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See also Germany and weapons of mass destruction

The German nuclear energy project was an endeavor by scientists during World War II in Nazi Germany to develop nuclear energy and an atomic bomb for practical use. Unlike the competing Allied effort to develop a nuclear weapon the German effort resulted in two rival teams, one working for the military, the second, a civilian effort co-ordinated by the Reichspost.

Contents 1 Overview 2 Effectiveness and implications 3 Post war 4 Heisenberg's 1941 meeting with Bohr 5 Battle of Berlin 6 Analysis and legacy 7 See also 8 References 9 Further reading 10 Footnotes

The nuclear research effort most widely discussed was that of the Kaiser Wilhelm Institute team led by the physicist Werner Heisenberg. The second was a military team under the scientific leadership of Prof. Kurt Diebner. This military team was also associated with Dr. Paul Harteck who helped to develop the gaseous uranium centrifuge invented by Dr. Erich Bagge in 1942. Their team was part of the German Army (Heereswaffenamt Forschungsstelle E), the Kriegsmarine (navy) had a subsidiary team looking at nuclear propulsion for U-boats under Dr. Otto Haxel. Konteradmiral Karl Witzell and Konteradmiral Wilhelm Rein were military leaders of the naval nuclear project.

The intentions of Heisenberg's team are a matter of historical controversy, centering on whether or not the scientists involved were genuinely attempting to build an atomic bomb for Nazi dictator Adolf Hitler. The project was not a military success by any measure.

A heavy water nuclear test reactor was built in a cave in Haigerloch. This reactor never reached critical condition, because the amount of uranium was never sufficient. The cave is now a museum.^[1]

Nuclear fission was discovered in Germany in 1938-1939 through the work of Otto Hahn, Fritz Strassmen, Lise Meitner, and Otto Robert Frisch (following up on work done by Enrico Fermi). By the beginning of World War II the scientific community was well aware of the early German lead in this area of nuclear physics.

The threat of a Nazi atomic bomb was one of the primary driving forces behind the creation of the British Tube Alloys project which would eventually lead to the Allied nuclear weapons effort: the Manhattan Project. Several European exiles from Germany, Italy, Hungary and other nations eventually would make significant contributions to the Allied nuclear effort. The German government never did finance a full crash program to develop weapons, as they estimated it could not be completed in time for use in the war, thus the German program was much more limited in capacity and ability when compared to the eventual size and priority of the Manhattan Project.

In 1945, a U.S. investigation called Project Alsos determined that German scientists under Heisenberg were close, but still short, of the point that Allied scientists had reached in 1942, the creation of a sustained nuclear chain reaction, a crucial step for creating a nuclear reactor (which in turn could be used for either peaceful purposes, or for creating plutonium, needed for nuclear weapons). The U-234 submarine tried to deliver uranium and advanced weapons technology to Japan, but after the German capitulation, it surrendered to the U.S. before reaching Japan.

There has been a historical debate, however, as to whether the German scientists purposefully sabotaged the project by under-representing their chances at success, or whether their estimates were based in either error or inadequacy.

After the war, ten German scientists: Erich Bagge, Kurt Diebner, Walther Gerlach, Paul Harteck, Horst Korsching, Carl Friedrich von Weizsäcker, Karl Wirtz, Werner Heisenberg, Otto Hahn (who had co-discovered nuclear fission), and Max von Laue (an ardent anti-Nazi), were taken captive by Allied forces and put under secret watch at Farm Hall, England, as part of Operation Epsilon. Their conversations were recorded as Allied analysts attempted to discover the extent of German knowledge about nuclear weapons. The results were inconclusive, but they allowed them to hear the results of the atomic bombing of Hiroshima, Japan, which sent Hahn into a near-suicidal despair. By the next morning, Heisenberg claimed to have worked out exactly how the American atomic bomb must have worked, judging from reports of the damage and explosive size, and gave a lecture to the rest of the captive scientists on the effort.

