Reasons for, and significance of, US use of atomic weapons against Japan

Manhattan Project

  • The discovery of the fission of a uranium atom led to the proposition of using this nuclear energy to build a bomb. This discovery was made in Germany, but news of it made its way to the USA.

  • FDR created the Manhattan project to build the bomb before Germany could. In total, the project encompassed 130,000 people and it spent 2.2 billion dollars in research. It was located around the USA. Notable sites include Oak Ridge, Tennessee; Hanford, Washington; and Los Alamos, New Mexico.

  • It was a top secret operation, which most Americans did not know about. People who worked on the project either did not know what they were working towards, or they were not allowed to disclose any information to any outsiders.

  • The Los Alamos site was led by J. Robert Oppenheimer, who became known as the father of the nuclear bomb.

  • On July 16th, 1945, a test bomb was dropped in the New Mexico desert. This bomb resulted in a crater 1,000 feet wide and 10 feet deep. A month later, the bombs would be dropped on Nagasaki and Hiroshima.

    Okinawa disaster made planners weary of invasion of Japanese mainland (Honshu/Kyushu)

    • Every single person will fight to the death

    • Giant casualty estimates

  • Japanese threats against US POWs

    • If Americans landed troops on Japan all POWs would be killed

  • Assumption of Use - WHY

    • Project was expensive

    • Revenge for pearl harbor

    • Casualty estimates

    • Japanese casualties

    • Nonmilitary demonstration

  • Potsdam Conference July 1945

    • Truman’s ultimatum to Japan

      • Gave such harsh conditions (can’t have an emperor and unconditional surrender) that Japan WILL NOT accept so they have an excuse to drop the bomb

    • Soviet “peace feelers”

  • Japanese Surrender w/o the bomb

    • Probably 

    • Bomb never mentioned during the vote of whether or not to surrender

    • Soviet entry into the war likely was more significant factor

    • Even if you can excuse the first bomb you cannot excuse the second bomb bc Japan had no idea how many bombs / bomb resources the US had (we could have had 1000s)

  • The US now had an ATOMIC MONOPOLY - in the early Cold War day, this resulted in ATOMIC DIPLOMACY