The First Atomic Bombs

On August 6th, 1945, and August 9th, 1945, two atomic bombs were dropped on two Japanese cities: Hiroshima and Nagasaki. The first bomb did not achieve the goal of dropping it, which is causing the Japanese to surrender. 3 days after that bomb, the second bomb was dropped on Nagasaki. This finally caused the Japanese to surrender.
The bomb dropped on Hiroshima was nicknamed "Little Boy", while the bomb dropped on Nagasaki was nicknamed "Fat Man".
Harry S. Truman, the president during the event, debated on whether or not to use the bomb in the first place. Many Americans were against it and believed it was cruel and unnecessary. Winston Churchill of Britain was for the bomb as well, and Joseph  Stalin of Russia was not notified, although he knew about the bombs before Truman did through the use of spies. Once Truman decided, he lost a lot of  his supporters in the US.

"Little Boy" (Left) used on Hiroshima and "Fat Man" (Right) used on Nagasaki.

The Potsdam Conference was a peace conference between the US, Britain, and the Soviet Union. Joseph Stalin, Winston Churchill, and Harry Truman all gathered in occupied Germany to discuss Japan and the Nazi's  punishment after being defeated. They agreed to unconditional surrender, meaning they had no say in the punishment.