You might like this graph of global war deaths by year from 1800 to present:
https://ourworldindata.org/grapher/deaths-in-wars
World War 2 vastly overshadows all other conflicts. Something like 3.7% of the global population died. Some individual countries lost more than 10% of their populations. No other conflict, or group of regional conflicts, comes anywhere close.
I wish the graph in the link had an option to normalize by population. I bet a graph of war deaths as a percent of global population would look very peaceful over the past 50 years.
Edit to add a link about my 10% population number:
https://www.statista.com/statistics/1351638/second-world-war-share-total-population-loss/