Building Hitler's Bomb
German effort to build nuclear weapons in World War II
Anyone who has studied the effort to develop atomic energy in Germany during World War II immediately confronts three questions. Were German scientists trying to make a nuclear weapon? If so, how close did they come to succeeding? And if they had succeeded, would they have turned the weapon over to Hitler? All three questions have been answered in very different ways, but before proceeding to analyze them it is important to clarify what we mean by "German scientists."
In December 1938, the German physical chemists Otto Hahn and Fritz Strassmann became the first to observe the fissioning of atomic nuclei. Bombarding the heavy element uranium with slow neutrons, they expected to come up with a nucleus of comparable mass but instead were mysteriously confronted with end products at least one of which was the relatively light nucleus barium, roughly half the weight of uranium. A month later, the Austrian-born Jewish physicists Lise Meitner and her nephew Otto Frisch--who had taken refuge in Scandinavia--correctly and momentously inferred from the Hahn-Strassmann observation that the uranium nucleus had been split in two. Neither Meitner, who had been a colleague of Hahn's in Berlin, nor Frisch, who had been in Hamburg, can be counted among the "German scientists."
The same goes for Rudolf Peierls, a Jew who had emigrated to England from Germany. It was a 1940 memorandum of Peierls and Frisch (by that time also in England) that persuaded the Allies an atomic bomb was a real possibility. According to Frisch and Peierls, if you could separate a relatively modest amount of the rare uranium isotope U-235 from the common uranium isotope U-238, you could generate an explosive nuclear reaction. Prior to this it was thought that tons would be required--an amount so massive that scientists like Niels Bohr had decided that nuclear weapons were a practical impossibility.
Nor can one count among "German scientists" such physicists as James Franck or Hans Bethe or, needless to say, Albert Einstein, all of them German Jews or Germans of Jewish ancestry and all of them driven from the country in the early 1930's. Or non-Germans like John von Neumann and Eugene Wigner, Hungarian Jews who were beginning their careers in the German university system before they, too, were forced to emigrate. Or Italians like Emilio Segre and Enrico Fermi, compelled to leave Italy because of the German-inspired racial laws. (Segre was a Jew, Fermi's wife was Jewish.)
Even inside Germany itself there were scientists who should not be included in the list. Strassmann himself, an avid anti-Nazi, was deprived of his livelihood during the war. And then there was the Nobelist Max von Laue, who publicly refused to deny Einstein the credit for the theory of relativity, something most other German physicists were all too ready to do. Similarly, there was Gustav Hertz, a physicist of Jewish ancestry who shared the 1925 Nobel Prize with James Franck and whose students and colleagues hid him in the Siemens industrial laboratories in Berlin for the duration of the war.
Finally, there were German scientists with acceptable racial pedigrees but unacceptable academic credentials. One of them was Manfred von Ardenne, an inventor and entrepreneur, who managed to persuade the German post office to sponsor work in nuclear physics on his estate in Berlin. In early 1941, one of his associates, Fritz Houtermans--who had been jailed by both the Soviet secret police and the Gestapo--observed that plutonium (as it came to be called) was an even better nuclear explosive than uranium. (The same discovery had been made independently by the more conventional German physicist C. F. von Weizsäcker and by the American physicist Louis Turner a few months earlier.) Von Ardenne's group also made significant progress in separating the uranium isotopes. While their achievements were more or less ignored by the German scientific establishment, after the war the Russians thought them important enough to ship von Ardenne, his equipment, and his colleagues east, where they helped to make the first Soviet bomb.
Who then is left?
In the fall of 1939, German Army Ordnance decided it was imperative to study nuclear fission for its possible use in weaponry. The military agency took over the Kaiser Wilhelm Institute in Berlin and began drafting physicists and chemists to work on the project. The most important "draftee" was Werner Heisenberg (1901-76), certainly one of the greatest physicists of this century and a man whose prestige in Germany was enormous.
In addition to Heisenberg, some 60 scientists from various institutions eventually joined the project. They came to call themselves the Uranverein, the Uranium Club. Clearly these are the German scientists one wants to consider--they, and the industrial infrastructure that served them. One notorious component of the latter was the Degussa company, which had taken over the Auer metallurgic company--its previous owners had been insufficiently Aryan--and used slave labor to produce uranium oxide for the Uranverein. It, too, should be counted.(*)
We may now return to the three questions. Was the Uranverein, first of all, trying to make a nuclear weapon? There cannot be much dispute about this, at least before early 1942, when the Army withdrew from the initiative. From then on, the project, now funded by the Reich Research Council, focused mostly on making a functioning nuclear reactor. This shift of emphasis enabled the Germans, and their apologists, to claim after the war that the project had really been aimed at the peaceful use of nuclear energy. But the claim was false. Once plutonium was discovered, reactors became weapons, by virtue of the fact that they could be used to manufacture that element. The Uranverein was very explicit about this in appealing to the government for funding. There was also a smaller program to try to design some sort of exploding reactor that--like a miniature Chernobyl--could spread radioactive material over a large area.
So to the first question my answer is yes. But how close were the Germans to their goal? To this the common answer is, not very.
Various explanations have been given for this. One is that Germany was being pressed hard by Allied bombardment. Another is that, war or no war, it lacked the industrial capacity for the job. A third is that the Uranverein was not really trying all that hard, or was even attempting to sabotage the project. My own favored explanation is none of these, but rather simple incompetence.
One must keep in mind that by early December 1942, Enrico Fermi, with an infrastructure certainly no larger than that available to the Uranverein, had succeeded in making the first functioning nuclear reactor in an abandoned squash court at the University of Chicago. This was something the Germans never achieved. The difference is that our program had Fermi while the Germans had Heisenberg. Although his ego prevented him from acknowledging it, Heisenberg was not a good engineer. If the Germans, who started first, had been able to create a self-sustaining chain reaction, the whole project would have taken on a much greater sense of possibility.
Which brings me to the last question: would the scientists have turned the bomb over to Hitler? Here, our own experience may be relevant. Once the Manhattan Project was launched in December 1941, it came under the wing of the United States Army. Scientists were drafted and sent as soldiers to Los Alamos; in the beginning there was even talk of giving them simulated ranks and putting them into uniform. After the bomb was built, the Army took possession of what it had bought and paid for. Although a few of the scientists involved tried to enter into the decision process, they had no say in what finally was done with the device. Can anyone imagine that things would have been different in Germany?
What is remarkable is that today, a half-century after the fact, the activities and intentions of the Uranverein still provoke debate. In 1993 the journalist Thomas Powers, in Heisenberg's War, tried to argue that Heisenberg deliberately sabotaged the German project by withholding knowledge about the bomb and even attempted to pass information about it to the Allies. Powers' book unleashed a hailstorm of protest. Now we have a book-length refutation of it in Heisenberg and the Nazi Atomic Bomb Project by the historian Paul Rose.
How are such radical disagreements possible? After all, we are not trying to reconstruct a prehistoric civilization from a few drawings on the wall of a cave. This was a project that created a paper trail of hundreds and hundreds of documents. The principals were, at least until a few years ago, all alive and prepared to tell their stories. Let me give two examples that will show just how difficult a subject it nevertheless is.
Early in his book, Rose quotes what he refers to as a "bizarre letter," undated but purportedly written in the spring of 1970, from Heisenberg to an American woman named Ruth Nanda Anshen. Anshen was the editor and guiding spirit of a series of books by outstanding thinkers. Two of her authors were Heisenberg and the Columbia physicist I.I. Rabi, both of whom were also on her board of editors. Here is the letter, taken directly from Anshen's own book, Biography of an Idea (1986):
I have finished reading in your "Perspectives in Humanism" series the volume written by Professor Rabi entitled Science: The Center of Culture. I should like to review this important volume. However, I must say to you that I shall have to take exception to Dr. Rabi's statement that "such a tremendous undertaking as Oak Ridge [where much of our work in isotope separation was performed], with huge, combined efforts of science, engineering, industry, and the Army, would have been impossible in bomb-ridden Germany....Dr. Hahn, Dr. von Laue, and I falsified the mathematics in order to avoid the development of the atom bomb by German scientists.
When I read this letter in Rose's book, I found it not "bizarre" but incredible. Heisenberg was always careful not to make explicit claims of this nature. He let others do that for him: principally the journalist Robert Jungk, whose 1958 book, Brighter Than a Thousand Suns, argued that German nuclear physicists had "obeyed the voice of conscience and attempted to prevent the construction of atomic bombs"; and, after Heisenberg's death in 1976, Powers and even his widow made similar assertions. Why then would Heisenberg issue so sweeping a statement in so apparently casual a manner? Why had he not revealed this startling information in any of his own published accounts of his wartime activities? And what does "falsified the mathematics" mean? The atomic bomb did not involve a mathematical equation that one could "falsify," but rather hundreds upon hundreds of engineering details.
And why the mention of Hahn and Laue as his co-conspirators? Hahn was not a mathematician but a physical chemist. While he disliked the Nazis, he did like his creature comforts, and there is no indication he ever risked his life for anything except helping Lise Meitner to escape Germany. (She, for her part, was so infuriated by Hahn's generally laissez-faire attitude toward the Nazis that after the war she wrote him an exceedingly angry letter.) And as for Laue, although he was at the Kaiser Wilhelm Institute, he had nothing to do with the Uranverein, and in any case was not a nuclear physicist. In short, anyone with the slightest awareness of these matters would find Heisenberg's claim about Laue and Hahn totally absurd--as Heisenberg would surely have known.
