| Historic
Timeline of the Development of the Atomic Bomb and Oak Ridge, Tennessee |
| |
| 1900 - 1905 |
| Turn of the Century |
John Hendrix has a vision that one day, “Bear Creek
Valley will be filled with great buildings and factories, and they will help
toward winning the greatest war that ever will be…” |
| April 22, 1905 |
Germany invades Poland |
| 1939 |
| October 11 - 12, 1939 |
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. |
| November 1, 1939 |
The Uranium Committee meets for the first time. |
| 1941 |
| Mar. 1941 |
John R. Dunning and his colleagues demonstrate that
fission is more readily produced in the rare uranium-235 isotope, not the
more plentiful uranium-238. |
| February 24, 1941 |
Glenn T. Seaborg's research group discovers
plutonium. |
| March 28, 1941 |
Seaborg's group demonstrates that plutonium is
fissionable. |
| May 1, 1941 |
Seaborg proves plutonium is more fissionable than
uranium-235. |
| June 22, 1941 |
Germany invades the Soviet Union. |
| July 2, 1941 |
The British MAUD report concludes that an atomic
bomb is feasible. |
| October 9, 1941 |
Vannevar Bush, head of the Office of Scientific
Research and Development, 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. |
| December 7, 1941 |
The Japanese attack Pearl Harbor. |
| December 10, 1941 |
Germany and Italy declare war on the United States. |
| December 18, 1941 |
The S-1 Executive Committee (which replaced the
Uranium Committee in the Office of Scientific and Research Development) gives
Ernest O. Lawrence $400,000 to continue electromagnetic research. |
| 1942 |
| January 19, 1942 |
Roosevelt approves production of the atomic bomb. |
| March 9, 1942 |
Bush gives Roosevelt an optimistic report on the
possibility of producing a bomb. |
| May 23, 1942 |
The S-1 Executive Committee recommends that the
project move to the pilot plant stage and build one or two piles (reactors)
to produce plutonium and electromagnetic, centrifuge, and gaseous diffusion
plants to produce uranium-235. |
| June 17, 1943 |
President Roosevelt approves the S-1 Executive
Committee recommendation to proceed to the pilot plant stage and instructs
that plant construction to be the responsibility of the Army. |
| August 13, 1942 |
The Manhattan Engineer District is established in
New York City, Colonel James C. Marshall commanding. |
| Aug. 1942 |
Seaborg produces a microscopic sample of pure
plutonium. |
| September 13, 1942 |
The S-1 Executive Committee visits Lawrence's
Berkeley laboratory and recommends building an electromagnetic pilot plant
and a section of a full-scale plant in Tennessee. |
| September 17, 1942 |
Colonel Leslie R. Groves is appointed head of the
Manhattan Engineer District. He is promoted to Brigadier General six days
later. |
| September 19, 1942 |
Groves selects the Oak Ridge, Tennessee site for the
pilot plant. |
| October 3, 1942 |
E. I. du Pont de Nemours and Company agrees to build
the chemical separation plant at Oak Ridge. |
| Fall 1942 |
J. Robert Oppenheimer and the luminaries report from
Berkeley that more fissionable material might be needed than previously
thought. |
| October 19, 1942 |
Groves decides to establish a separate scientific
laboratory to design an atomic bomb. |
| November 12, 1942 |
On the recommendation of Groves and James B. Conant,
the Military Police committee decides to skip the pilot plant stage on the
plutonium, electromagnetic, and gaseous diffusion projects and go directly
from the research stage to industrial-scale production. The Committee also
decides not to build a centrifuge plant. |
| Nov. 1942 |
The Allies invade North Africa. |
| November 25, 1942 |
Groves selects Los Alamos, New Mexico as the bomb
laboratory (codenamed Project Y). Oppenheimer is chosen laboratory director. |
| December 2, 1942 |
Scientists led by Enrico Fermi achieve the first
self-sustained nuclear chain reaction in Chicago. |
| December 10, 1942 |
The Lewis committee compromises on the
electromagnetic method. The Military Police Committee decides to build the
plutonium production facilities at a site other than Oak Ridge. |
| December 28, 1942 |
Roosevelt approves detailed plans for building
production facilities and producing atomic weapons. |
| 1943 |
| January 13 - 14, 1943 |
