The KKK had no connection with leftism. The other groups did. And Eric Foner, who is cited as an authority by Jeffery Lord, is a Marxist:
https://historyhalf.com/eric-foner-preaches-marxism-on-campus/
BTW, you still a neverTrumper? Or did you give that up?
Brown shirt Klantifa, all evil, all the time.
You forgot Antifa.
And BLM.