Timeline of The Manhattan Project - 1941

1941

• February 25: Conclusive discovery of plutonium by Glenn Seaborg and Arthur Wahl.
• May 17: A report by Arthur Compton and the National Academy of Sciences is issued which finds favorable the prospects of developing nuclear power production for military use.
• June 28: Roosevelt creates the Office of Scientific Research and Development (OSRD) under Vannevar Bush with the signing of Executive Order 8807. OSRD absorbs NDRC and the Uranium Committee. James B. Conant succeeds Bush as the head of NDRC.
• July 2: The MAUD Committee chooses James Chadwick to write the second (and final) draft of its report on the design and costs of developing a bomb.
• July 15: The MAUD Committee issues final detailed technical report on design and costs to develop a bomb. Advance copy sent to Vannevar Bush who decides to wait for official version before taking any action.
• August: Mark Oliphant travels to USA to urge development of a bomb rather than power production.
• September 3: British Chiefs of Staff Committee approve nuclear weapons project.
• October 3: Official copy of MAUD Report (written by Chadwick) reaches Bush.
• October 9: Bush takes MAUD Report to Roosevelt, who approves Project to confirm MAUD's findings. Roosevelt asks Bush to draft a letter so that the British government could be approached "at the top."
• December 6: Bush holds a meeting to organize an accelerated research project, still managed by Arthur Compton. Harold Urey is assigned to develop research into gaseous diffusion as a uranium enrichment method, while Ernest O. Lawrence is assigned to investigate electromagnetic separation methods. Compton puts the case for plutonium before Bush and Conant.
• December 7: The Japanese attack Pearl Harbor. The United States and Great Britain issue a formal declaration of war against Japan the next day.
• December 11: United States declares war on Germany and Italy.
• December 18: First meeting of the OSRD sponsored S-1 Uranium Committee, dedicated to developing nuclear weapons.