They murdered Rosa, they murdered the Ruhr Red Army, they murdered Levine and the Bavarian Council Republic by aligning with the military, they wiped out the Bremen Soviet Republic, they carried out Blutmai, put down the March Action, among a shitload of other things.

I do really loath the "such and such war wouldn't have happened" thing, I especially try not to do it with WWI AND WWII, but if anything applies it is the literal creation of the Friekorps