Nazi Germany 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 (Uranium Society) or Uranprojekt (Uranium Project). 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 Heereswaffenamt began on September 1, 1939, the day of the invasion of Poland. The program eventually expanded into three main efforts: Uranmaschine (nuclear reactor) 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 (Reichsforschungsrat) 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 Wehrmacht demands for more manpower (many scientists and technical personnel were conscripted, despite possessing technical and engineering skills), 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 (personnel, facilities, and materiel), as they did with the pioneering V-2 short-range ballistic missile 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 German nuclear scientists and resources to the nascent Soviet atomic bomb project.
Nazi Germany 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 (Uranium Society) or Uranprojekt (Uranium Project). 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 Heereswaffenamt began on September 1, 1939, the day of the invasion of Poland. The program eventually expanded into three main efforts: Uranmaschine (nuclear reactor) 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 (Reichsforschungsrat) 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 Wehrmacht demands for more manpower (many scientists and technical personnel were conscripted, despite possessing technical and engineering skills), 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 (personnel, facilities, and materiel), as they did with the pioneering V-2 short-range ballistic missile 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 German 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 ("Natural Sciences") 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 uraniumfission in an Uranmaschine (uranium machine, i.e., nuclear reactor), Georg Joos, along with Hanle, notified Wilhelm Dames, at the Reichserziehungsministerium (REM, Reich Ministry of Education), 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 (Uranium Club). The group included the physicists Walther Bothe, Robert Döpel, Hans Geiger, Wolfgang Gentner (probably sent by Walther Bothe), 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 (Nuclear Physics Association). 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 (HWA, Army Ordnance Office), 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 (usually known as just "Auer"), 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 (Army Ordnance) 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 (HWA) moved to take over the work of the Reichsforschungsrat (RFR, Reich Research Council) of the Reich Education Ministry (REM), 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.
to make all preparations to be able to answer beyond doubt the question of whether generating nuclear energy was feasible. It would certainly be very nice if it were possible to acquire a new source of energy, it would also very probably have military importance; a negative answer would be just as important, since we could be sure that the enemy would also not be able to make use of it.
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 (KWIP, Kaiser Wilhelm Institute for Physics, after World War II the Max Planck Institute for Physics), 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. LuftwaffeGeneralfeldmarschallErhard 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 (the Kaiser Wilhelm Society, after World War II the Max-Planck-Gesellschaft). HWA control of the project was subsequently passed to the RFR in July 1942. The nuclear weapon project thereafter maintained its kriegswichtig (war importance) 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 (uranium machine, i.e., nuclear reactor). 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:
Kurt Diebner – Director of the HWA Versuchsstelle (testing station) in Gottow and of the RFR experimental station in Stadtilm, Thuringia; he was also an advisor to the HWA on nuclear physics.
Measurement of nuclear constants. ca. 6 physicists
Heavy water production and isotope production. 5 physical chemists and physicists
Werner Heisenberg – Director of the Department of Theoretical Physics at the University of Leipzig until summer 1942; thereafter acting director of the Kaiser-Wilhelm-Institut für Physik (Kaiser Wilhelm Institute for Physics), in Berlin-Dahlem.
Uranmaschine, isotope separation, and measurement of nuclear constants. ca. 7 physicists and physical chemists
Transuranic elements and measurement of nuclear constants. ca. 6 physicists and physical chemists
The point in 1942 when the army relinquished control of the project was its zenith in terms of the number of personnel devoted to the effort, and this was no more than about seventy scientists, with about forty devoting more than half their time to nuclear fission research. After this the number diminished dramatically, and many of those not working with the main institutes stopped working on nuclear fission and devoted their efforts to more pressing war related work.
On 4 June 1942, a conference regarding the project, initiated by Albert Speer as head of the "Reich Ministry for Armament and Ammunition" (RMBM: Reichsministerium für Bewaffnung und Munition; after late 1943 the Reich Ministry for Armament and War Production), 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 (plenipotentiary) 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.