The 20th century civil war which saw the worst massacre of the losers, as a percentage of total population, by the victors is the Finnish civil war of 1918, which lasted 4 month and resulted in the death, mostly through summary execution, of 1% of the population of Finland.
Remarkably, despite such a bloody beginning, the Finnish society healed rather quickly, within 4 years, the losers were incorporated into the Finnish government.
Remarkably, despite such a bloody beginning, the Finnish society healed rather quickly, within 4 years, the losers were incorporated into the Finnish government.