Seventy-five years ago this month, the United States used the most powerful weapons developed until that time to attack the cities of Hiroshima and Nagasaki. Because the atomic bombings caused such extraordinary damage amid an already-disrupted wartime Japan, the number of people who died as a direct result of the attack can’t be pinpointed. Initial US military estimates placed the immediate death toll at 70,000 in Hiroshima and 40,000 in Nagasaki. Later independent estimates suggest that 140,000 people died in Hiroshima and 70,000 were killed in Nagasaki.