I was talking about a specific thing which didn't exactly include the civil war: Specifically the idea of randomly assassinating leaders who represent the "evil" faction (from whoever's point of view), anonymously from out of the crowd. Mass violence as a way of implementing the will of the majority, once the other outlets for implementing it have failed, is a whole other story.

I also agree with you about violence against confederates after the war was over. Read my edit, I realized it and added that as a specific category where we could have used more of that, yes.