While it is clear that Heisenberg had a firm understanding of the principles involved, he, either conciously or erroneously, greatly overestimated the amount of fissionable material required by several orders of magnitude.

In September of 1941, Werner Heisenberg met with his former mentor Niels Bohr in occupied Denmark and had a conversation outside of any other witnesses. The exact content of their conversation has, since the 1950s, been a matter of some controversy. The meeting and its controversy was the subject of a Tony Award-winning play from 1998 by Michael Frayn, Copenhagen.

There is considerable speculation on what occurred at the real-life meeting, and the actual accounts of it from the parties involved differ. The pro-Bohr version of the story asserts that Heisenberg was seeking to recruit Bohr to the Nazi nuclear effort, and offering him academic advancement in return. The pro-Heisenberg version asserts that Heisenberg was attempting to give Bohr information about the state of the German atomic programme, in the hope that he might pass it to the Allies through clandestine contacts. At that point the German atomic programme was not progressing well (the Nazi government had decided not to undertake the investment required to develop a weapon during the war); Heisenberg may have suspected that the Allies had a viable atomic program, and hoped that by disabusing them of the idea that the German program was also successful he could dissuade the Allies from using an atom bomb on Germany.

Much of the initial "controversy" resulted from a 1956 letter Heisenberg sent to the journalist Robert Jungk after reading the German edition of Jungk's book Brighter than a Thousand Suns (1956). In the letter, Heisenberg described his role in the German bomb project. Jungk published an excerpt from the letter in the Danish edition of the book in 1956 which, out of context, made it look as if Heisenberg was claiming to have purposely derailed the German bomb project on moral grounds. (The letter's whole text shows Heisenberg was careful not to claim this.) Bohr was outraged after reading this excerpt in his copy of the book, feeling that this was false and that the 1941 meeting had proven to him that Heisenberg was quite happy with producing nuclear weapons for Germany.

After the play inspired numerous scholarly and media debates over the 1941 meeting, the Niels Bohr Archive in Copenhagen released to the public all heretofore sealed documents related to the meeting, a move intended mostly to settle historical arguments over what they contained. Among the documents were the original drafts of letters Bohr wrote to Heisenberg in 1957 about Jungk's book and other topics. The documents added little to the historical record but were interpreted by the media as supporting the "Bohr" version of the events. According to the archivists, the letters were released "to avoid undue speculation about the contents of the draft letter", which had been known about but not been open to historians previously.

Although the motives of the meeting will continue to be debated, several aspects of the meeting cannot be denied. By September of 1941, Germany had been at war for two years, and as Heisenberg was the head of the secret German atomic bomb project, he was risking severe punishment by just speaking to Bohr. Since Bohr was half-Jewish he would never have been allowed to participate in the project. Also, since Bohr was a famous physicist, it would have been fairly easy to conclude that Bohr would be attempting to escape to the West soon, making Heisenberg's meeting with him an even more serious breach of security.

According to the military historian Antony Beevor possession of as much of the German nuclear energy project was a primary motive for Stalin authorising the launching of the Battle for Berlin.^[2] The pre-emptive destruction of as much of this infrastructure was the motive behind the raid on 15 March 1945 by the USAAF Eighth Air Force on the German atomic energy research facility in Oranienburg, a suburb of Berlin, was to keep it from falling intact into Soviet hands.^[3]

There have been numerous other cited factors for the failure of the German program. One is that the repressive policies under Hitler encouraged many top scientists to flee Europe, including many who worked on the Allied project (Heisenberg himself was a target of party propaganda for some time during the Deutsche Physik movement). Another, put forth by Alsos scientific head Samuel Goudsmit, was that the stifling, utilitarian political atmosphere adversely affected the quality of the science done. Another is that the German homeland was nowhere as secure from air attack as was the USA. Had the many massive centralized factories and production facilities constructed for the US bomb project been built in Germany, they would have been prime targets for Allied bombing raids.

