Naval History and Heritage Command

National Museum of the U.S. Navy

Atomic Bombs

Despite the resounding defeats suffered by the Japanese forces in 1944 and early 1945, the enemy showed no intention of ending the struggle in the Pacific.  Consequently, the Allies thought only a conquest of the Home Islands would make the Japanese surrender.   The overall codename was Operation Downfall, with attack on Kyushu being named Operation Olympic and the invasion of Honshu, and subsequently, Tokyo, would be called Operation Coronet.   With the Japanese calling on every able person to fight and thousands of U.S. servicemen either wounded or killed upon invasion, President Harry S. Truman turned to atomic weapons as a solution to the problem.   The two weapons dropped were a uranium gun-type nicknamed "Little Boy" dropped on Hiroshima, Japan, on August 6, 1945, and an plutonium implosion weapon nicknamed "Fat Man" dropped on Nagasaki, Japan, on August 9, 1945.   Accepting the Potsdam Proclamation on August 10, negotations ended with a cease-fire on August 14. 

Image:  80-G-354619:   Atomic Bomb Damage to Hiroshima, Japan, as seen by officers of USS Appalachian (AGC-1).  Photograph recieved October 26, 1945.   Official U.S. Navy Photograph, now in the collections of the National Archives.