Well we already know J6 is the worst calamity of the 21st Century.
Wonderfully, bitterly ironic.
Given the murderousness of governments of all sorts throughout the 20th century, the assertion of anything other than clear truths is evil.
For a comprehensive study, until Professor Rummel's death, see: "Freedom, Democracy, Peace; Power, Democide, and War"
Lots of documentation.
https://www.hawaii.edu/powerkills/
Historians in the year 3000, looking back at the previous 1000 years, will no doubt pronounce Jan. 6, 2021, the worst calamity of the third millennium.