Rose notes another oddity. Anshen gave her papers, including all her letters, to Columbia University; this document is not among them. Still, Rose thinks it "beyond doubt that the letter was genuine."
Upon reading Rose's book, I decided to check the matter out. My colleague Cathryn Carson, who has studied much of the Heisenberg nachlass, confirmed that she had come across; correspondence between Heisenberg and Anshen, and she approached Helmut Rechenberg, who is in charge of the Heisenberg archive in Munich (and with whom I have strongly disputed Heisenberg's wartime activities), to let me see it. There are in fact three letters.
The first, from Anshen to Heisenberg, is in English and is dated May 30, 1970. In it she requests that Heisenberg write a review of Rabi's book for inclusion in a new series she was editing. Heisenberg replied on June 19 in German. In this letter, a page and a half in length, he asks Anshen to inform Rabi of his reluctance to write the review on account of his disagreements with Chapter 7, on the German atomic-bomb project. He is especially upset that Rabi should have accepted the argument--first put forward by the Dutch-American physicist Samuel Goudsmit in his book, Alsos -- that the Germans would have been only too happy to turn the bomb over to Hitler had they been able to build it.
It is not difficult to understand why Heisenberg should have objected to Rabi's reliance on Goudsmit. The latter had led a mission named "Alsos" -- "grove," in Greek to follow the advancing Allied armies into Germany and capture as many of the Uranverein as possible along with their equipment. In the event, nine members of the "club," including Heisenberg, Hahn, and von Weizsäcker, were interned in England for six months in an estate near Cambridge named Farm Hall. British intelligence had wired the place to record everything the Germans said; the transcripts, which were not released until 1992, form the most vivid record we have of the real thoughts of the Uranverein. Goudsmit clearly had access to them in writing his book, and he and Heisenberg, and later von Weizsäcker, subsequently got into a bitter exchange of letters and articles over his interpretation of what they contained.
The rest of the June 1970 letter to Anshen is Heisenberg at his self-exculpatory best. He constructs some sort of murky parallel: Rabi, he writes, "completely overlooks the fact that the German physicists had about the same kind of psychological attitude toward putting a bomb in Hitler's hand as many Americans have today about the possibility of ending the American war with North Vietnam by dropping a hydrogen bomb on Hanoi." He then ends by asking Anshen to take these matters up with Rabi so that they can avoid a public dispute. There is no mention of Oak Ridge or the Allied bombing of Germany; no mention of falsifying data; no mention of Hahn and Laue.
On July 9, Anshen replied, saying that she had spoken to Rabi and had decided it might be better if Heisenberg did not review his book after all. She writes: "Professor Rabi would not wish to enter into a polemical discussion with so great a physicist as you are." Knowing Rabi as I did, I can just see him concocting this phrase--"so great a physicist as you are"--with some glee. Rabi knew his man. He had offered Heisenberg a job at Columbia in 1939, on Heisenberg's last visit to America just before the war. As Rabi later told me, Heisenberg turned him down on the grounds that he did not want to lose his tenure in the German university system.
What should we make of all this? Unless and until someone comes up with the original of the letter that Rose quotes from Anshen's book, I shall regard it as a chimera.
Now for the second example of how difficult it is to determine Heisenberg's role. This is a more complicated story, and I have to take a certain responsibility for it. Beginning in November 1977, on and off for two years, I conducted a series of tape-recorded interviews with Hans Bethe that ultimately led to a three-part New Yorker profile. During the war, Bethe (who arrived in this country in 1935) had been the head of the theoretical division at Los Alamos and therefore in the inner circle of J. Robert Oppenheimer and his advisers. In the course of our conversations I asked him whether, while working on the bomb, the scientists at Los Alamos knew about the status of the German nuclear project. Such intelligence would have been a closely held secret at the time, but now Bethe shared some important information with me.
It seems that in September 1941 Heisenberg had come to Copenhagen, where he met Niels Bohr. Denmark was then an occupied country.(*) The ostensible reason for Heisenberg's visit was to take part in a conference of astronomers organized by the so-called German Cultural Institute, an outfit set up to distribute Nazi propaganda. Bohr boycotted the conference and there was some question as to whether he would see Heisenberg at all, even though in the late 1920's and early 1930's the two of them had hammered out together what is known as the "Copenhagen interpretation" of quantum mechanics, still in use today. It seems Bohr wanted at least to invite Heisenberg for dinner, but his wife Margrethe, who never much liked Heisenberg, objected; she felt that his whole visit was "hostile."
Bohr evidently managed to persuade her. After dinner, he and Heisenberg had a private talk, the contents of which have become one of the most controverted aspects of Heisenberg's entire wartime record. Of this discussion, Bohr's son Aage, his father's closest wartime confidant and a Nobel Prize-winning physicist in his own right, has written:
In a private conversation with my father, Heisenberg brought up the question of the military applications of atomic energy. My father was very reticent and expressed his skepticism because of the great technical difficulties that had to be overcome, but he had the impression that Heisenberg thought that the new possibilities [perhaps an implicit reference to plutonium] could decide the outcome of the war if the war dragged on.
Then what happened? According to my informant Hans Bethe, Heisenberg gave Bohr a drawing of something purporting to be the design of a German nuclear weapon. Later this drawing was "transmitted to us in Los Alamos." I did not ask Bethe how much later, and I also did not ask him what he meant by "transmitted." He told me that he and Edward Teller, asked to analyze the drawing, saw at once that it was a nuclear reactor. "But our conclusion was, when seeing it, these Germans are totally crazy. Do they want to throw a reactor down on London?"
My New Yorker profile of Bethe, which included this quotation, marked the first time anyone had ever mentioned such a sketch in print. Both Powers and Rose linger over the event, but they draw from it almost opposite conclusions.
Powers is convinced that, in passing classified information to Bohr, Heisenberg committed the act of a traitor -- a traitor, that is, to Germany. In other words, Heisenberg as Powers portrays him is to be considered not a Nazi collaborator but a hero of the Resistance. For Rose, by contrast, in showing the drawing Heisenberg meant to intimidate Bohr, to convince him that, since the atomic bomb would play a role in the forthcoming "Pax Nazica" (Rose's term), he should resolve to throw in his lot with the German scientists.
Both powers and Rose have persuaded themselves that Heisenberg really did hand Bohr a secret sketch of a German nuclear weapon of some sort. But did he? In 1994, Abraham Pais, Bohr's biographer, called me into his office at Rockefeller University. Some months earlier, Powers had asked him what he knew about the drawing. It seems that Powers had received a letter from Aage Bohr stating flatly that "Heisenberg certainly drew no sketch of a reactor during his visit in 1941. The operation of a reactor was not discussed at all." Nor, according to Aage, did Bohr know anything about plutonium until he was briefed about the Allied project after escaping from Denmark in the fall of 1943.
I was taken aback by this news from Pals. Had I propagated a serious error? I now queried everyone I knew who had had a senior role at Los Alamos. Bethe repeated in writing what he had told me earlier; no one else seemed to know anything. Then I made contact with the late Robert Serber, one of Oppenheimer's closest: collaborators and a man noted for both his excellent memory and his extensive store of documents. Serber not only filled me in on what had happened but also sent me some corroborating papers.
When Bohr got to England in September 1943, he was briefed by the British on the Allied nuclear-weapons program. Whether he told them what he knew about the German program is uncertain. But upon arriving in the United States in early December, he met with General Leslie R. Groves, who was in charge of the Manhattan Project, and apparently showed him some kind of drawing. Groves was sufficiently alarmed to alert Oppenheimer, and on December 31, just after Bohr arrived at Los Alamos with his son, Oppenheimer called together a select group of staff members to meet them.
Serber gave me a copy of the letter Oppenheimer sent to Groves after the meeting. It lists the attendees, and I managed to contact all of those still alive: Victor Weisskopf, Robert Bacher, Aage Bohr, Teller, and Bethe, in addition to Serber himself, who recalled coming in a little late and being told by Oppenheimer that they were discussing a proposal of Heisenberg's for a nuclear weapon and being shown the drawing, which he recognized as a reactor.
No one I spoke with could say whether the drawing was supposed to have been made by Heisenberg or was done by Bohr from memory, and the drawing itself seems to have vanished. In any case, Bethe and Teller wrote up a report showing that such a reactor could never explode like a nuclear weapon. No reactor could: this is what Frisch and Peierls had understood in 1940. A reactor operates with U-238, which only fissions when it is struck by slow neutrons, while a bomb is made of U-235 or plutonium, both of which are fissionable by fast neutrons; the entire explosive reaction in a bomb lasts only a hundredth of a microsecond.
Whether Heisenberg ever really apprehended this distinction is another subject of vehement debate. He himself said he did, and Powers agrees with him. Goudsmit and Rose say he did not, and I agree with them. The Farm Hall transcripts record a discussion among the Germans just after they first learned about Hiroshima, and it is clear to me that they lacked even a rudimentary understanding of how a nuclear weapon works. In a few days, Heisenberg figured it out and gave his fellow detainees a lecture; from their comments, it is obvious they were hearing about all this for the first time.
In reading Bethe and Teller's report, I realized that this was not just any reactor they were analyzing but a particular design Heisenberg had clung to even though a number of junior theorists in the Uranverein had demonstrated its inefficiencies. Specifically, the design involved layers of uranium metal submerged in "heavy water"--water consisting of oxygen and heavy hydrogen, a rare isotope with one extra neutron. The Germans used heavy water to try to moderate the neutrons in their reactor designs, but it was very hard to come by and they never had enough of it. To me, this detail signified that the drawing was indeed something that had come out of the Uranverein.
