the Wehrmacht are equally culpable is simply ridiculous and untenable, given the facts and given the principles of individual human rights.
If you're interested in learning more about this history, "The Second World Wars" by Victor Davis Hanson is a good place to start.
If you mean to insinuate that I know nothing of the very basic history of WWII, please know that I am already a fan of David Hanson.
As noted elsewhere, it is an act of individual courage to go against the flow of the groupthink. I hardly think "Nazi German Bad" is at all controversial. However, in 2019, "individual rights for all, no exceptions" is controversial, in direct contradiction to our stated values in the US.
The vast majority of these were killed by Germany, Japan, Italy, and Soviet Union.
While there were individuals who resisted this, the systems of government and the belief systems that drove the totalitarian states where unprecedentedly horrific.
If you're interested in learning more about this history, "The Second World Wars" by Victor Davis Hanson is a good place to start.