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Ernest Rutherford discovers the proton by artificially transmuting an element (nitrogen into oxygen).
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Period: to
The Manhattan Project
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The Great depression
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Ernest O. Lawrence builds the first cyclotron in Berkeley.
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James Chadwick discovers the neutron.
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J. D. Cockroft and E. T. S. Walton first split the atom.
This proved Einsteins Theory of Relativity. -
Holocaust begins
The Holocaust, also known as the Shoah, was a genocide in which Adolf Hitler's Nazi Germany and its collaborators killed about six million Jews. -
F.D.R. is elected president
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Bohr reports on the Hahn-Strassman results at a meeting on theoretical physics in Washington, D. C.
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The Great Depression ends
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Albert Einstein writes President Franklin D. Roosevelt, alerting the President to the importance of research on chain reactions and the possibility that research might lead to developing powerful bombs.
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Germany invades Poland.
World War II begins. -
Alexander Sachs discusses Einstein's letter with President Roosevelt. Roosevelt decides to act and appoints Lyman J. Briggs head of the Advisory Committee on Uranium.
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Roosevelt informs Einstein that he has set up a committee to study uranium.
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Glenn T. Seaborg's research group discovers plutonium.
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Bush briefs Roosevelt and Vice President Henry A. Wallace on the state of atomic bomb research. Roosevelt instructs Bush to find out if a bomb can be built and at what cost. Bush receives permission to explore construction needs with the Army.
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FDR authorizes the Manhattan Engineering District
FDR authorizes the Manhattan Engineering District for the purpose of creating an atomic bomb. This would later be called the 'Manhattan Project'. -
Roosevelt approves production of the atomic bomb.
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Japanese Relocation
President Roosevelt signed an executive order in February 1942 ordering the relocation of all Americans of Japanese ancestry to concentration camps in the interior of the United States. -
The Manhattan Engineer District is established in New York City, Colonel James C. Marshall commanding.
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Colonel Leslie R. Groves is appointed head of the Manhattan Engineer District.
He is promoted to Brigadier General six days later. -
Military Policy Committee
Secretary of War Henry Stimson creates a Military Policy Committee to help make decisions for the Manhattan Project. -
Groves selects Los Alamos, New Mexico as the bomb laboratory (codenamed Project Y). Oppenheimer is chosen laboratory director.
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Roosevelt approves detailed plans for building production facilities and producing atomic weapons.
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Bomb design work begins at Los Alamos.
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Japan becomes target
Japan becomes the primary target for any future atomic bomb according to the Military Policy Committee of the Manhattan Project. -
President Roosevelt approves the S-1 Executive Committee recommendation
President Roosevelt approves the S-1 Executive Committee recommendation to proceed to the pilot plant stage and instructs that plant construction be the responsibility of the Army. The Office of Scientific Research and Development continues to direct nuclear research, while the Army delegates the task of plant construction to the Corps of Engineers. -
Bomb models are tested at Los Alamos.
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The plutonium gun bomb (code named Thin Man) is abandoned.
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Tokyo is firebombed, resulting in 100,000 casualties.
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President Roosevelt dies.
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Possible targets for the atomic bomb
The Target Committee of the Manhattan Project select four cities as possible targets for the atomic bomb. They are: Kyoto, Hiroshima, Kokura, and Niigata. -
War ends in Europe
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Holocaust ends
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Tokyo is firebombed again.
This time resulting in 83,000 deaths. -
Leo Szilard begins a petition to get President Truman to call off using the atomic bomb in Japan.
Leo Szilard begins a petition to get President Truman to call off using the atomic bomb in Japan. -
Los Alamos scientists successfully test a plutonium implosion bomb in the Trinity shot at Alamogordo, New Mexico.
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President Truman orders atomic bombs to be used.
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The 509th Composite Group is ordered to attack Japan with an atomic bomb "after about" August 3.
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Japan Surrenders
Truman, Chinese President Chiang Kai-Shek, and new British Prime Minister Clement Atlee issue the Potsdam Proclamation, calling for Japan to surrender unconditionally. -
Potsdam Declaration is rejected by Japan
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Bombing of Hiroshima
The gun model uranium bomb, called Little Boy, is dropped on Hiroshima. It kills between 90,000 and 100,000 people immediately. Truman announces the raid to the American public. -
Bombing of Nagasaki
The implosion model plutonium bomb, called Fat Man, is dropped on Nagasaki. (it was scheduled to be dropped at Kokura. However, because of poor weather the target was moved to Nagasaki.) -
Japan surrenders.
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President Truman signs the Atomic Energy Act of 1946.
A slightly amended version of the McMahon bill.