But how to reconcile all this with Aage Bohr's absolute certainty--which he conveyed to me once again in a message delivered by Pais--that no reactor was discussed when his father met Heisenberg in 1941 and that no drawing changed hands? Here I will hazard a guess: the drawing came to Bohr from someone else on some other occasion. Indeed, the notion that Heisenberg gave Bohr the drawing simply does not fit his character. Although never a Nazi, Heisenberg was a patriotic German, and both during and immediately after the war he told several people he had wanted the Germans to win. As he confided to Bethe, he was afraid that if the Allies were victorious they would level Germany and destroy German culture; but if the Germans won, the "good Germans" would take over and restore things to the way they had been before the Nazis.
What I think happened is that someone else from the Uranverein must have visited Bohr and given him the information. A likely candidate, it seems to me, is the physicist Hans Jensen, who was in Copenhagen in 1942 and did discuss the German program with Bohr. Since Bohr was then still persuaded that, in any practical sense, nuclear weapons were impossible, he probably filed Jensen's report somewhere in his head until he was briefed in England about the Allied project. Then he recalled what he had been told and, perhaps, drew a picture. I cannot prove this, but there are some things about this history that we may never know for sure.
Postscript: When I first saw the Farm Hall transcripts in 1992, I thought they had the makings of an interesting play. This is precisely what the well-known British playwright Michael Frayn has undertaken to do in Copenhagen, which is now enjoying a successful run in London.
Frayn is not a physicist, but he has evidently read a great deal, and for the rest he has let his imagination wander. Some things--facts, names--he has gotten wrong; they are minor. But what is not minor is a bit of dialogue he has given to Bohr. Referring to Werner Heisenberg, Bohr says, "A White Jew. That's what the Nazis called him. He taught so-called Jewish physics. And refused to stop. He stuck with Einstein and relativity, in spite of the most terrible attacks."
Now, it is true that Heisenberg had been attacked for doing "Jewish physics," and had even been called a "White Jew." But in July 1938, with the help of a family connection, he was vetted and cleared by Heinrich Himmler himself, who took the occasion to suggest he dissociate himself from the "personal and political attitude of the scientists involved." In other words, German physicists could keep relativity, but without Einstein.
This understanding of things was duly codified at a conference in the Tyrolean Alps in November 1942 attended by 30 German scientists, including Heisenberg. The summary report, written by yon Weizsäcker, stated that "one must reject the imposition of the physical relativity theory into a world philosophy of relativism, as has been attempted by the Jewish propaganda press of the previous era." The report also stated that "Einstein [had] merely followed up already existing ideas consistently and added the cornerstone." This does not sound like sticking with Einstein; far from it.
Still, Frayn does seem to me to have captured something of Heisenberg's moral ambiguity. His Heisenberg is neither a Resistance hero nor a simple Nazi collaborator--in Copenhagen, he does not pass the drawing on to Bohr--but something more interesting and perhaps more troubling. Frayn raises the question of why Heisenberg and, for that matter, Bohr never did the relatively simple calculation performed by Frisch and Peierls: the one that showed a bomb could be built. Certainly both of them were capable of it. The suggestion of Frayn's play is that somewhere deep in their psyches they were held back because they did not want to know the answer.
Perhaps so. In any case, this is another thing about the history I have been recounting that will probably never be known for sure.
(*) Degussa is still in business. It has a Website with a smiling face, and one of its activities has been to supply Iraq with nuclear material. [See From Cooperation to Complicity: Degussa in the Third Reich below]
(*) Denmark was not the only occupied country Heisenberg visited in the course of the war. In December 1943, he went to Krakow on the invitation of his brother's old schoolmate Hans Frank, then enthusiastically engaged, as the governor-general of Poland, in supervising the extermination of Polish Jewry; one wonders what they talked about.
Nazis and the Bomb by Mark Walker How close were the Nazis to developing an atomic bomb? The truth is that National Socialist Germany could not possibly have built a weapon like the atomic bombs dropped on Hiroshima or Nagasaki. This was not because the country lacked the scientists, resources, or will, but rather because its leaders did not really try. They were certainly trying to win the war. And they were willing to devote huge amounts of resources to building rockets, jet planes, and other forms of deadly and sometimes exotic forms of military technology. So why not the atomic bomb? Nazi Germany, it turns out, made other choices and simply ran out of time. A nuclear program is born In January of 1939, the German chemists Otto Hahn and Fritz Strassmann published the results of an historic experiment: after bombarding uranium with neutrons—neutrally charged particles—they found barium, an element roughly half the size of uranium. Their former colleague Lise Meitner, who a few months before had been forced to flee Germany and seek refuge in Sweden, and her nephew Otto Frisch realized that the uranium nucleus had split in two. These revelations touched off a frenzy of scientific work on fission around the world. The German "uranium project" began in earnest shortly after Germany's invasion of Poland in September 1939, when German Army Ordnance established a research program led by the Army physicist Kurt Diebner to investigate the military applications of fission. By the end of the year the physicist Werner Heisenberg had calculated that nuclear fission chain reactions might be possible. When slowed down and controlled in a "uranium machine" (nuclear reactor), these chain reactions could generate energy; when uncontrolled, they would be a "nuclear explosive" many times more powerful than conventional explosives. Researchers knew that they could manufacture significant amounts of uranium 235 only by means of isotope separation. At first German scientists led by the physical chemist Paul Harteck tried thermal diffusion in a separation column. In this process, a liquid compound rises as it heats, falls as it cools, and tends to separate into its lighter and heavier components as it cycles around the column. But by 1941 they gave up on this method and started building centrifuges. These devices use centripetal force to accumulate the heavier isotopes on the outside of the tube, where they can be separated out. Although the war hampered their work, by the fall of the Third Reich in 1945 they had achieved a significant enrichment in small samples of uranium. Not enough for an atomic bomb, but uranium 235 enrichment nonetheless. Nearing a Nazi bomb Uranium machines needed a moderator, a substance that would slow down the neutrons liberated by chain reactions. In the end, the project decided to use heavy water—oxygen combined with the rare heavy isotope of hydrogen—instead of water or graphite. This was not (as one of the many myths associated with the German nuclear weapons effort had it) because of a mistake the physicist Walther Bothe made when he measured the neutron absorption of graphite. Rather, it appeared that the Norsk Hydro plant in occupied Norway could provide the amounts of heavy water they needed in the first stage of development at a relatively low cost. The Norwegian resistance and Allied bombers eventually put a stop to Norwegian production of heavy water [While a Norwegian Resistance Coup succeeded in destroying the heavy-water stocks and all nine saboteurs made it to safety, the Nazis had the heavy-water apparatus up and running a mere five months later, instead of the one to two years the raid's plotters had hoped for]. But by that time it was not possible to begin the production of either pure graphite or pure heavy water in Germany. In the end, the German scientists had only enough heavy water to conduct one or two large-scale nuclear reactor experiments at a time. By the very end of the war, the Germans had progressed from horizontal and spherical layer designs to three-dimensional lattices of uranium cubes immersed in heavy water. They had also developed a nuclear reactor design that almost, but not quite, achieved a controlled and sustained nuclear fission chain reaction. During the last months of the war, a small group of scientists working in secret under Diebner and with the strong support of the physicist Walther Gerlach, who was by that time head of the uranium project, built and tested a nuclear device. At best this would have been far less destructive than the atomic bombs dropped on Japan. Rather it is an example of scientists trying to make any sort of weapon they could in order to help stave off defeat. No one knows the exact form of the device tested. But apparently the German scientists had designed it to use chemical high explosives configured in a hollow shell in order to provoke both nuclear fission and nuclear fusion reactions. It is not clear whether this test generated nuclear reactions, but it does appear as if this is what the scientists had intended to occur. Time runs out All of this begs the question, why did they not get further? Why did they not beat the Americans in the race for atomic bombs? The short answer is that whereas the Americans tried to create atomic bombs, and succeeded, the Germans did not succeed, but also did not really try. This can best be explained by focusing on the winter of 1941-1942. From the start of the war until the late fall of 1941, the German "lightning war" had marched from one victory to another, subjugating most of Europe. During this period, the Germans needed no wonder weapons. After the Soviet counterattack, Pearl Harbor, and the German declaration of war against the United States, the war had become one of attrition. For the first time, German Army Ordnance asked its scientists when it could expect nuclear weapons. The German scientists were cautious: while it was clear that they could build atomic bombs in principle, they would require a great deal of resources to do so and could not realize such weapons any time soon. Army Ordnance came to the reasonable conclusion that the uranium work was important enough to continue at the laboratory scale, but that a massive shift to the industrial scale, something required in any serious attempt to build an atomic bomb, would not be done. This contrasts with the commitment the German leadership made throughout the war to the effort to build a rocket. They sunk enormous resources into this project, indeed, on the scale of what the Americans invested in the Manhattan Project. Thus Heisenberg and his colleagues did not slow down or divert their research; they did not resist Hitler by denying him nuclear weapons. With the exception of the scientists working on Diebner's nuclear device, however, they also clearly did not push as hard as they could have to make atomic bombs. They were neither heroes nor villains, just scientists working on weapons of mass destruction for Hitler's Germany.
This is a schematic rather than a blueprint for an actual atomic bomb, and its unknown creator may have drawn it after the war. But it supports evidence discussed in this article that the Germans sought to develop a nuclear weapon.
