U.S. drops an atomic bomb on Hiroshima in Japan.

The explosion at 8:15 a.m. and subsequent radioactive poisoning kill some 140,000 people. When the Japanese government does not surrender, the U.S. drops a second bomb on the city of Nagasaki three days later. The Japanese government does surrender five days after that.* The atomic bomb was first tested successfully near Alamogordo, New Mexico, on July 16, 1945.