The Timeline for the German Nuclear Research Program During World War 2  
  Tuesday, December 29, 1931  
  Harold C. Urey announced the discovery of heavy water at the Christmas meeting of the American. Association for the Advancement of Science. The American physical chemist found that heavy water was highly enriched in the hydrogen isotope deuterium (2H), and was used in many applications such as nuclear magnetic resonance, neutron moderation in nuclear power plants, and organic chemistry as well as German research in creating an atomic weapon.  
  Saturday, December 17, 1938  
  On the evidence of a decisive experiment (the celebrated "radium-barium-mesothorium-fractionation",) German chemist Otto Hahn concluded that the uranium nucleus had "burst" into atomic nuclei of medium weight. This was the discovery of nuclear fission.  
  Thursday, December 22, 1938  
  German chemists Otto Hahn and Fritz Strassmann sent a manuscript to Naturwissenschaften reporting their radiochemical results, which were the irrefutable proof that the uranium had been split into fragments consisting of lighter elements. Simultaneously, they communicated these results to Austrian-born Jewish physicist Lise Meitner, who had escaped out of Germany earlier that year and was then in Sweden. Meitner, and her nephew, Austrian-British physicist Otto Robert Frisch, correctly interpreted these results as being nuclear fission, a term coined by Frisch, which subsequently became internationally known.  
  Friday, January 6, 1939  
  The scientific journal Naturwissenschaften published the findings of Hahn and Strassmann, nuclear physicists at the Kaiser Wilhelm Gesellschaft (Kaiser Wilhelm Society) in Berlin. Their paper reported the proof of nuclear fission using uranium-235.  
  Friday, January 13, 1939  
  Austrian-British physicist Otto Robert Frisch experimentally confirmed the results Hahn and Strassmann experiments as being nuclear fission.  
  Saturday, April 22, 1939  
  After hearing a colloquium paper by German experimental physicist Wilhelm Hanle on the use of uranium fission in a Uranmaschine (uranium machine, i.e., nuclear reactor), German theoretical physicist Georg Joos, along with Hanle, notified Wilhelm Dames at the Reich Ministry of Education of the potential military applications of nuclear energy. This communication would be given to Abraham Esau, head of the physics section of the Reich Research Council at the Reich Ministry of Education.  
  Monday, April 24, 1939  
  German physical chemist Dr. Paul Harteck, director of the physical chemistry department at the University of Hamburg and an advisor to the German Army Weapons Bureau and his teaching assistant German physical chemist Dr. Wilhelm Groth made contact with the Reich Ministry of War to alert them to the potential of military applications of nuclear chain reactions and point out its political significance.  
  Saturday, April 29, 1939  
  A group organized by Abraham Esau, head of the physics section of the Reich Research Council at the Reich Ministry of Education, met to discuss the potential of a sustained nuclear chain reaction. The group included the physicists Walther Bothe, Robert Döpel, Hans Geiger, Wolfgang Gentner, Wilhelm Hanle, Gerhard Hoffmann, and Georg Joos. After this meeting, informal work began at the Georg-August University of Göttingen by Joos, Hanle, and their colleague Reinhold Mannfopff. This group of three physicists was known informally as the first Uranverein (Uranium Club.). The group’s work was discontinued in August 1939, when the three were called to military training.  
  Saturday, September 16, 1939  
  The second Uranium Club first met at a conference organized by German nuclear physicist Dr. Kurt Diebner, advisor to the German Army Weapons Bureau, and his assistant Dr. Erich Bagge. At this conference Diebner presented evidence that U.S. physicists had begun research into uranium chain reaction, specifically citing the recent paper by Niels Borh and John Wheeler "The Mechanism of Nuclear Fission", just published in the September issue of Physics Review. These physicists knew that U235 was capable of slow-neutron fission. The physicists also knew the hurdles of isotope separation, which would make the development of a U235 weapon difficult.  
  Tuesday, September 26, 1939  
  A second meeting of the second Uranium Club was held. This conference was attended by German theoretical physicist Dr. Werner Heisenberg and Paul Harteck. Harteck had experience with heavy water, and argued that the chain reaction pile test be conducted with heavy water as the moderator. Heisenberg argued the atomic pile needed layering of the uranium and the moderator, in order to avoid the neutron capture resonance of U238. The second conference left Heisenberg in charge of the team responsible for theoretical investigation, with Diebner and Bagge responsible for the experimental program. The fission program would be headquartered in the new Kaiser Wilhelm Institute of Physics in Berlin-Dahlem. Fission research was made a secret of the state and publication of scientific results was suppressed.  
  Wednesday, December 6, 1939  
  German physicist Werner Heisenberg submitted the first part of a report to German Army Weapons Bureau, concluding that the surest way to a reactor for energy production is enrichment of U235 in uranium, also the only method of producing explosives "several orders of magnitude more powerful than the strongest explosives yet known."  
