The Manhattan Project Heritage Preservation Association, Inc.

"Preserving, Exhibiting, Interpreting and Teaching the History of the Manhattan Project"

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"In an enterprise such as the building of the atomic bomb the difference between ideas, hopes, suggestions and theoretical calculations, and solid numbers based on measurement, is paramount.  All the committees, the politicking and the plans would have come to naught if a few unpredictable nuclear cross sections had been different from what they were by a factor of two" - Emilio Segre; Los Alamos Physicist


"The Manhattan Engineer District bore no relation to the industrial or social life of our country; it was a separate state, with its own airplanes and its own factories and its thousands of secrets.  It had a peculiar sovereignty, one that could bring about the end, peacefully or violently, of all other sovereignties." - Herbert S. Marks

Please Read Carefully

This is a very complex web site with more than 3,000 pages and more than 2,100 photos.  We do not want you to miss what you are looking for.  

Below is a chronological, detailed narrative history of the Manhattan Project.  At this time it is not complete, but we are adding material on a continuous basis.  

1) IF YOU ARE LOOKING FOR Photographs, Documents, Articles, Personal Remembrances, Letters, etc., then please proceed to our Historical Artifact Center - Section B .

2) IF YOU ARE ONLY INTERESTED IN A SPECIFIC OPERATING UNIT OF THE MANHATTAN PROJECT, such as Los Alamos, Oak Ridge, the 509th Composite Group, then also please proceed to our Historical Artifact Center - Section A.





Please "click" on the appropriate section below.  If you start with the 'Introduction', there are buttons that allow you to move forwards and backwards without returning to the 'Table of Contents' page.


