German nuclear program during World War II
undertook several research programs relating to nuclear technology, including nuclear weapons and nuclear reactors, before and during World War II. These were variously called Uranverein or Uranprojekt. The first effort started in April 1939, just months after the discovery of nuclear fission in Berlin in December 1938, but ended shortly ahead of the September 1939 German invasion of Poland, for which many German physicists were drafted into the Wehrmacht. A second effort under the administrative purview of the Wehrmacht's Waffenamt began on September 1, 1939, the day of the invasion of Poland. The program eventually expanded into three main efforts: Uranmaschine development, uranium and heavy water production, and uranium isotope separation. Eventually, the German military determined that nuclear fission would not contribute significantly to the war, and in January 1942 the Heereswaffenamt turned the program over to the Reich Research Council while continuing to fund the activity.
The program was split up among nine major institutes where the directors dominated research and set their own objectives. Subsequently, the number of scientists working on applied nuclear fission began to diminish as many researchers applied their talents to more pressing wartime demands. The most influential people in the Uranverein included Kurt Diebner, Abraham Esau, Walther Gerlach, and Erich Schumann. Schumann was one of the most powerful and influential physicists in Germany. Diebner, throughout the life of the nuclear weapon project, had more control over nuclear fission research than did Walther Bothe, Klaus Clusius, Otto Hahn, Paul Harteck, or Werner Heisenberg. Esau was appointed as Reichsmarschall Hermann Göring's plenipotentiary for nuclear physics research in December 1942, and was succeeded by Walther Gerlach after he resigned in December 1943.
Politicization of German academia under the Nazi regime of 1933–1945 had driven many physicists, engineers, and mathematicians out of Germany as early as 1933. Those of Jewish heritage who did not leave were quickly purged, further thinning the ranks of researchers. The politicization of the universities, along with German armed forces demands for more manpower, substantially reduced the number of able German physicists.
Developments took place in several phases, but in the words of historian Mark Walker, it ultimately became "frozen at the laboratory level" with the "modest goal" to "build a nuclear reactor which could sustain a nuclear fission chain reaction for a significant amount of time and to achieve the complete separation of at least tiny amounts of the uranium isotopes". The scholarly consensus is that it failed to achieve these goals, and that despite fears at the time, the Germans had never been close to producing nuclear weapons. The final attempt at constructing a reactor, the 1945 Haigerloch research reactor, did not achieve criticality. With the war in Europe ending in early 1945, various Allied powers competed with each other to obtain surviving components of the German nuclear industry, as they did with the pioneering V-2 SRBM program. The Western Allied effort was the Alsos Mission and the Soviet effort was Russian Alsos. Due to the success of the Manhattan Project, the Western Allies prioritized denying Germany nuclear scientists and resources to the nascent Soviet atomic bomb project.
Discovery of nuclear fission
In December 1938, German chemist Otto Hahn and his assistant Fritz Strassmann sent a manuscript to the German science journal Naturwissenschaften reporting that they had detected and identified the element barium after bombarding uranium with neutrons. Their article was published on 6 January 1939. On 19 December 1938, eighteen days before the publication, Otto Hahn communicated these results and his conclusion of a bursting of the uranium nucleus in a letter to his colleague and friend Lise Meitner, who had fled Germany in July to the Netherlands and then to Sweden. Meitner and her nephew Otto Robert Frisch confirmed Hahn's conclusion of a bursting and correctly interpreted the results as "nuclear fission" – a term coined by Frisch. Frisch confirmed this experimentally on 13 January 1939.First ''Uranverein'' and other early 1939 efforts
On 22 April 1939, after hearing a colloquium paper by his colleague Wilhelm Hanle at the University of Göttingen proposing the use of uranium fission in an Uranmaschine, Georg Joos, along with Hanle, notified Wilhelm Dames, at the Reichserziehungsministerium, of potential military and economic applications of nuclear energy. Abraham Esau, a physicist at the Reich Research Council of the REM, organized a meeting for what become informally known as a Uranverein. The group included the physicists Walther Bothe, Robert Döpel, Hans Geiger, Wolfgang Gentner, Wilhelm Hanle, Gerhard Hoffmann, and Georg Joos; Peter Debye was invited, but he did not attend. After this, informal work began at the Georg-August University of Göttingen by Joos, Hanle, and their colleague Reinhold Mannkopff. Formally the group of physicists was known as the Arbeitsgemeinschaft für Kernphysik. This initial work at Göttingen lasted until the fall of 1939, when Joos and Hanle were drafted into other military research.Independently of this effort, Paul Harteck, director of the physical chemistry department at the University of Hamburg and an advisor to the Heereswaffenamt, and his teaching assistant Wilhelm Groth wrote a letter on 24 April 1939 to Army Ordnance which also mentioned the military application of nuclear chain reactions. Harteck would not receive a reply until August 1939, however, as part of the second Uranverein.
Also independently of the first Uranverein, Nikolaus Riehl, the head of the scientific headquarters at Auergesellschaft, a German industrial firm, read a June 1939 paper by Siegfried Flügge, on the technical use of nuclear energy from uranium. As Auer had a substantial amount of uranium on hand as a waste product from the process of extracting radium, Riehl recognized the possibility of uranium production as a business opportunity for the company, and July 1939 contacted the Army Ordnance Office on the matter. Army Ordnance eventually provided an order for the production of uranium oxide, which took place in the Auer plant in Oranienburg, north of Berlin.
