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Atomic Bomb: August 6, 1945

Lesson Author
Required Time Frame
Two class periods
Grade Level(s)
Lesson Abstract
Students will examine motives for dropping the atomic bomb and then evaluate the decisions made.

In the early morning hours of July 16, 1945, great anticipation and fear ran rampant at White Sands Missile Range near Alamogordo, New Mexico. Robert Oppenheimer, director of the Manhattan Project, could hardly breathe. Years of secrecy, research, and tests were riding on this moment. "For the last few seconds, he stared directly ahead and when the announcer shouted Now!' and there came this tremendous burst of light followed abruptly there after by the deep growling of the explosion, his face relaxed into an expression of tremendous relief," recalled General L. R. Groves of Oppenheimer, in a memorandum for Secretary of War Stimson. The explosion carrying more power than 20,000 tons of TNT and visible for more than 200 miles succeeded. The world's first atomic bomb had been detonated.

With the advent of the nuclear age, new dilemmas in the art of warfare arose. The war in Europe had concluded in May. The Pacific war would receive full attention from the United States War Department. As late as May 1945, the U.S. was engaged in heavy fighting with the Japanese at Iwo Jima and Okinawa. In these most bloody conflicts, the United States had sustained more than 75,000 casualties. These victories insured the United States was within air striking distance of the Japanese mainland. The bombing of Pearl Harbor by the Japanese to initiate United States entrance into the war, just four years before, was still fresh on the minds of many Americans.

A feeling of vindication and a desire to end the war strengthened the resolve of the United States to quickly and decisively conclude it. President Harry Truman had many alternatives at his disposal for ending the war: invade the Japanese mainland, hold a demonstration of the destructive power of the atomic bomb for Japanese dignitaries, drop an atomic bomb on selected industrial Japanese cities, bomb and blockade the islands, wait for Soviet entry into the war on August 15, or mediate a compromised peace. Operation Olympia, a full scale landing of United States armed forces, was already planned for Kyushu on November 1, 1945 and a bomb and blockade plan had already been instituted over the Japanese mainland for several months.

The Japanese resolve to fight had been seriously hampered in the preceding months. Their losses at Iwo Jima and Okinawa had been staggering. Their navy had ceased to exist as an effective fighting force and the air corps had been decimated. American B-29's made bombing runs over military targets on the Japanese mainland an integral part of their air campaign. Japan's lack of air power hindered their ability to fight. The imprecision of bombing and the use of devastating city bombing in Europe eventually swayed United States Pacific theater military leaders to authorize bombing of Japanese mainland cities. Tokyo, Nagoya, Osaka, and Kobe all were decimated by incendiary and other bombs.

In all, hundreds of thousands of civilians were killed in these air strikes meant to deter the resolve of the Japanese people. Yet, Japanese resolve stayed strong and the idea of a bloody "house to house" invasion of the Japanese mainland would produce thousands more American and Allied casualties. The Allies in late July 1945 declared at Potsdam that the Japanese must unconditionally surrender.

After Japanese leaders flatly rejected the Potsdam Declaration, President Truman authorized use of the atomic bomb anytime after August 3, 1945. On the clear morning of August 6, the first atomic bomb, nicknamed Little Boy, was dropped on the city of Hiroshima. Leveling over 60 percent of the city, 70,000 residents died instantaneously in a searing flash of heat. Three days later, on August 9, a second bomb, Fat Man, was dropped on Nagasaki. Over 20,000 people died instantly. In the successive weeks, thousands more Japanese died from the after effects of the radiation exposure of the blast. 



incendiary bomb

The incendiary bomb was a mixture of thermite and oxidizing agents employed by the Allies and Axis powers after 1943. Sometimes incorporating napalm, these bombs were responsible for burning over 41.5 square miles of Tokyo by the United States in March 1945.

unconditional surrender

Unconditional surrender is a term used by victors in war to describe the type of settlement they wish to extoll from the vanquished. The settlement demands that the loser make no demands during surrender proceedings. Unconditional surrender was first enunciated by the Allies during World War II at a summit meeting at Casablanca in January 1943. providence divine guidance or care ultimatum the final propositions, conditions, or terms offered by either of the parties during a diplomatic negotiation

Rationale (why are you doing this?)

Students will examine motives for dropping the atomic bomb and then evaluate the decisions made

Lesson Objectives - the student will

1. Analyze primary source documents

2. Examine the advantages and disadvantages of dropping the atomic bomb


District, state, or national performance and knowledge standards/goals/skills met

History—Social Science Stadards for California Public Schools

Grade 10

10.8 Students analyze the causes and consequences of World War II.
Discuss the human costs of the war, with particular attention to the civilian and military losses in Russia, Germany, Britain, the United States, China, and Japan.
10.9 Students analyze the international developments in the post-World World War II world.
Compare the economic and military power shifts caused by the war, including the Yalta Pact, the development of nuclear weapons, Soviet control over Eastern European nations, and the economic recoveries of Germany and Japan.
Discuss the establishment and work of the United Nations and the purposes and functions of the Warsaw Pact, SEATO, NATO, and the Organization of American States.

Grade 11
11.7 Students analyze America's participation in World War II.
Examine the origins of American involvement in the war, with an emphasis on the events that precipitated the attack on Pearl Harbor.
Describe major developments in aviation, weaponry, communication, and medicine and the war's impact on the location of American industry and use of resources.
Discuss the decision to drop atomic bombs and the consequences of the decision (Hiroshima and Nagasaki).

Primary sources needed (document, photograph, artifact, diary or letter, audio or visual recording, etc.) needed

Read the press release from President Truman on August 6, 1945 following the dropping of the atomic bomb noting important details about its production and the rhetoric used.


Fully describe the activity or assignment in detail. What will both the teacher and the students do?

Document Analysis

Distribute copies of the document to each student to read. Ask students to answer the following questions:


  1. Who wrote this document?


  2. What is the purpose of this document?


  3. What date was this document issued?


  4. Why is the name of the city left out?


  5. Why does the atomic bomb's power have to be explained?


  6. Look at the last paragraph of the second page of the press release. What were Truman's plans for ending the war? Did he accomplish those goals in dropping the atomic bomb on Hiroshima and Nagasaki? Why or why not?


  7. On page three, Truman advocates the use of atomic power for world peace. How does he propose to fulfill this goal?


  8. What reasons does President Truman use to justify dropping the bomb?

Follow-Up Questions


  1. Armed with all of the knowledge that President Truman and his advisors had accumulated, how would you have ended the war in the Pacific?


  2. Make a table listing the advantages and disadvantages that the atomic bomb presented to modern warfare? Why did the fire bombing of Tokyo just weeks earlier that killed over 120,000 civilians not receive the same moral criticism that the atomic bomb received? One newspaper critic stated after dropping the bomb, "Yesterday we clinched victory in the Pacific, but we sowed the whirlwind." What did he mean by this? Argue for or against