The Capone era in Chicago has to be one of the most violent in history by far. Those fuckers were killing and leaving bodies on the ground every other day it seemed like.
The Chop Shop wars of the 1970's got pretty violent also in regards to the Chicago mob.
No doubt about that.
But the thread is focused on the "leaderships" of Families, per se. Not just gangland killings.
But dating way back to their earliest days, the did have Big Jim Colosimo, the Gennas, Joe Aiello and a few others. So Chicago definitely had their fair share of hierarchy-type killings.