Hiroshima
On August 6, 1945, the United States dropped the atomic bomb, also known as Little Boy, on Hiroshima, Japan. This bomb killed 80,000 people immediately and took out nearly 90 percent of the city.
Before war broke out in 1939, United States scientists were becoming concerned with the rumors of Nazi Germany researching nuclear weapons. So in 1940, the American gonvernment started funding its own research of atomic weapons so that it could keep up with Germany or possibly get one step ahead. Over the next couple of years, scientists started to try and produce the materials need to make an atomic weapon (such as uraniu-235 and plutonium). After many years of working hard on making nuclear weapons, on July 16, 1945 The Manhattan project had its first testing of a plutonium bomb in New Mexico.
By the time the U.S. did the atomic bomb test, Germany had already surrendered. But Japan promised that they would die before they surrendered. Between April and July of 1945, Japan had caused about half of the U.S. casualties than it did in three full years at war. And when the U.S. asked if Japan would surrender in the Potsdam Declaration, Japan denied and America said they would face "prompt and utter destruction".
Most of the military favored the conventional bombing that they had been doing for the past couple of months. They were also planning on invading Japan in what they codenamed "Operation Downfall". After lots of time of thinking, they all advised Truman not go with the invasion because it was speculated that the U.S. would have up to 1 million casualties. So Truman decided to go with atomic bomb to make the war end quickly and put the U.S. on the map to controlling the postwar world.
Nagasaki
After the bomb dropped on Hiroshima, Japan was still not going to surrender to the U.S. The U.S. had decided that it was going to drop its second A-bomb, Fat Man, on Nagasaki, Japan on August 11. When bad weather was supposed to hit that day, the dropping of the bomb was pushed up to August 9. The bomb was dropped at 11:02 a.m. and it was was speculated that it killed around 60,000 to 80,000. After this second bomb, the creator of the Manhattan Project said that a third bomb would be ready by August 17 or 18 but it was never needed. The Japanese Emporer finally surrendered because he said that "continuing the war can only result in the annihilation of the Japanese people...".
