Yes, there are a number of past regimes that were exceptionally guilty...while all of them were guilty to some extent. It's become fashionable to drag out the Nazis as an exclusive example of extraordinary evil whenever the subject of organized evil comes up, but they were certainly not alone in that respect.

Nor were they alone in the fact that the majority of their own population at the time had no idea they were helping to support evil causes, but went forth with much the same sense of idealism and sense of moral rightness in their minds as people in other places did. They were very badly led.

When an organized evil is made "normal" in a society (usually for financial purposes or imperial ambitions), most people there at the time take it as normal and they don't question it. They accept it. They would be quite upset by someone who questioned it. That sort of thing has been going on ever since civilization came into existence. It's only with the clarity of hindsight following a great social change that a population comes to realize that a great wrong has been committed by what was previously seen as "normal".

In Rome, for example, anyone with a reasonable amount of money owned slaves. And that was seen as perfectly normal. It wasn't normal by our standards, but it was normal by the standards of Rome and most nations around Rome at that time in history. They would have been rather annoyed with someone who came and lectured them about it, I imagine...because to them it was just a normal practice.

There are always a few radicals in any society, though, people of exceptional vision and independence of mind, who question such normalities and suggest that they are immoral and wrong. Such radical thinkers are considered "troublemakers" by the vast majority of people around them. ;-) Sometimes they are compelled to shut up in various ways, in fact, because they disturb the steady flow of "business as usual" and people don't like that. Socrates was made to drink poison. Martin Luther was excommunicated. The examples of that sort of thing are endless.