These three efforts, as noted, were independent and lasted until the fall of 1939, when the outbreak of World War II disrupted the work at Göttingen, and also prompted the HWA to take over the work from the Reich Research Council. After the fact, this early work was designated as the first Uranverein, with the HWA's reorganized project being designated the second Uranverein.
Second ''Uranverein''
In August 1939, just before the German invasion of Poland precipitated the formal start of World War II, the Army Ordnance Office moved to take over the work of the Reichsforschungsrat of the Reich Education Ministry, and ordered the RFR to halt all experiments and work on nuclear energy. Esau protested that the discovery of nuclear fission was too recent to warrant such an action, but was ignored. These actions were initiated by the physicist Kurt Diebner, an advisor to the HWA, in association with Erich Bagge. In September 1939, Diebner organized a meeting in Berlin on 16 September.The invitees to this meeting included Walther Bothe, Siegfried Flügge, Hans Geiger, Otto Hahn, Paul Harteck, Gerhard Hoffmann, Josef Mattauch, and Georg Stetter. Its purpose, as Bagge later recalled, was
This group, like the one before it, referred to itself informally as a Uranverein. A second meeting was held soon thereafter, and included Klaus Clusius, Robert Döpel, Werner Heisenberg, and Carl Friedrich von Weizsäcker. Also at this time, the Kaiser-Wilhelm Institut für Physik, in Berlin-Dahlem, was placed under HWA authority, with Diebner as the administrative director, and the military control of the nuclear research commenced. Although the official slogan of the government was "We must make use of physics for warfare", Heisenberg and his colleagues decided that they should instead "make use of warfare for physics".
Heisenberg said that in 1939, the physicists at this second meeting concluded that "in principle atomic bombs could be made, but they also emphasized that it would take a number of years", certainly not less than five. He also said that he "didn't report it to the Führer until two weeks later and very casually because I did not want the Führer to get so interested that he would order great efforts immediately to make the atomic bomb. Speer felt it was better that the whole thing should be dropped and the Führer also reacted that way." He said they presented the matter in this way for their own personal safety, as the probability of success was nearly zero, and that if many thousands of people working on an expensive and time-consuming project ended up developing nothing, there could be "extremely disagreeable consequences" for them. Luftwaffe ''Generalfeldmarschall Erhard Milch asked how long America might take to develop a nuclear weapon, and was given an estimate of 1944, though the group, among themselves, "believed that they would not be able to make atomic bombs before three or four years."
When it was apparent that the nuclear weapon project would not make a decisive contribution to ending the war in the near term, control of the KWIP was returned in January 1942 to its umbrella organization, the Kaiser-Wilhelm Gesellschaft. HWA control of the project was subsequently passed to the RFR in July 1942. The nuclear weapon project thereafter maintained its kriegswichtig designation, and funding continued from the military, but it was then split into the areas of uranium and heavy water production, uranium isotope separation, and the Uranmaschine. It was in effect broken up between institutes where the different directors dominated the research and set their own research agendas. The dominant personnel, facilities, and areas of research were:
- Walther BotheDirector of the
On 4 June 1942, a conference regarding the project, initiated by Albert Speer as head of the "Reich Ministry for Armament and Ammunition", decided on its continuation merely for the aim of energy production. On 9 June 1942, Adolf Hitler issued a decree for the reorganization of the RFR as a separate legal entity under the RMBM; the decree appointed Reich Marshal Hermann Göring as its president. The reorganization was done under the initiative of Minister Albert Speer of the RMBM; it was necessary as the RFR under Bernhard Rust the Minister of Science, Education and National Culture was ineffective and was not achieving its purpose. The hope was that Göring would manage the RFR with the same discipline and efficiency as he had the aviation sector. A meeting was held on 6 July 1942 to discuss the function of the RFR and set its agenda. The meeting was a turning point in Nazi attitudes towards science, as well as recognition that the policies which drove Jewish scientists out of Germany were a mistake, as the Reich needed their expertise. Abraham Esau was appointed on 8 December 1942 as Hermann Göring's Bevollmächtigter for nuclear physics research under the RFR; in December 1943, Esau was replaced by Walther Gerlach. In the final analysis, placing the RFR under Göring's administrative control had little effect on the German nuclear weapon project.
Speer states that the project to develop the atom bomb was scuttled in the autumn of 1942. Though the scientific solution was there, it would have taken all of Germany's production resources to produce a bomb, and then no sooner than 1947. Development did continue with a "uranium motor" for the navy and development of a German cyclotron. However, by the summer of 1943, Speer released the remaining 1200 metric tons of uranium stock for the production of solid-core ammunition.
Over time, the HWA and then the RFR controlled the German nuclear weapon project. The most influential people were Kurt Diebner, Abraham Esau, Walther Gerlach, and Erich Schumann. Schumann was one of the most powerful and influential physicists in Germany. He was director of the Physics Department II at the Frederick William University, which was commissioned and funded by the Oberkommando des Heeres to conduct physics research projects. He was also head of the research department of the HWA, assistant secretary of the Science Department of the OKW, and Bevollmächtigter'' for high explosives. Diebner, throughout the life of the nuclear weapon project, had more control over nuclear fission research than did Walther Bothe, Klaus Clusius, Otto Hahn, Paul Harteck, or Werner Heisenberg.