WWII: The Atom Bombs and the Decision to Use Them

The Atom Bombs and the Decision to Use Them

The A-Bomb Project

• 1939: German scientists split uranium atoms, creating a nuclear reaction.
• May 1942: FDR created the Manhattan Project, a secret $$2B A-bomb program with 600,000 workers and world-famous scientists.
• Key contributors: Albert Einstein, Enrico Fermi, J.R. Oppenheimer.
• Dec. 1942: The U.S. program successfully created a nuclear reaction; bombs constructed in Los Alamos, New Mexico.

Potsdam Conference & Trinity Test

• Following V-E Day (May 8, 1945), Allied leaders met in Potsdam to decide the fate of post-war Europe and how to defeat Japan.
• July 16, 1945: Truman learned of the successful "Trinity Test" in Alamogordo, New Mexico.
• Allies warned Japan on July 26, 1945, to surrender or face prompt & utter destruction.

Truman's Decision

• Truman made the final decision to use the atom bombs, based on advisers' input.
• Reasons for the decision:
  • Saving U.S. lives & money and shortening the war by 12-18 months.
  • Conventional warfare had not forced a Japanese surrender.
  • Estimates that Japan still had 4 million soldiers ready to fight and die.
  • Gaining an upper hand on the Soviet Union in the post-war negotiations. The Soviet Union was scheduled to enter the war against Japan on Aug 8, 1945
  • Preventing its future use by using it now (deterrent).

The Defeat of Japan

• Aug 6: Little Boy was dropped on Hiroshima (100,000 died).
• Aug 9: Fat Man was dropped on Nagasaki (100,000 died).
• Aug 14: V-J Day; Sept 2, 1945: Japan signed the unconditional surrender!

Result

• The Allies won World War II.
• No country has used the atomic bomb since Nagasaki.
• Tensions with the Soviet Union rose, beginning the Cold War.