Plans for the Y-12 electromagnetic plant are
discussed. Groves insists that Y-12's first racetrack be finished by July 1. |
| January 16, 1943 |
Groves selects Hanford, Washington as the site for
the plutonium production facilities. Eventually three reactors, called B, D,
and F, are built at Hanford. |
| February 18, 1943 |
Construction of Y-12 begins at Oak Ridge. |
| February of 1943 |
Groundbreaking for the X-10 plutonium pilot plant
takes place at Oak Ridge. |
| June 1, 1943 |
Site preparation for the K-25 gaseous diffusion
plant commences at Oak Ridge. |
| September 8, 1943 |
Italy surrenders to Allied forces. |
| September 9, 1943 |
Groves decides to double the size of Y-12. |
| September 27, 1943 |
Construction begins on K-25 at Oak Ridge. |
| 1944 |
| Feb. 1944 |
Y-12 sends 200 grams of uranium-235 to Los Alamos. |
| March of 1944 |
The Beta building at Y-12 is completed. |
| March of 1944 |
Bomb models are tested at Los Alamos. |
| June 6, 1944 |
Allied forces launch the Normandy invasion. |
| June 21, 1944 |
Groves orders the construction of the S-50 thermal
diffusion plant at Oak Ridge. |
| July 4, 1944 |
The decision is made to work on a calutron with a
30-beam source for use in Y-12. |
| July of 1944 |
Scientists at the Metallurgical Laboratory issue the
"Prospectus on Nucleonics," concerning the international control of
atomic energy. |
| August 7, 1944 |
Bush briefs General Geroge C. Marshall, informing
him that small implosion bombs might be ready by mid-1945 and that a uranium
bomb will almost certainly be ready by August 1, 1945. |
| September of 1944 |
Colonel Paul Tibbets's 393rd Bombardment Squardron
begins test drops with dummy bombs called pump kins. |
| Summer 1944 - Spring 1945 |
The Manhattan Project's chances for success advance
from doubtful to probable as Oak Ridge and Hanford produce increasing amounts
of fissionable material, and Los Alamos makes progress in chemistry,
metallurgy, and weapon design. |
| 1945 |
| February 2, 1945 |
Los Alamos receives its first plutonium. |
| March of 1945 |
S-50 begins operation at Oak Ridge. |
| March of 1945 |
Tokyo is firebombed, resulting in 100,000
casualties. |
| March 12, 1945 |
K-25 begins production at Oak Ridge. |
| May 7, 1945 |
The German armed forces in Europe surrender to the
Allies. |
| May 23, 1945 |
Tokyo is firebombed again, this time resulting in
83,000 casualties. |
| June 6, 1945 |
Stimson informs President Truman that the Interim
Committee recommends keeping the atomic bomb a secret and using it as soon as
possible without warning. |
| June 14, 1945 |
Groves submits the target selection group's
recommendation to Marshall. |
| July 16, 1945 |
Los Alamos scientists successfully test a plutonium
implosion bomb in the Trinity shot at Alamogordo, New Mexico. |
| July 17 - August 2, 1945 |
Truman, Churchill, and Stalin meet in Potsdam. |
| July 21, 1945 |
Groves sends Stimson a report on the Trinity test. |
| July 24, 1945 |
Stimson again briefs Truman on the Manhattan Project
and peace terms for Japan. In an evening session, Truman informs Stalin that
the U.S. has tested a powerful new weapon. |
| July 25, 1945 |
The 509th Composite Group is ordered to attack Japan
with an atomic bomb "after about" August 3. |
| July 26, 1945 |
Truman, Chinese President Chiang Kai-Shek, and new
British Prime Minister Clement Atlee issue the Potsdam Proclamation, calling
for Japan to surrender unconditionally. |
| Juy 29, 1945 |
The Japanese reject the Potsdam Proclamation. |
| August 6, 1945 |
The gun model uranium bomb, called Little Boy, is
dropped on Hiroshima. Truman announces the raid to the American people. |
| August 8, 1945 |
Russia declares war on Japan and invades Manchuria. |
| August 9, 1945 |
The implosion model plutonium bomb, called Fat Man,
is dropped on Nagasaki. |
| August 14, 1945 |
Japan surrenders. |
| September 2, 1945 |
The Japanese sign articles of surrender aboard the
U.S.S. Missouri. |
| September 9, 1945 |
S-50 shuts down. |
| September of 1945 |
Y-12 shutdown begins. |
| 1947 |
| August of 1947 |
The Manhattan Engineer District is abolished. |
| 1949 |
| March 19, 1949 |
The gates are opened at Oak Ridge, and the public is
permitted to come and go without being badged. |
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