  January, 1940  
  The first ton of highly purified uranium oxide was delivered to the German Army Weapons Bureau by the Auer Company.  
  Friday, May 3, 1940  
  German troops in Norway seized control of the world's only heavy water production facility. The Germans would step up production to supply the German fission program.  
  Monday, June 3, 1940  
  Harteck failed to observe neutron multiplication with his uranium oxide-dry ice reactor In Hamburg. His 185 kilograms of uranium were inadequate and Heisenberg's group in Dahlem refused to share more of the available uranium.  
  Wednesday, July 17, 1940  
  In a secret report to the German Army Weapons Bureau German physicist Baron Carl Friedrich von Weizsacker proposed that reactors can be used to create neptunium for the construction of atomic bombs.  
  October, 1940  
  A new fission-research laboratory was completed at the Kaiser Wilhelm Institute. Heisenberg would begin commuting between reactor experiments in Berlin and Leipzig.  
  March, 1941  
  Heisenberg and the Berlin-Dahlem team reported on their first reactor experiments with layers of uranium oxide and paraffin in a cylindrical tank. The results were negative, and Heisenberg concluded that heavy water must be used.  
  September, 1941  
  During the week of September 15-21 Heisenberg met with Danish physicist Dr. Niels Bohr in Nazi-occupied Copenhagen and brought up nuclear fission research. Heisenberg later described the meeting as an attempt to seek advice while Bohr saw it as a hostile approach. Heisenberg and von Weizsacker were in Copenhagen to lecture at a Nazi propaganda institute.  
  December, 1941  
  In early December, the head of the German Army Weapons Research ordered a review of the uranium project. Declaring the army could no longer support projects that would not yield results in the foreseeable future, he considered cancellation of support for fission research.  
  January, 1942  
  Heisenberg and collaborators reported to the German Army Weapons Bureau on reactor experiment B-III. Still without heavy water, the reactor used paraffin and uranium powder and produced no neutron multiplication.  
  Thursday, February 26, 1942  
  A special meeting on nuclear physics was convened by the Reich Research Council. The intent of the meeting was to explain in simple terms to various high ranking officials of the government, including Minister of Armaments Albert Speer, Field Marshal Wilhelm Keitel, head of the OKW (High Command of the Armed Forces), Reichsführer SS Heinrich Himmler, and Reichsmarschall Hermann W. Göring, the necessity for government support of nuclear physics. The first talk on the day's program was "Nuclear Physics as Weaponry." German theoretical physicist Werner Heisenberg spoke later on the theory of extracting energy from nuclear fission, and mentioned the explosive properties of uranium-235.  
  March, 1942  
  Minister of Armaments Albert Speer placed the German economy on a war footing. Projects that did not promise short-term results, including nuclear research, were eliminated or down-graded in priority.  
  April, 1942  
  The Leipzig L-IV reactor demonstrated neutron generation of 13 percent. German theoretical physicist Dr. Werner Heisenberg predicted this design could be critical with 5 metric tons of heavy water and 10 tons of solid uranium metal.  
  Thursday, June 4, 1942  
  A secret meeting was held in Dahlem including Speer, leading nuclear scientists, production and other senior officials. Heisenberg told Speer that a bomb could not be built before 1945, and would require significant monetary and manpower resources. Speer would approve all the scientists' requests, including a bomb-resistant bunker for a large reactor, but the project received the lowest priority that allowed it to proceed.  
  Tuesday, June 9, 1942  
  German Chancellor Adolf Hitler issued a decree for the reorganization of the Reich Research Council as a separate legal entity under the Reich Ministry for Armament and Ammunition. The decree appointed Reich Marshall Goering as its president.  
  Tuesday, June 23, 1942  
  Air leaked into the Leipzig L-IV atomic pile during an inspection for a possible heavy water leak. The burning uranium boiled the water jacket, generating enough steam pressure to blow the reactor apart. Burning uranium powder scattered throughout the lab causing a larger fire at the facility. Heisenberg would leave permanently for Berlin and reactor research in Leipzig ceased.  
  Wednesday, July 1, 1942  
  Heisenberg became acting head of the Kaiser Wilhelm Institute for Physics in Dahlem. He began planning a series of large reactor experiments involving as much of Germany's uranium and heavy water as possible. The uranium metal plates of his design proved difficult to manufacture as well as ineffective. During this time he turned to other research.  
  Click here for information on the American Atomic Program  

The objective of is to provide a day by day account of the events that lead up to and were part of the greatest conflict known to mankind. There are accounts for the activities of each particular day and timelines for subjects and personalities. It is the of this website intent to provide an unbiased account of the war. Analysis, effects caused by an event, or prior or subsequent pertinent events are presented separately and indicated as text that is italicized.

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