Whereas scientists could only use natural uranium in a uranium machine, Heisenberg noted that they could use pure uranium 235, a rare isotope, as an explosive. In the summer of 1940, Carl Friedrich von Weizsäcker, a younger colleague and friend of Heisenberg's, drew upon publications by scholars working in Britain, Denmark, France, and the United States to conclude that if a uranium machine could sustain a chain reaction, then some of the more common uranium 238 would be transmuted into "element 94," now called plutonium. Like uranium 235, element 94 would be an incredibly powerful explosive. In 1941, von Weizsäcker went so far as to submit a patent application for using a uranium machine to manufacture this new radioactive element.
Nazis and the Bomb
by Mark Walker
How close were the Nazis to developing an atomic bomb? The truth is that National Socialist Germany could not possibly have built a weapon like the atomic bombs dropped on Hiroshima or Nagasaki. This was not because the country lacked the scientists, resources, or will, but rather because its leaders did not really try.
They were certainly trying to win the war. And they were willing to devote huge amounts of resources to building rockets, jet planes, and other forms of deadly and sometimes exotic forms of military technology. So why not the atomic bomb? Nazi Germany, it turns out, made other choices and simply ran out of time.
A nuclear program is born
In January of 1939, the German chemists Otto Hahn and Fritz Strassmann published the results of an historic experiment: after bombarding uranium with neutrons—neutrally charged particles—they found barium, an element roughly half the size of uranium. Their former colleague Lise Meitner, who a few months before had been forced to flee Germany and seek refuge in Sweden, and her nephew Otto Frisch realized that the uranium nucleus had split in two. These revelations touched off a frenzy of scientific work on fission around the world.
The German "uranium project" began in earnest shortly after Germany's invasion of Poland in September 1939, when German Army Ordnance established a research program led by the Army physicist Kurt Diebner to investigate the military applications of fission. By the end of the year the physicist Werner Heisenberg had calculated that nuclear fission chain reactions might be possible. When slowed down and controlled in a "uranium machine" (nuclear reactor), these chain reactions could generate energy; when uncontrolled, they would be a "nuclear explosive" many times more powerful than conventional explosives.
Researchers knew that they could manufacture significant amounts of uranium 235 only by means of isotope separation. At first German scientists led by the physical chemist Paul Harteck tried thermal diffusion in a separation column. In this process, a liquid compound rises as it heats, falls as it cools, and tends to separate into its lighter and heavier components as it cycles around the column. But by 1941 they gave up on this method and started building centrifuges. These devices use centripetal force to accumulate the heavier isotopes on the outside of the tube, where they can be separated out. Although the war hampered their work, by the fall of the Third Reich in 1945 they had achieved a significant enrichment in small samples of uranium. Not enough for an atomic bomb, but uranium 235 enrichment nonetheless.
Nearing a Nazi bomb
Uranium machines needed a moderator, a substance that would slow down the neutrons liberated by chain reactions. In the end, the project decided to use heavy water—oxygen combined with the rare heavy isotope of hydrogen—instead of water or graphite. This was not (as one of the many myths associated with the German nuclear weapons effort had it) because of a mistake the physicist Walther Bothe made when he measured the neutron absorption of graphite. Rather, it appeared that the Norsk Hydro plant in occupied Norway could provide the amounts of heavy water they needed in the first stage of development at a relatively low cost.
The Norwegian resistance and Allied bombers eventually put a stop to Norwegian production of heavy water [While a Norwegian Resistance Coup succeeded in destroying the heavy-water stocks and all nine saboteurs made it to safety, the Nazis had the heavy-water apparatus up and running a mere five months later, instead of the one to two years the raid's plotters had hoped for]. But by that time it was not possible to begin the production of either pure graphite or pure heavy water in Germany. In the end, the German scientists had only enough heavy water to conduct one or two large-scale nuclear reactor experiments at a time.
By the very end of the war, the Germans had progressed from horizontal and spherical layer designs to three-dimensional lattices of uranium cubes immersed in heavy water. They had also developed a nuclear reactor design that almost, but not quite, achieved a controlled and sustained nuclear fission chain reaction. During the last months of the war, a small group of scientists working in secret under Diebner and with the strong support of the physicist Walther Gerlach, who was by that time head of the uranium project, built and tested a nuclear device.
At best this would have been far less destructive than the atomic bombs dropped on Japan. Rather it is an example of scientists trying to make any sort of weapon they could in order to help stave off defeat. No one knows the exact form of the device tested. But apparently the German scientists had designed it to use chemical high explosives configured in a hollow shell in order to provoke both nuclear fission and nuclear fusion reactions. It is not clear whether this test generated nuclear reactions, but it does appear as if this is what the scientists had intended to occur.
Time runs out
All of this begs the question, why did they not get further? Why did they not beat the Americans in the race for atomic bombs? The short answer is that whereas the Americans tried to create atomic bombs, and succeeded, the Germans did not succeed, but also did not really try.
This can best be explained by focusing on the winter of 1941-1942. From the start of the war until the late fall of 1941, the German "lightning war" had marched from one victory to another, subjugating most of Europe. During this period, the Germans needed no wonder weapons. After the Soviet counterattack, Pearl Harbor, and the German declaration of war against the United States, the war had become one of attrition. For the first time, German Army Ordnance asked its scientists when it could expect nuclear weapons. The German scientists were cautious: while it was clear that they could build atomic bombs in principle, they would require a great deal of resources to do so and could not realize such weapons any time soon.
Army Ordnance came to the reasonable conclusion that the uranium work was important enough to continue at the laboratory scale, but that a massive shift to the industrial scale, something required in any serious attempt to build an atomic bomb, would not be done. This contrasts with the commitment the German leadership made throughout the war to the effort to build a rocket. They sunk enormous resources into this project, indeed, on the scale of what the Americans invested in the Manhattan Project.
Thus Heisenberg and his colleagues did not slow down or divert their research; they did not resist Hitler by denying him nuclear weapons. With the exception of the scientists working on Diebner's nuclear device, however, they also clearly did not push as hard as they could have to make atomic bombs. They were neither heroes nor villains, just scientists working on weapons of mass destruction for Hitler's Germany.
The Houtermans Memoranda and the Heereswaffenamt
"And there is something else interesting: Erwin K. Oppenheimer maintained that the bomb that was dropped on Japan was of German provenance".
--Edgar Mayer and Thomas Mehner, "Das Geheimnis der deutschen Atombombe" 1
One of the most problematical documents to explain from the standpoint of the postwar Allied Legend is the top secret memorandum concerning the development of an atom bomb anonymously submitted to the German Army Ordnance Bureau (Heereswaffenamt) in early 1942. This document not only correctly estimated the critical mass for a Uranium-235 based bomb, but also indicated the possibility of transmutation of uranium into plutonium - called "Element 94" by the memorandum - and its use in a bomb. The memorandum's origin and authorship has been attributed to various interred Farm hall scientists, including Dr. Kurt Diebner. But the authorship is unknown, and the problem of its existence remains: How could the German army, knowing that the required amount of uranium for a nuclear bomb was comparatively small and therefore technically feasible, not have pursued its development? And how could they have pursued such laughably pathetic attempts toward a functioning reactor? The mystery only deepens when we consider a possible ancestry for the Heereswaffenamt memo written in a paper the previous year.
In 1941, Baron Manfred von Ardenne decided to circulate an unusual paper by his colleague Dr. Fritz Houtermans. The full title of the paper was "On the Question of the Release of Nuclear chain reactions, by Fritz G. Houtermans: A Communication from the Laboratory of Manfred Von Ardenne, Berlin-Lichterfelde-Ost." 2 The paper is remarkable in several respects, not the least for its revealing table of contents:
I. General Point of View
- Isotope Separation
V. Chain Reactions at Final Trial Volumes
The general outline suggests that Houtermans had already thought his way through the process, not only of initiating nuclear explosions via fast neutrons, but also of the transformation of U235 into higher elements not chemical identifiable with it. This is the first step toward plutonium, and to the use of plutonium rather than U235 as the explosive fuel for a bomb. The contents of the paper confirms that this is what Houtermans has figured out in no uncertain terms:
We are able to envision here an apparatus, that would allow...a certain amount of U235 to undergo nuclear reaction, simultaneously as an isotope transforming apparatus. The advantage vis-a-vis an isotope enrichment apparatus is therefore that the newly-created product, which would have an atomic number of 93 or more, is not chemically identical with uranium, and therefore is separable by chemical methods. Now since much larger amounts, namely 139 times more, of U238 are available, so the amount that would be convertible as fuel for a chain reaction is, from the standpoint of our theme, much more important than isotope separation that would result in mere U235.4
In other words, before the 1942 Heereswaffenamt memo (which not only gave a critical mass of a bomb with U235 as the explosive fuel that is within the range of accuracy, but which also indicates the transformation of uranium into plutonium in a reactor as an alternative fuel returning more bang for the Reichsmark) Houtermans has clearly seen another path to the atom bomb. He may therefore also be considered a leading candidate, if not the leading candidate, for the authorship of the anonymous Heereswaffenamt memorandum. His Jewish background would explain why the memorandum was authored anonymously.
So, having speculated that Nazi Germany had actually pursued a uranium bomb as the primary component of its bomb, and conducted a large and very secret uranium enrichment project in order to acquire it, we now come to the subject of the possibility of a plutonium bomb project, conducted once again in secret, and far from the "public exposure" laboratory tinkering of the Farm Hall scientists. In this respect there has already been one indication: the allegation of a second nuclear test of a bomb with a very small critical mass via the process of boosted fission, near the Three Corners region of Thuringia, an area that has the highest gamma background radiation in all of Germany.
