Energy Timeline
from 1939 to 1950
1939-1950 1951-1970 1971-1980 1981-1990 1991-2000 2001 2002 2003 2004
August 2, 1939 Albert Einstein writes President Franklin D. Roosevelt, alerting the President to the importance of research on nuclear chain reactions and the possibility that research might lead to developing powerful bombs. Einstein notes that Germany has stopped the sale of uranium and German physicists are engaged in uranium research.
September 1, 1939 Germany invades Poland. World War II begins.
December 7, 1941 The Japanese attack Pearl Harbor. The United States enters the war.
January 19, 1942 President Roosevelt approves production of the atomic bomb following receipt of a National Academy of Sciences report determining that a bomb is feasible.
June 17, 1942 President Roosevelt instructs the Army to take responsibility for construction of atomic weapons complex. The Army delegates the task to the Corps of Engineers, which establishes the Manhattan Engineer District.
September 19, 1942 Brigadier General Leslie R. Groves, head of the Manhattan Engineer District, selects Oak Ridge, Tennessee, site for facilities to produce nuclear materials. Isotope separation of uranium235 takes place in the gaseous diffusion plant built in the K-25 area of the site, in the electromagnetic plant in the Y-12 area, and in the liquid thermal diffusion plant. A pilot pile (reactor) and plutonium separation facility are built and operated at the X-10 area.
November 25, 1942 Groves selects Los Alamos, New Mexico, as site for separate scientific laboratory to design an atomic bomb.
December 2, 1942 Metallurgical Laboratory scientists led by Enrico Fermi achieve the first self-sustained nuclear chain reaction in pile constructed under the west grandstand at Stagg field in Chicago.
January 16, 1943 Groves selects Hanford, Washington, as site for full-scale plutonium production and separation facilities. Three reactors--B, D, and F--are built.
April 12, 1945 President Roosevelt dies. Harry S. Truman becomes President.
May 7, 1945 Germany surrenders.
July 16, 1945 Los Alamos scientists successfully test a plutonium implosion bomb in the Trinity shot at Alamogordo, New Mexico.
August 6, 1945 The gun model uranium bomb, called Little Boy, is dropped on Hiroshima, Japan.
August 9, 1945 The implosion model plutonium bomb, called Fat Man, is dropped on Nagasaki, Japan. Five days later, Japan surrenders.
June 14, 1946 Bernard Baruch presents the American plan for international control of atomic research to the United Nations. The Soviet Union opposes the plan, rendering it useless.
August 1, 1946 President Truman signs the Atomic Energy Act of 1946.
January 1, 1947 In accordance with the Atomic Energy Act of 1946, all atomic energy activities are transferred to the newly created Atomic Energy Commission.
June 23, 1948 Soviet Union begins blockade of West Berlin.
August 29, 1949 Soviet Union detonates first atomic device.
January 31, 1950 President Truman instructs the Atomic Energy Commission to expedite development of a thermonuclear weapon.
June 25, 1950 North Korea invades South Korea. The Korean War begins.
October 9, 1950 President Truman approves a $1.4 billion expansion of Atomic Energy Commission facilities to produce uranium and plutonium for nuclear weapons.
Last Reviewed: 12/4/2007
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