The swiss Sonderbund war (an 1847 declared protestant/catholic civil war), with ~100 deaths, was resolved much less[0] bloodily than the 1861 US civil war (hundreds of thousands dead). I was rating "squabble" because unless I am miscounting, the total number of partisan deaths directly[1] attributable to current US divisions are still only ~10.
[0] come to think of it, less even than the "Alamo": like the US civil war, also in defense of slavery.
[1] NB possible "stochastic terrorism" not included; excess deaths due to fear of vaccination definitely not included.