Are there corroborating indications that the Germans might have successfully developed an atomic reactor, and hence, plutonium, in the secret recesses of Kammler's SS black programs secret weapons empire? Henry Picker, in his book "Hitler's Table Talks", makes one significant statement. Not only does he indicate that the Reichspost had something to do with the atom bomb project, but he offers more detail. The bomb was to be constructed in a plant "in an underground SS factory in the southern Harz mountains, which had a foreseen production capacity of 30,000 workers." 5 Once again, the trail leads back to the SS, the southern Harz mountains of Thuringia, and large underground factories. This facility, according to Picker, "was transferred back to the USSR by the Red Army" after the German surrender. 6 According to Picker, it was for this reason that Stalin reacted with such detachment when President Truman informed him of the successful test of the plutonium bomb at the Trinity site in New Mexico, for Stalin had already acquired the necessary technology to make his own atom bomb. Moreover, Stalin awarded Manfred von Ardenne the "Soviet 'Nobel Prize,' the Stalin Prize." 7 Mayer and Mehner comment on the real significance of this series of admissions:
"Everything clear? The Russians thus came into possession of some means of production - which from then until now remains unknown -and paid off Manfred Von Ardenne, who was certainly the best consultant in these things, who must have clarified for them the things the Russians had found there". 8
It is an intriguing idea, for we have already discovered a possible plutonium bomb detonation near Ohrdruf very late in the war. 9 This would of necessity imply that the Germans had acquired a successful atomic reactor, the question is, where? In any case, the reason for lack of knowledge about this project is clear: it was in the control of the SS, and therefore, within the portfolio of the security-obsessed General Kammler.
In any case, Houtermans' reactor concept was significantly different than Heisenberg's, or for that matter, even Enrico Fermi's successful atomic pile at the University of Chicago, since it aimed at the production not of energy, but of radioactive isotopes. For this reason, it would be able to operate at low temperature using liquid methane as a moderator, rather than heavy water or graphite. This meant that it would be an efficient producer of "element 93 or higher" that could be chemically separated and used as a nuclear explosive.10
This is significant, for it differentiates the von Ardenne-Houtermans effort both from the Heisenberg effort to design and construct a working atomic pile, and from Enrico Fermi's success in doing so .11
So at one end of the war, ca. 1945, we find the allegations on tested weapon of small critical mass which, if true, is most liked that of a plutonium bomb using a process of boosted fission, and at the other end, ca. 1941, we have a paper outlining a project to achieve a reactor for the production of the explosive fuel of such a bomb. There is an odd piece of corroboration that the Germans may also have been perilously close to, if not in actual possession of, a plutonium atom bomb, from the Pacific Theater and the Japanese program. Robert Wilcox, in his "Japan's Secret War", recounts how the Spanish Nationalist government successfully ran a spy ring both for the Germans and for the Japanese, an espionage operation that had no little success in penetrating the Manhattan Project, even to the extent of acquiring in 1943 the earliest Allied designs for a detonator for such a bomb. Interviewing Angel Alcazar de Velasco, the alleged head of the ring, Wilcox quotes a rather astonishing statement:
"The information was that the American work on a nuclear weapon was very advanced but they had a long way to go. There were even notes about the detonator. It was similar to one already in use by the Germans". 12
A complicated detonator - presumably for use in a plutonium bomb, since the detonator mechanism for a uranium bomb is a much simpler piece of equipment - already in use by the Germans in 1943!? Why would the Germans have had the need for such a complex detonator? The timing of the allegation is also disturbing, since it corroborates the assertions of the Japanese military attaché in Stockholm, that the Germans were using some type of weapon of mass destruction on the Eastern Front ca. 1943, in the region of Kursk. 13 But Houtermans was interested in more than just atom bombs. Even Paul Lawrence Rose admits that Houtermans' role in Nazi atom bomb research "remains enigmatic." 14 The reason why, though, is clear enough, once its enormous implications are understood, for Houtermans' real specialty lay in the first theoretical description of the process of thermonuclear fusion of heavy hydrogen (deuterium and tritium) atoms through high heat in stars, the very heat produced by an uncontrolled chain reaction.15 With this, we are a step closer to unlocking the riddle of just exactly what types of weapons Kammler's "think tank" was working on, for if Hotelmans' idea was seized upon, then hydrogen bombs would have been the next logical progression in the "technology tree" from the atom bomb, just as it was for the Americans and Russians after the war. Is there any indication the this was in fact the real ultimate goal of the secret German SS atom bomb program? In other words, was it really an atom bomb program at all? Or was it a hydrogen bomb program?
Fantastic as it may be to believe, the latter possibility would seem to be the actual case. The letter of Professor Lachner referred to previously also gives further illumination on the goal of Kammler's SS Sonderkommando:
Work was also conducted on the hydrogen bomb. A factory for the manufacture of heavy hydrogen was constructed in Norway but was of course destroyed by the enemy. The small uranium bombs were primarily intended as detonators for the hydrogen bombs, so their immediate use was not contemplated.16
Another corroboration for this astonishing assertion may be found in a pre-war Austrian patent for a "molecular bomb", an early version of the hydrogen bomb, from 1938.17 In any case, Professor Lachner asserts unequivocally that the real goal of the project was weapon more terrifying and destructive than the atom bomb.
Another factor is worth mentioning in this regard. The pursuit of the hydrogen bomb would also explain why the Nazis were interested in small atom bombs, made smaller via boosted fission, for a hydrogen bomb, at least with the technology available back then, would have been an enormously heavy and cumbersome object. The quest for "miniaturization" was therefore another practical aim: any such bomb would have to be made small enough for German bombers or rockets to carry, and even then, only the very largest bombers or rockets would have been up to the task, if at all.18
But to produce hydrogen bombs, one must have an adequate supply of the heavy hydrogen isotopes deuterium and tritium. Here again, however, the Allied Legend intervenes, and maintains that after the successful Allied destruction of the Norwegian heavy water plant at Ryukon, German production of the precious destructive substance was never able to recover, and, as a consequence, heavy water for a moderator in reactors (much less a hydrogen bomb!) was never in enough supply. The further implication of this assertion is, of course, that the failure of Heisenberg and other scientists to construct a reactor based on heavy water as a moderator was doomed to failure because of the lack of supply. But again, the reality was quite different. Dr. Diebner in an exchange with Dr. Wirtz - both later interred at Farm Hall - indicated that a complete heavy water plant was built in Germany by the end of 1943.19 However, revelations made at the end of the war were even more important as a means of measuring the truly significant extent of German heavy water production: a large heavy water factory, hitherto entirely unknown, had been discovered by the Allies in Kiel in northern Germany. But most importantly, after the German reunification in 1989, when the vast SS underground factories in the Harz region of Thuringia in the former eastern zone were rediscovered, many of these were found to contain several large electrical generators, enough to supply power for a few small cities! 20
Such high electrical output would certainly not have been needed for the last Führer Headquarters, but it certainly would have been required for factories separating uranium isotope(especially if they used von Ardenne's cyclotron process), and that manufactured heavy water. Was the hydrogen bomb the real goal? Does this explain the reason that, if Germany did have the atom for such a bomb, it (or they) were seldom if ever actually used, being husbanded as detonators for something far more powerful? Does this also explain, in part, the real reason for the curtain of secrecy that fell over Kammler's special SS "think tank" command structure?
One indication that this may be so were remarks made by Dr. Josef Göbbels to the Italian officer Luigi Romersa who witnessed the Rügen atom bomb test. According to Romersa, Göbbels told him "Heavy water is an important material in the manufacture of the disintegration bomb. 21 We had already before the war made some headway in the direction..." 22 Headway indeed, if an Austrian patent for prototype had already been taken out in 1938! 23
That the ultimate goal of the German atom bomb project was the hydrogen bomb, and not the atom bomb at all, seems in retrospect both quite logical and quite disconcerting.
1 Edgar Mayer and Thomas Mehner, Das Geheimnis der deutschen Atombombe: Gewann Hitlers Wissenschaftler den nuklearen Wettlauf doch? Die Geheimprojekte bei Innsbruck, im Raum Jonastal bei Arnstadt und in Prague
2 Thomas Powers, Heisenberg's War. The table of contents page of the original memorandum may be found in Mayer and Mehner, Das Geheimnis.
4 Mayer and Mehner, Das Geheimnis.
5 Henry Picker, Hitler's Tischgespräche im Führerhauptquartier, 2 Auflage (Berlin: Propylän Taschenbuch bei Ullstein, 1997), cited in Mayer and Mehner, Das Geheimnis.
7 Mayer and Mehner, Das Geheimnis, citing Picker.
9 Uranium could of course have been used in a boosted fission device, butthe process works better with plutonium, and plutonium would more likely account for such a small critical mass as was reported, namely, 100 grams, since more than that would have been necessary for a uranium bomb even with boosted fission.
10 Rose, op. cit.
12 Wilcox cit.
13 The attaché actually maintained that these weapons - whatever they were - were also used in the "Crimea", making it most likely during the siege of the Russian fortress of Sevastopol in 1942. Thus would seem to weigh very heavily against this mystery weapon being an atom bomb. But if not, what other weapon could have caused such destruction? Powers notes that Allen Dulles in Zurich received reports of a German project in "vast underground factories" that were after "putting out a new explosive in aerial bombs. He has even heard that the container of the explosive is spherical." (Rose, op. cit.) A spherical detonator, of course, is the type of implosion-compression detonator used to assemble the critical mass of a plutonium bomb.
