The Potsdam conference ends on August 2, 1945. Four days later, the United States drops an atomic bomb on the Japanese city of Hiroshima. A second atomic device is dropped on the port city of Nagasaki three days after Hiroshima. Japan soon surrenders, ending World War II.

But the world has entered the Nuclear Age, a time of unprecedented danger. And that nuclear threat would overshadow all the future Cold War confrontations to come.