In 2005, Berlin historian Rainer Karlsch published a book, Hitlers Bombe (in German), which was reported in the press as claiming to provide evidence that Nazi Germany had tested crude nuclear weapons on Rügen island and near Ohrdruf, Thuringia, killing many war prisoners under the supervision of the SS. Some press reports, however, have reported the book as only having claimed to provide evidence that the Nazis have been successful with a radiological weapon (a "dirty bomb"), not a "true" nuclear weapon powered by nuclear fission. Karlsch's primary evidence, according to his publisher's reports, are "vouchers" for the "tests" and a patent for a plutonium weapon from 1941. Karlsch cites a witness to the Ohrdruf blast and another to the scorched bodies of victims afterwards. He also claims to have radioactive samples of soil from the sites. At the Nuremberg trials in 1946 Nazi munitions minister Albert Speer was questioned by prosecutors about the Ordruf blast, in an attempt to hold Speer accountable for its victims.

Mainstream American historians have expressed skepticism towards any claims that Nazi Germany was in any way close to success at producing a true nuclear weapon, citing the copious amounts of evidence which seem to indicate the contrary. Others counter that Prof. Kurt Diebner had a project which was far more advanced than that of Dr. Werner Heisenberg. A recent article in Physics Today by the respected American historian Mark Walker has presented some of Karlsch's less controversial claims—that the Germans had done research on fusion, that they were aware that a bomb could potentially be made with plutonium, that they had engaged in some sort of test of some sort of device, that a patent on a plutonium device (of unspecified detail) had been filed and found—as substantiated.

The Germans’ only source of heavy water, a necessary component of some of their bomb research, was Norsk Hydro's plant in Vemork, Norway. In February 1943, a Norwegian Commando unit sabotaged the plant. The plant was later bombed from the air and a shipment of heavy water was destroyed in transit. Whether this affected the German program is not clear.

An important footnote to the German nuclear effort is that as part of the Paris Treaties of 1955 and Adenauer's "non-nuclear pledge", Germany has perpetually forsworn nuclear (as well as chemical and biological) weapons. It was this pledge that ultimately cleared the way for West Germany's entry into NATO.

• Copenhagen (play)
• Hans Geiger re the fictitious Uranverein (Uranium Club)
• History of nuclear weapons
• Japanese atomic program
• List of countries with nuclear weapons
• List of nuclear weapons
• Nuclear weapon
• Soviet atomic bomb project
• Zippe-type centrifuge

• Walker M. (2002). "Amerikas Einschätzung der deutschen Atomforschung". Physik in unserer Zeit 33: 167-171. 

• Jeremy Bernstein and David Cassidy, Hitler's Uranium Club: The Secret Recordings at Farm Hall (2001).
• Charles Frank, ed. Operation Epsilon: the Farm Hall transcripts (1993).
• Samuel Goudsmit, ALSOS: The failure of German science (1947).
• Rainer Karlsch, Hitlers Bombe (Munich: DVA, 2005).
• Thomas Powers, Heisenberg's War: The Secret History of the German Bomb (Knopf, 1993).
• Paul Lawrence Rose, Heisenberg and the Nazi Atomic Bomb Project: A Study in German Culture (Berkeley: University of California Press, 1998).
• Michael Schaaf, Heisenberg, Hitler und die Bombe. Gespraeche mit Zeitzeugen (Berlin, GNT-Verlag, 2001) ISBN 3-928186-60-4
• Mark Walker, German National Socialism and the Quest for Nuclear Power, 1939-1949 (London: Cambridge University Press, 1990).
• Mark Walker, Nazi science: Myth, truth, and the German atomic bomb (New York: Plenum Press, 1995).
• GlobalSecurity.org - German Special Weapons
• "New light on Hitler's bomb". New historical information, June 2005: This information not yet integrated into this Wikipedia article.
• Niels Bohr Institute: Release of documents from Niels Bohrs family regarding the 1941 meeting between Bohr and Heisenberg
• Affidavit of German POW Hans Zinsser regarding alleged German nuclear test in October 1944.