14 Rose, op. cit.
15 Q.v. Powers, Heisenberg's War.
16 Mayer and Mehner, Das Geheimnis.
18 It should be recalled that the first hydrogen bomb, America's "Mike", weighed several tons, and was impractical as an actual weapon. America's first operational hydrogen bomb actually weighed several tons. It is difficult to imagine any existing aircraft in the German arsenal, not even the enormous Ju 390, as being up to the task of delivering a hydrogen bomb, and the specifications for the A9/10 Amerikarakete are far below what would be needed. The only practical method of delivering a hydrogen bomb would have been via a large submarine or ship to a port city, a militarily quite risky venture, and one that, for the German crews involved, would have been a one way venture.
19 Mayer and Mehner, Das Geheimnis.
22 Mayer and Mehner, Das Geheimnis.
23 Such a patent would have been immediately classified as a "Geheime Reichsache" or "secret state matter", i.e., a matter of national security as would now be said. As such, it would have definitely made its way directly to Kammler's "think tank."
Declassified files reopen "Nazi bomb" debate
Did leading German physicists choose not to "know" how to build an A-bomb?
By Stanley Goldberg and Thomas Powers
September 1992 pp. 32-40 (vol. 48, no. 07) © 1992 Bulletin of the Atomic Scientists
On the evening of August 6, 1945, the German scientists were astounded by a short report on the news. The United States had obliterated the Japanese city of Hiroshima with an atomic bomb. For a time that night, Werner Heisenberg, the chief theoretician of the German bomb program, believed that reports of a bomb were a hoax. But as further details convinced the imprisoned Germans that the news was true, they began to speak of how their own program had gone wrong. Even now, after nearly 50 years of acrimony and muddled debate, there is still no answer to the fundamental question: Why was there no German bomb?
The post-bomb arguments of Samuel Goudsmit and Heisenberg represent the heart of this debate. Goudsmit, a Dutch-born physicist, was scientific director of the Alsos mission that seized the German scientists and research reports near the end of the war. Allied scientists and intelligence authorities considered Heisenberg "the most dangerous possible German in the field because of his brain power." 
Goudsmit had known and respected Heisenberg before the war, but later his judgment turned harsh. He said he had seen secret reports proving that Heisenberg had bungled important scientific questions and had lied about his wartime role in the project. Indeed, in books, articles, and private correspondence, Goudsmit insisted that Heisenberg had concocted phony claims of moral compunction as an explanation for the humiliating German failure to produce the bomb. 
The dispute centers on Heisenberg. The Germans thought of Heisenberg as first among equals, though he never commanded anything like the line authority that J. Robert Oppenheimer had at Los Alamos. Albert Speer, Germany's economic czar, remembered Heisenberg's technical pessimism as decisive at a June 1942 meeting in Berlin that more or less ended serious German hope of a bomb. If Heisenberg said it couldn't be done in a war-torn economy, that was the end of it.
Historians have long sought one particular batch of classified files--the 270-odd pages of reports from Farm Hall, the British home where Heisenberg and nine other German scientists were held from July 3, 1945, through the end of the year. The weekly reports, compiled by British intelligence officers, were based on transcripts of the scientists' secretly recorded conversations via microphones concealed in every room. Goudsmit hinted at the files' existence in his 1947 book, Alsos, and Gen. Leslie Groves, director of the Manhattan Project, dipped into them freely for his own 1962 memoir, Now It Can Be Told. But British authorities sealed the files for the next 30 years. Last fall the physicist Nicholas Kurti orchestrated a noisy public campaign for their release.
Declassified in February, the Farm Hall reports--the American copy still bearing Goudsmit's marginal notes in pencil--provide a vivid, intimate portrait of the German scientists who failed to build a bomb for Hitler.  Whatever triggered Goudsmit's angry charges against Heisenberg is there on paper--in the conversations reflecting deep ambivalence by Heisenberg and three friends regarding building a bomb. The reports are not the whispers of conspirators who figuratively poured sugar into gas tanks while colleagues slept; but neither do they reflect second thoughts or special pleadings from men who tried but failed to build a bomb. The Farm Hall reports expand and illuminate the history of the German bomb program, and no future attempt to explain that history can ignore them.
The two most significant reports, numbers four and five, cover the period bracketing Hiroshima, from the first terse BBC announcement at 6 p.m. on August 6, through Heisenberg's full-scale bomb physics lecture delivered to the assembled company on August 14.
The information from those reports illuminates what Heisenberg knew or quickly managed to deduce about bomb design. From a historical viewpoint, the information is important because it confronts Goudsmit's charge that Heisenberg failed to build a bomb because he simply didn't know how. But for the general reader, most striking is the attitude of the German scientists--their instinctive emotional response at hearing the news of the U.S. success. (This response helps to explain Heisenberg's pessimistic report in 1942 to Speer and other German officials on the prospects--or lack of them--for a successful German bomb. Was Heisenberg giving his honest opinion in 1942--or deliberately pricking the official balloon?)
There can be little question that the recorded responses are authentic. The Farm Hall "guests" believed that they were talking only to each other, not for the benefit of some unseen eavesdropper. On July 6, hidden microphones picked up the following conversation:
Kurt Diebner: "I wonder whether there are microphones installed here?"
Heisenberg: "Microphones installed? (laughing) Oh no, they're not as cute as all that. I don't think they know the real Gestapo methods; they're a bit old-fashioned in that respect."
On the evening of August 6, the first question in the minds of all ten scientists was, is it true? Have the Americans really built a bomb? "If the Americans have a uranium bomb then you're all second-raters," said Otto Hahn. "Poor old Heisenberg."
The question of morality arose. Carl Friedrich von Weizsäcker, Heisenberg's close friend and protégé, said in the first few minutes, "I think its dreadful of the Americans to have done it. I think it is madness on their part."
Heisenberg did not let the remark go unchallenged. "One can't say that," he responded. "One could equally well say, 'That's the quickest way of ending the war.' "
"That's what consoles me," said Hahn.
Hahn needed consoling. He had contemplated suicide in 1939 when he first realized that his December 1938 discovery of fission might lead to bombs, and he spoke of suicide again on August 6. Hahn's friends and the British officer in charge, Maj. T. H. Rittner, kept watch over him that night until he was safely asleep.
The titular chief of the German program, Walther Gerlach, responded differently, acting (in Max von Laue's words) "like a defeated general."
Later that first night, Hahn visited Gerlach in his bedroom to cheer him up. "Are you upset because we did not make the uranium bomb?" Hahn asked, and added, "I thank God on my bended knees that we did not make a uranium bomb."
Hahn had been on the periphery of the German project, busy with basic research at the Kaiser Wilhelm Gesellschaft in Berlin. His passionate disavowal of the bomb, then and later, was incidental to the German failure. Hahn's conversation with Heisenberg later that night came closer to the heart of the matter. Here is Major Rittner's paraphrase of that discussion:
Hahn explained to Heisenberg that he was himself very upset about the whole thing. He said he could not really understand why Gerlach had taken it so badly. Heisenberg said he could understand it because Gerlach was the only one of them who had really wanted a German victory, because although he realized the crimes of the Nazis and disapproved of them, he could not get away from the fact that he was working for Germany. Hahn replied that he too loved his country and that, strange as it might appear, it was for this reason that he had hoped for her defeat.
. . . They continued to discuss the same theme as before, that they had never wanted to work on a bomb and had been pleased when it was decided to concentrate everything on the engine [reactor]. Heisenberg . . . feels himself that had they been in the same moral position as the Americans and had said to themselves that nothing mattered except that Hitler should win the war, they might have succeeded, whereas in fact they did not want him to win. . . . They then went on to discuss the feelings of the British and American scientists who had perfected the bomb and Heisenberg said he felt it was a different matter in their case as they considered Hitler a criminal.
In later years, sometimes in nearly identical words, Heisenberg often repeated these remarks--save one. So far as we know, he never again said, "they might have succeeded" if they had wanted Hitler to win the war.
Two others discussed the moral issues as well--Weizsäcker and Karl Wirtz, who had been a student of Heisenberg's at Leipzig. Heisenberg, Weizsäcker, and Wirtz, in fact, had been in charge of the principal German effort to build a working reactor. "I believe the reason we didn't do it," said Weizsäcker the first evening, "was because all the physicists didn't want to do it, on principle. If we had all wanted Germany to win the war we would have succeeded." Later he and Wirtz both remarked on the irony of the situation--the Allies built the bomb with all of its terrors, while the scientists in Hitler's Germany worked only on a reactor.
Goudsmit extracted two elements from these conversations--talk of the morality of the bomb and discussions of how it was designed and built--and concluded that the Germans didn't know how to build a bomb and had concocted a phony story of moral reservations to explain their failure. Reconsidered 45 years later with the full reports at hand, his interpretation rests very uncomfortably with the facts. In the Farm Hall conversations, Heisenberg, Hahn, and the others were not expressing their doubts and reservations for the historical record; they were speaking with intimate friends in what they took to be privacy.
