During the final stages of World War II in 1945, the United States conducted two atomic bombings against Japan in the cities of Hiroshima and Nagasaki.
By executive order of President Harry S. Truman the U.S. dropped the nuclear weapon Little Boy on the city of Hiroshima on Monday, August 6, 1945, followed by the detonation of the bomb Fat Man over Nagasaki on August 9 (After 3 days, don't feel guilty with their action).
The bombs killed as many as 140,000 people in Hiroshima and 80,000 in Nagasaki by the end of 1945, with roughly half of those deaths occurring on the days of the
bombings. Amongst these, 15–20% died from injuries or the combined
effects of flash burns, trauma, and radiation burns, compounded by illness, malnutrition and radiation sickness. Since then, more have died from leukemia (231 observed) and solid cancers (334 observed) attributed to exposure to radiation released by the bombs. In both cities, most of the dead were civilians.
