1. Unit 2: The Second World War and the Americas (1933–1945) Bullet 5: Reasons for, and significance of, US use of atomic weapons against Japan

2. The Dropping of The Atomic Bomb at Hiroshima and Nagasaki “The atom bomb was no great decision. It was merely another powerful weapon in the arsenal of righteousness.” ~ Harry S. Truman (POTUS) 1

3. Nuclear Programs: Germany Germany started experimenting with Nuclear Fission in 1938. German scientist Otto Hahn and Fritz Strassman bombarded Uranium with neutrons and discovered Barium atoms. Conclusion: Nuclear fission releases a massive amount of energy 2

4. No Bomb for the Germans June 1942 – German atomic program slows down because Germany felt victory in WWII was imminent. U.S. and Britain were not aware that the Germans decided not to build a bomb. Japan also had an atomic program but was not successful. If Germany and Japan had created an atomic bomb, it would be used against the Allies. 3

5. The Manhattan Project June 1942, atomic-bomb project was controlled by War Department's Army Corps of Engineers. American and European physicists discovered that the fission of uranium could a powerful weapon. Major General Leslie Groves named head of the project. At the height of construction in mid 1944, the Project employed nearly 129,000 people. No other nation in the world had the massive industrial capacity to make this possible. 4

6. Robert J. Oppenheimer Late in 1942, Gen. Groves chose physicist J. Robert Oppenheimer to head a new laboratory devoted to the designing atomic bombs. Oppenheimer recommended a remote site in New Mexico for the new facility, where many famous scientists could work together in complete secrecy. From a wealthy N.Y. Jewish family. Ties with Communism 5

7. The Manhattan Project Success Two atomic bombs were made, “Little Boy” and “Fat Man.” Scientists at Los Alamos were not fully confident in the “Fat Man” bomb. Bombs designed to create an accurate and symmetrical implosion. 6

8. Fat Man and Little Boy “Fat Man” “Little Boy” 7

9. Battle of Okinawa Known as “Typhoon of Steel” 8

10. Deciding to Drop the Bomb 9

11. 1.Ending the war at the earliest possible moment 2.To justify the cost of the Manhattan Project 3.To frighten the Soviets 4.A lack of incentives not to use the bomb 5. Responding to Pearl Harbor 10

12. Ending the war at the earliest possible moment The primary objective for the U.S. was to win the war at the lowest possible cost. Specifically, Truman was looking for the most effective way to end the war quickly, not for a way to not use the bomb. - Allied prisoners of war were beaten, deliberately starved, tortured, worked to death and even experimented on with chemical & biological weapons by the Japanese. - Some were even crucified on trees and beheaded by their captors! 11

13. Ending the war at the earliest possible moment 12

14. To justify the cost of the Manhattan Project 14

15. To Frighten the Soviets At the Yalta Conference in March 1945, the big three agreed that there should be early free elections in Eastern European countries like Poland as soon as the war was over. RIP 15

16. To Frighten the Soviets By the time the big three met again at Potsdam on 23 rd July 1945, Stalin did not trust the Americans. He is trying to spread Communism! We have been attacked twice in less than 25 years! 16

17. A lack of incentives not to use the bomb By 1945, the bombing of civilians was already an established practice. 17

18. Responding to Pearl Harbor When a general raised objections to the use of the bombs, Truman responded by noting the atrocities of Pearl Harbor and said that “When you have to deal with a beast you have to treat him as a beast.” On 7 th December 1941, 2400 American servicemen, six battleships and ten other ships were destroyed during a surprise attack by the Japanese. 18

19. Alternatives to dropping the bomb 1. Intensifying conventional bombing and the naval Blockade 2. Allowing the Japanese to retain the Emperor 3. Waiting for the Soviet Union to enter the war 19

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21. Formal Warning to Japan 21

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25. Imperial Rescript on Surrender 23

26. Post-war Impact of Atomic Bomb Changed the very nature of war o Presented the possibility of annihilation of humankind 24

27. Post-war Impact of Atomic Bomb US held an atomic monopoly until 1949 o Huge US-USSR arms race followed o Eventually led to Mutually Assured Destruction (1967) 25

28. Post-war Impact of Atomic Bomb Nuclear weapons prove to not be a reasonable option in limited wars This seen in the Korean and Vietnam War 26