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   1.     Introduction
        a.   Atomic Bomb Timeline - 1920 to Aug. 1942
        b.   Atomic Bomb Timeline - Sep. 1942 to Dec. 1944
        c.   Atomic Bomb Timeline - Jan. 1945 to VJ Day
   2.     The Early Years (1900 – 1939): A Synopsis
        a.   Early Enlightenment
        b.   Shame at Gottingen
        c.   The "Scientific Exodus"
        d.   The "Uranium Confusion"
        e.   Fission
        f.   "Pa! This Requires Action!"
   3.     The Einstein Letter (10/11/39)
   4.     Early Government Support (10/21/39 to 8/13/42)
        a.     The Uranium Committee – 10/21/39
        b.     Isotope Separation Methods
              1.     Electromagnetic
              2.     Gaseous Diffusion
              3.     Centrifuge
              4.     Liquid Thermal Diffusion
        c.     National Defense Research Committee – 6/40
        d.     Office of Scientific Research & Development – 6/28/41
        e.    The MAUD Report - 7/2/41
        f.     Britain to U.S. - "Quit Dragging Your Feet"
        g.     Moving Into Action - "Top Policy Group"
        h.     The Discovery of Element 94 - Plutonium
        i.     Isotope Separation - Continuing Progress - May 1942
        j.     The U.S. Army Corp of Engineers - June 1942
   5.     The Manhattan Engineer District – The Beginning – 8/13/42
        a.     Isotope Separation & Plutonium - Fall 1942
        b.     Berkeley Summer Study Group
        c.     Enter DuPont / Decision Time
        d.     The First Lewis Committee - 11/42
        e.     Formal Approval by F.D.R. - 12/42
        f.     Chicago Metallurgical Laboratory (Met Lab)
   6.     The Manhattan Engineer District – Moving into High Gear – 12/42 to 7/45
        a.     Marshalling the Forces
              1.     Personnel
                   a.     Security - Military Police
                   b.     Civilian Scientific
                   c.     SED -   Special Engineer Detachment (Scientists in Uniform)
                   d.     Support Services
                   e.     Trades – Critical Skills
                   f.     Women
                   g.     Minorities
              2.     University Partners (Research & Development)
              3.     Corporate Partners (Research, Construction & Operational Management
              4.     Military Policy Committee
              5.     Canada's Role
        b.     Clinton Engineer Works (Oak Ridge) – 9/19/42
              1.     Site Selection – 9/19/42
              2.     Y-12 Plant – Electromagnetic Separation – 2/18/43
              3.     K-25 Plant – Gaseous Diffusion Separation – 9/27/43
              4.     X-10 Plant – Graphite Reactor (Semi-Works) – 2/43
              5.     S-50 Plant – Liquid Thermal Diffusion – 9/27/44
        c.     Los Alamos Laboratory – Project Y – 11/25/42
              1.     Why Was Los Alamos Needed?
              2.     J. Robert Oppenheimer Selected as Director
              3.     Site Selection - The Search in the West
              4.     Site Selection - Los Alamos Ranch School
              5.     Site Selection - The Ranch School Closes
              6.     "Buck Rogers" Operation Begins
              7.     Military Laboratory to Academic Outpost
              8.     Oppenheimer and His Staff Arrive
              9.     New Laboratory Forged The Army Way
            10.     Birth of "The Gadget"
            11.     Univ. of Calif. to Operate Lab
            12.     Oversight Committee Formed
            13.     Here's Your Damned Organization Chart
            14.     Plutonium Complicates Early Gun Work
            15.     Research on Spontaneous Fission
            16.     Experimenting With Tanks and Barns
            17.     Implosion is the "Key"
            18.     Evolving From Calculators to Computers
            19.     Trinity - The Completion of the Mission
            20.     Scientists in Uniform - The SED's
        d.     Hanford Engineer Works – Site W – 1/16/43
              1.     Site Selection – 1/16/43
              2.     The "Piles" at Hanford (B, D, & F)
                     a.     Xenon Poisoning
              3.     Chemical Separation Facilities at Hanford
              4.     Chemical Concentration Facilities at Hanford
        e.     Philadelphia Navy Yard – Thermal Diffusion Plant – 1/44
              1.     Naval Research Center – Washington, DC
        f.     ALSOS
              1.     ALSOS I – Italy
              2.     ALSOS II – France
              3.     ALSOS III - Germany
        g.    Niels Bohr's Memorandum to F.D.R. - 7/44
   7.     Putting the “Weapon" to Military Use
        a.     The 509th Composite Group
              1.     Timeline - Inception to Hiroshima Mission
              2.     509th Activation & Organization
              3.     The Planes of the 509th
              4.     Transporting the Components to Tinian
                   a.     Nicholas Del Genio
                   b.     USS Indianapolis
                   c.     The "Green Hornet" Line
              5.     The Mather AFB "Incident"
              6.     Mission to Drop "Leaflets" Over Japan
        b.     The Death of F.D.R. – 4/12/45
        c.     The  of German Submarine U-234
        d.     The Target Committee Report - 5/10-11/1945
        e.     Interim Committee Report – 6/6/45
        f.     The “Franck Report” – 6/45
        g.     Oak Ridge Petition #1 - Mid July 1945
        h.     The Trinity Test - 5/45 to 7/16/45
             1.   The "Dark" Days  
             2.   Preparing for the Test
             3.   Dawn of the Atomic Age – 7/16/45
        i.     Petition to the President - Leo Szilard - 7/17/45
        j.     Choosing the Target
        k.     Potsdam Proclamation – 7/26/45
        l.     Hiroshima Mission – 8/6/45
             1.   Timeline - Hiroshima Mission
             2.    "Little Boy" Uranium Bomb
       m.     Nagasaki Mission – 8/9/45
             1.   Timeline - Nagasaki Mission
             2.    "Fat Man" Plutonium Bomb
   8.     Japan Surrenders – War Ends – 8/14/45
   9.     The Manhattan Project Ends - 12/31/46
  10.    Oppenheimer's Post War Treatment: A National Disgrace
        a.     Holding the Accusers Accountable
        b.     "Snake-in-the-Grass" Awards
  Appendix I - The Lingering Controversy
  Appendix II - Legacy of the Enola Gay
  Appendix III - Scientific Biographies
  Appendix IV - Espionage on the Manhattan Project