As to German incompetence, in 1946 Goudsmit was absolutely certain that the rigid imposition of dictated truth by incompetent administrators constrained and confined those German scientists working in the laboratory and prevented the free exercise of scientific inquiry. In a March 1946 Bulletin article, "How the Germans Lost the Race," Goudsmit claimed that German scientists believed that only thermal neutrons (neutrons that had been slowed down by repeated collisions with a non-absorbing moderator such as carbon or heavy water) could be used to fission uranium 235 and therefore, they never understood the concept of a bomb. They all believed, he argued, that a bomb was a reactor out of control. And furthermore, they did not even understand the possibility of using a reactor to produce plutonium; their vision was confined to developing a power-producing reactor.
Goudsmit believed that because of experimental errors and stupid reasoning, German scientists had rejected the possibility of using carbon as a moderator, and he concluded that because they were forced to use scarce heavy water as a moderator, it was unlikely that German scientists would have been able to produce a self-sustaining fission reaction even if the war had lasted much longer.
Contradicting Goudsmit's conclusions, a little over a year later in the August 16, 1947 issue of Nature, Heisenberg pointed out that as early as 1940, Weizsäcker had suggested a way to use a reactor to produce a new element which, Weizsäcker suggested, should be fissionable. In the Nature article, Heisenberg rejected the suggestion that the German decision not to try to build a bomb had been the result of incompetence or ignorance. Rather it had been both a political decision and a realistic response to circumstances. "The project could not have succeeded under German war conditions," said Heisenberg, but then he said much more:
From the very beginning German physicists had consciously striven to keep control of the project and had used their influence as experts to direct the work into the channels which have been mapped [in this paper]. . . . In the upshot they were spared the decision as to whether or not they should aim at producing atomic bombs. The circumstances shaping policy in the critical year 1942 guided their work automatically towards the problem of the utilization of nuclear energy in prime movers. To a German physicist, this task seemed important enough. . . .We could feel satisfied . . . with a peace-time application which [like the discovery of fission] . . . would likewise find . . . [its] beginning in Germany, and in the course of time bear fruit.
But even as Heisenberg wrote, Goudsmit's book, Alsos, was in the final stages of production. Not only did Goudsmit repeat his claims that Heisenberg and his colleagues had been incompetent bunglers, he expressed deep disappointment that his old colleague would have allowed himself to be used by the Nazis, and he was made indignant by Heisenberg's appeal to moral reticence, which he judged to be dishonest. And so the battle was joined. Philip Morrison's remarks typify the attitudes of American scientists. In a December 1947 Bulletin review of Goudsmit's book, Morrison wrote:
He [Heisenberg] has lately tried to claim that the motivation for the German work was a peaceful one, since they wanted not bombs but merely a pile. . . .
The careful story put together by Goudsmit demonstrates this account to be . . . a rationalization invented while some of the participating physicists were interned in England. The documents cited in Alsos prove amply that, no different from their Allied counterparts, the German scientists worked for the military as best their circumstances allowed. But the difference, which it will never be possible to forgive, is that they worked for the cause of Himmler and Auschwitz, for the burners of books and the takers of hostages.
Now that the summaries and partial transcripts of the Farm Hall tapes have been made public, it is difficult to understand why Goudsmit, Groves, Morrison and other Allied scientists believed Heisenberg and the others all tried or wanted to build a bomb. The Farm Hall words point to another conclusion and the complete absence of any serious German program confirms what Heisenberg and some of the others expressed.
The documentary record shows that in the autumn of 1941, the German and Allied fission programs were at essentially similar crossroads--would pursuing fission technology development result in important weapons for this war? Among scientists on both sides, there was no consensus.
In the United States, the political decision to proceed was based, in part, on the belief that the Germans had been making progress in the development of a fission bomb. But a letter written in April 1941 (recently discovered in the National Archives) from Princeton physicist Rudolph Ladenburg, a German emigré, to Lyman Briggs, Director of the National Bureau of Standards and head of the American uranium fission program, contradicts this belief. In it, Ladenburg informs Briggs that colleagues close to Heisenberg had gotten word to Ladenburg that Heisenberg's group was working on a uranium bomb, but that Heisenberg had delayed as much as possible, fearing the consequences of succeeding. In the end, the letter said, he would have to follow orders. If such a bomb was possible, it would be developed soon. 
Eight months later, by the end of the year, the Germans had decided not to go ahead. This verdict was rendered as the tide began to turn against Germany on the Eastern Front. Among the scientists, Kurt Diebner's group was convinced that a bomb made of uranium 235 or plutonium might be built with destructive potential a million times greater than the equivalent amount of dynamite. Diebner estimated that between 10 and 100 kilograms of fissile material would be required. Heisenberg, head adviser for the project, was much more circumspect. He waffled on just how much active material would be needed. He was vague when he noted that neutrons of any speed would fission uranium 235. And in early 1942, when asked outright by military authorities if results could be obtained within the next nine months, his answer was an unequivocal "no."
In June 1942, Albert Speer, who had recently been appointed Minister of Armaments and Munitions and who had the power to give a bomb development program significant impetus, met with a number of military and scientific leaders, including Heisenberg, to explore the question. Speer did so at the urging of some of those who remained convinced that nuclear technologies could be exploited in the service of war. At that meeting, Heisenberg chose to focus on the development of reactors and cyclotrons and pronounced atomic bombs to be a development for the future, not for the war. 
What ultimately emerges from the Farm Hall transcripts is that after the August 6 atomic bomb announcement, Heisenberg seems to have had two different versions of what would be required to build a bomb. This is reflected in different portions of the Farm Hall reports. First from Gerlach, who said, "If they want to get that [sufficient quantities of plutonium] they just use a whole ton." But later in the same conversation, the following exchange took place between Heisenberg and Hahn:
Heisenberg: "I still don't believe a word about the bomb but I may be wrong. I consider it perfectly possible that they have about 10 tons of enriched uranium, but not that they can have 10 tons of pure uranium 235."
Hahn: "I thought that one needed only very little 235."
Heisenberg: "If they only enrich it slightly, they can build an engine which will go but with that they can't make an explosive which will--"
Hahn: "But if they have, let us say 30 kilograms of pure 235, couldn't they make a bomb with it?"
Heisenberg: "But it still wouldn't go off, as the mean free path is still too big."
Hahn: "But tell me why you used to tell me that one needed 50 kilograms of 235 in order to do anything. Now you say one needs two tons."
At the June 1942 meeting with Albert Speer and the military experts in Berlin, Heisenberg described the amount of fissionable material required to level a city as "about the size of a pineapple."
Later on the night of August 6, when Hahn and Heisenberg were alone, Hahn again asked, "Do you think they would need as much as 30 kilograms?" Heisenberg replied, "I think so certainly, but quite honestly I have never worked it out as I never believed one could get pure 235."
I always knew it could be done with 235 with fast neutrons. That's why 235 only can be used as an explosive. One can never make an explosive with slow neutrons, not even with the heavy water machine, as then the neutrons only go with thermal speed, with the result that the reaction is so slow that the thing explodes sooner before the reaction is complete.
In response to Hahn's next question, "How does the bomb explode?" Heisenberg, without hesitation, replied as follows:
In the case of the bomb it can only be done with the very fast neutrons. . . . in order to make 1024 neutrons I need 80 reactions one after the other. . . . The mean free path is about six centimeters. In order to make 80 collisions, I must have a lump of a radius of about 54 centimeters and that would be about a ton. . . . It is conceivable they could do it with less in the following manner. They would take on a quarter of the quantity but cover it with a reflector [at Los Alamos this was referred to as a "tamper"] which would turn back the fast neutrons.
Hahn asked, "How can they take it in an aircraft and make sure that it explodes at the right moment?" Again Heisenberg was not hesitant:
One way would be to make the bomb in two halves, each one of which would be too small to produce the explosion because of the mean free path. The two halves would be joined together at the moment of dropping when the reaction would start.
Heisenberg was able to reconstruct the process within a few hours after hearing that Hiroshima had been destroyed by an atomic bomb. A week later, he had honed and refined these ideas, which he presented in a formal lecture to his colleagues. The general discussion that followed the lecture makes clear that only some of the scientists really understood bomb physics. Besides Heisenberg, this group included Harteck, Weizsäcker, and Wirtz. The others were evidently hearing much that was new to them.
When Hans Bethe, who was chief of the theoretical division at Los Alamos during the Manhattan Project, read the Farm Hall transcripts 47 years later, he was immediately struck by Heisenberg's sophistication. "My first reaction," he said, "is that Heisenberg knew a lot more than I have always thought--the fact that he reached many of these conclusions in one evening is most remarkable. In his lecture it was clear he was talking to people who were quite ignorant. Heisenberg put everything on quite a low level, even going back to fundamentals. Apparently the other people didn't know very much about fission--even including Max von Laue, who was a great physicist. But especially Walter Gerlach [the head of the German uranium project]--he knew very, very little--everything had to be explained to him as for the first time." 
The Farm Hall transcripts reveal Heisenberg's sophisticated understanding of bomb physics and that he had kept much of this understanding to himself during the war. The transcripts also provide evidence that the relationships between scientists and the military in Germany was very different from those relationships in the United States or England--and contrary to Morrison's assumptions. As Heisenberg remarked to his colleagues on the evening of August 6, 1945:
"The point is that the whole structure of the relationship between the scientist and the state in Germany was such that although we were not 100 percent anxious to do it [produce nuclear weapons], on the other hand we were so little trusted by the state that even if we had wanted to do it, it would not have been easy to get it through." Many of the German scientists at Farm Hall understood which World War II governments had been wearing the white hats and which had been wearing the black.
