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Albert Einstein wrote Franklin D. Roosevelt about the dangerous development of Uranium that could lead to chain reactions and powerful bombs. In October, Roosevelt develops a committee to study the development of Uranium.
http://www.atomicarchive.com/History/mp/chronology.shtml
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John R. Dunning and colleagues discover that fission is much more successful in the rare U-235 rather than the abundant U-238
http://www.atomicarchive.com/History/mp/chronology.shtml
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The Japanese bomb Pearl Harbor. dragging the United States into WWII. Three days later, Italy and Germany declare war on the United States.
http://www.atomicarchive.com/History/mp/chronology.shtml
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Roosevelt approves the plan, proposed by Vannevar Bush, to build an atomic bomb.
http://wmbf.images.worldnow.com/images/18874569_BG1.jpg
http://www.atomicarchive.com/History/mp/chronology.shtml -
The Manahattan Engineer District is established in New York City, starting the Manhattan Project.
http://nuclearweaponarchive.org/Usa/Med/Szilein.jpg
http://www.atomicarchive.com/History/mp/chronology.shtml -
J. Roppert Oppenheimer decides that more fissionable material is needed to make a successful atomic bomb.
http://upload.wikimedia.org/wikipedia/commons/0/03/JROppenheimer-LosAlamos.jpg
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The Military Policy Committee decides to go directly from the research stage to industrial-scale production, while also deciding not to build a centrifuge plant.
http://www.atomicarchive.com/History/mp/Images/SB57.jpg
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Hanford Washington is selected as a plutonium production facility. Three Reactors, B, D, and F are built.
http://www.atomicarchive.com/History/mp/chronology.shtml
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It is realized that three times more fissionable material is needed for a successful atomic bomb than at first thought.
http://www.atomicarchive.com/History/mp/chronology.shtml -
Little Dummy Test Bombs called "Pumpkins" are dropped by Paul Tibbet's 393rd Bombardment Squad.
http://upload.wikimedia.org/wikipedia/commons/1/17/Pumpkin_bomb.jpg
http://www.atomicarchive.com/History/mp/chronology.shtml -
The Manhattan Plan is changed from doubtful to probable as Hanford and Oak ridge produce more fissionable material and Los Alamos, New Mexico makes advances in chemistry
http://www.atomicarchive.com/History/mp/chronology.shtml
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Franklin D. Roosevelt dies and Truman is quickly informed about the nuclear plan, but is told to keep it secret.
http://www.atomicarchive.com/History/mp/chronology.shtml
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The idea for demonstrating the atomic bomb before it is detonated in combat is shot down by the Interim Committee
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The United States detonates its first atomic bomb near Alamogordo, New Mexico. The bomb explodes with a force eqivalent to 18,000 tons of TNT.
http://www.pbs.org/wgbh/amex/bomb/timeline/index.html?utm_source=Facebook&utm_medium=pbsofficial&utm_campaign=thisdayhistory
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The Japanese refuse to surrender, even when the United States has warned Stalin about their new dangerous weapon.
http://withfriendship.com/images/h/36859/the-potsdam-declaration-called.jpg
http://www.atomicarchive.com/History/mp/chronology.shtml -
The "Little Boy" atomic bomb was dropped 1,900 feet above Hiroshima, killing 140,000 people with 12.500 tons of TNT.
http://www.pbs.org/wgbh/amex/bomb/timeline/index.html?utm_source=Facebook&utm_medium=pbsofficial&utm_campaign=thisdayhistory' >American Experience</a>
http://www.english.illinois.edu/maps/poets/g_l/levine/bombing.htm -
The "Fat Man" atomic bomb is dropped 1,900 feet above Nagaski, killing 70,000 with 22,000 pounds of TNT.
http://www.pbs.org/wgbh/amex/bomb/timeline/index.html?utm_source=Facebook&utm_medium=pbsofficial&utm_campaign=thisdayhistory
http://epathram.com/pacha/files/2010/08/nagasaki-fat-man-plutonium-bomb-explosion-epathram.jpg -
Japan formally surrenders, ending a threat to the United States.
http://americanhistory.about.com/library/timelines/bltimelinemanhat.htm -
All atomic energy activities are moved from the Manhattan Engineer District to the United States Atomic Energy Commission, ending the Manhattan Plan.
http://www.atomicarchive.com/History/mp/chronology.shtml -
The Limited Nuclear Test Ban Treaty goes into effect, limiting use of nuclear weapons
http://www.pbs.org/wgbh/amex/bomb/timeline/index.html?utm_source=Facebook&utm_medium=pbsofficial&utm_campaign=thisdayhistory
http://www.jfklibrary.org/~/media/assets/Education and Public Programs/Education/For Teachers Manual Upload/JFKSignsTestBanTreaty.jpg
