Seventy years ago today, August 6, 1945, the U.S. dropped the world's first atomic weapon
on the city of Hiroshima, Japan. Three days later, a second bomb was dropped on Nagasaki, and Japan surrendered on August 15, ending World War II. Those events ushered in the nuclear era.
Digg has a list of links to articles about the first atomic bombing.
Neatorama also has some essential reading material on the subject.
Nuclear Quotes: The Crew of the Enola Gay