The man who became President of the United States after Franklin Delano Roosevelt died was Harry Truman. Truman was Roosevelt’s Vice-President, but he had only been on the job for 82 days when Roosevelt died in April of 1945.
When Truman took over as President, he had never heard about the program that was going on to build atomic bombs. The top secret program had been so top secret, that even the Vice-President of the United States didn’t know anything about it!
About three months after Truman became President, the Trinity Test took place. The Trinity Test was the code name given when the first atomic bomb was successfully blown up in the New Mexico desert. The Trinity Test proved that atomic bombs would work, if they were needed to be used in war.
In August of 1945, the United States was still fighting in World War II against the nation of Japan. Having been told about the successful Trinity Test of an atomic bomb, President Truman decided to drop an atomic bomb on Japan on August 6, 1945. It was his hope that the power of the bomb and the damage it would cause might be enough for the Japanese to stop fighting and surrender. So, an atomic bomb named “Little Boy” was dropped on the city of Hiroshima in Japan. It killed about 80,000 people when it blew up.
When the Japanese didn’t surrender after the “Little Boy” bomb destroyed Hiroshima, President Truman ordered that a second atomic bomb, called “Fat Man”, be dropped on another city in Japan. The “Fat Man” bomb contained plutonium made at Hanford.
On August 9, 1945, an airplane called Bockscar dropped the “Fat Man” bomb over the city of Nagasaki, Japan. Like the “Little Boy” bomb, “Fat Man” caused incredible damage and killed thousands of people.
Several days later, as President Truman considered using even more atomic bombs on Japan, the Japanese decided to surrender and stopped fighting. This brought the end to World War II, partly because of the work done at Hanford to produce plutonium for atomic weapons.