Atomic
It never occured to me that the US bombing of Japan during World War II probably resulted in the most people dying simultaneously (or within a rather short amount of time) in the history of humanity.
I just watched the documentary White Light, Black Rain. Despite knowing “about the bomb” and “about the situation,” I never really knew what happened immediately after and hear first-hand from survivors what it was like. It’s difficult to imagine or put into perspective the deaths of 210,000 human beings, but this documentary does a an excellent job trying to capture such an ineffable situation.