As Heisenberg noted in his 1947 Nature article, in 1942 the state of research and knowledge concerning nuclear fission in Germany and in the United States was comparable. But knowledge is not sufficient to build a bomb. A very large, expensive, and far-flung industrial complex must be mounted and managed. The United States decided to make that transition, a decision motivated in part by concern for Germany's progress toward a bomb. Of necessity, U.S. scientists gave up control of the products of their labors and control of how such products would be employed.
In Germany, the authorities decided against the huge effort that an industrial enterprise would require. First, it was inconceivable to the Germans that anyone else would contemplate developing a fission bomb. Second, there is evidence that Werner Heisenberg and possibly other scientists purposely reported bleak prospects to German leadership concerning near-term nuclear technology for war. These scientists also kept information from (and even lied to) colleagues who they knew would have been eager to cooperate with the Nazi leadership. Heisenberg's words from the Farm Hall tapes, "From the very beginning, German physicists had consciously striven to keep control of the project," ring true.
None of this, of course, gives general absolution to Heisenberg and his colleagues nor is it a general defense of their actions or statements before, during, or after the war. The fact remains that Heisenberg and most of his colleagues at Farm Hall never claimed a superior ethical and moral stance during the war. Perhaps the specter of such claims drove Goudsmit, Morrison, and Groves to lash out with such vehemence, with such absolute moral certainty.
As Heisenberg had often said, the situations in America and Germany were not comparable. Suppose, for instance, that the United States had worn the black hat. And suppose that American scientists, for one reason or another, had decided they could not emigrate from a fascist regime. We think there is little doubt that many of them would have chosen to walk the same kind of knife-edge that Heisenberg chose--and in such a way as to minimize the damage to themselves and to others.
1. Robert Furman, memo to file (March 7, 1944), Record Group 77, Army Corps of Engineers, entry 21, box 171, National Archives and Records Administration, Washington, D.C.
2. Samuel Goudsmit, "How the Germans Lost the Race," Bulletin of the Atomic Scientists (March 15, 1946); Samuel Goudsmit, Alsos (New York: Henry Schuman, 1947); cf., correspondence with Victor Weisskopf, Hans Bethe, Rudolf Peierls, et al., Goudsmit Papers, Niels Bohr Library, American Institute of Physics, New York, N.Y.
3. Farm Hall Transcripts, National Archives, Record Group 77, entry 22,box 163re indebted to Ed Reese and Will Mahoney in the Archives Military Reference division for their generous cooperation and assistance.)
4. For the effects of this letter on the American program see Stanley Goldberg, "Inventing a Climate of Opinion," Isis (forthcoming); for the provenance of the letter, see Thomas Powers, Heisenberg's War (New York: Alfred A. Knopf [forthcoming]), chapter 10.
5. See David Irving, Virus House (London; William Kimber, 1967); Mark Walker, German National Socialism and the Quest for Nuclear Power, 1939-1949 (Cambridge; Cambridge University Press, 1988) chapters 2-3; Powers, Heisenberg's War, chapters 13-14.
6. Hans Bethe. Interview by Thomas Powers, March 19, 1992.
From Cooperation to Complicity: Degussa in the Third Reich
Reviewed by: Avraham Barkai, Leo Baeck Institute, Jerusalem.
In his concluding lines Peter Hayes calls his book an outgrowth of "German society's collective confrontation (after a long delay), with what it did from 1933 to 1945". German business joined in this confrontation rather late, and considerations of global economic interest were certainly part of its motivation. But once it got under way it evolved in many cases as a serious attempt to learn the full truth. Archives were opened without restrictions and the commissioned scholars were provided with generous financial as well technical assistance. The result has been a still-growing number of publications sponsored by German firms that explore their role and performance in this fateful period while showing no signs of interference or censure of the author's interpretation or conclusions. 
The book under review joins this body of research as a meticulous and profound work and a masterful narration of the deeds, and mainly the misdeeds, of a German corporation deeply entangled in the murderous crimes of the Third Reich. Aware of the "risk to a scholar's reputation entailed in a task of this sort," its author implores his readers from the start to approach his "account with an open-minded and skeptical spirit.... Even as readers properly allow for ... possible seductions of proximity," they should keep in mind that the book was neither censored nor endorsed by the firm who "paid the piper" (p. xvi). Reading this volume in the suggested manner, I learned about Degussa's close connections with Henkel GmbH, the producer of the famous cleansing agent Persil, and found that this volume is all but a Persilschein for Degussa. 
This acronym of the Aktiengesellschaft Deutsche Gold- und Silberscheideanstalt vormals Roessler was introduced internally only in 1943, seventy years after the firm's incorporation, and only in 1980 was it adopted as the official name of the "far-flung multinational that bore this name in the second half of the twentieth century" (p.2). It had started in Frankfurt am Main as a small smelting operation for precious metals, but flourished through the growing demand of standardized coinages, first for the South German states after 1834 and then for the German Empire after 1871. From these beginnings it developed as a "rather little big business," in the shadows of such German corporate giants as I. G. Farben, Vereinigte Stahlwerke, Krupp or Siemens. Its chain of managers seem to have been consistent in their foresight and ability to profit from the business opportunities offered by political and military upheavals in the course of two world wars and the years between, as behooves businessmen who care for their firms and shareholders. However, by the very nature of its production lines (metal refining and its chemical byproducts), as well through a probably greater than usual neglect of moral scruples, Degussa has "left its fingerprints on many of the most dramatic--and, in some cases, criminal--aspects of German history between 1933 and 1945. Much of the gold and silver extorted from Europe's Jews or ripped from their corpses passed through Degussa's refineries, as did some of the far larger quantities of precious metals plundered from the treasuries and citizenries of occupied Europe.... The Zyklon B used to asphyxiate some one million people at Auschwitz and Majdanek was a Degussa product".
Degussa harvested most during the war, but its managers' rapid "accommodation to the ideology of the self-proclaimed Third Reich" bore elaborate fruits as early as the first years of National Socialist rule. Serving "the three state-imposed goals," Aryanization, autarky, and armament, paid off: by September 1936, Degussa could record a "fivefold increase since 1933 from shareholdings in other firms ... a stunning growth, largely through Aryanization". Such early gains were exceeded in the years to come. By the firm's own calculations of September 1946, its capital assets, after close to 120 million Reichsmark of "losses during and because of the war, and ... even after huge deductions for depreciation and damage ... were still worth nearly three times as much as ... twenty years earlier, and the total property on its balance sheets nearly four times as much. Certainly the bulk of these gains ... are attributable to the Nazi years". We may assume that in the continued possession of the spoils of the lost war Degussa was not more favored than many other German firms that flourished in the Wirtschaftswunder. The story of how they were gained, told in this book in scrupulous--at times fatiguing--statistical detail, would not have been less atrocious, however, had the firm made smaller profits or none at all, or even lost money in its transactions.
The early NSDAP connections of some of its board members may have induced Degussa to adjust to the new regime earlier and more submissively than some other German firms. If it "entailed seeming to meet the 'New Germany' halfway and amounted to taking the course of least resistance in the face of Nazi zealotry and thuggery," Degussa did so in accordance with the "conventional corporate wisdom of the time". The enrollment of longtime party members in the board was certainly part of this corporate consensus. The consideration of an ideological dimension in a work on business history, where utilitarian motivation is usually assigned as the primary and often only factor, is one of the merits of this study. Hayes traces the earlier convictions of some of the leading personnel of the firm, devoting four full pages to those of Hermann Schlosser, its chairman between 1939 and 1945 (and again 1949-59). He concludes that the man's ideological background "disposed him to do what the regime requested, from the beginning to the bitter end, even when he did not agree with all that this required" (p. 32). Even while admitting personal differences, we may assume that the higher echelons in the management of other firms shared similar nationalist outlooks. These paved the way to their almost general submission to and active cooperation in the institutional framework of the German economy, which was transformed almost immediately after 1933. Businessmen and their strong organizations, which had formerly stood unbending against any state intervention, accepted, in an astonishingly fast volte-face, the dirigist orders of the "national-socialist economic system" and the Nazi party's encroachments on the management of their firms. 
The first chapter investigates Degussa's exemplary adjustment and demonstrates the "advantageous results for the enterprise, but terrible consequences for countless Germans, as well as for those 'inferiors' the Nazi regime brutalized". Substantial profits emerged during "Aryanization," the acquisition of formerly Jewish property. Between 1933 and 1944 Degussa and its subsidiaries expended close to nineteen million RM in this competitive "enrichment-run," as described by Peter Hayes in this and previously published studies.  The author is confident that "although it is extremely difficult to specify how much these purchases improved Degussa's balance sheets and profitability, both during the Nazi period and later, there can be no doubt that Aryanization contributed appreciably to the corporation's short- and long-term success. All but two of the enterprises taken over returned substantial profits during the 1930s and 1940s; most of them remained in Degussa's possession through the 1950s, and three of them ... still did at the end of the twentieth century". Thanks to his pedantic perusal of the corporation archives we are offered very detailed accounts of these transactions. As he rightly notes, similar compilations are still scarcely available for, and therefore not comparable with the "involvement of other large German firms in Aryanization".
The confines of a review do not permit me to detail the process and its gains, but the book's tabular representation of the firm's outlays before and during the National Socialist period and its compensation payments in the aftermath needs some clarification. Personally I have repeatedly questioned the possibility that the losses of the victims of Aryanization can be estimated; similarly, I question whether the real gains of "Aryanizers" can be depicted solely in monetary terms. Hayes's table strengthens these doubts. What was the "nominal value" of a Jewish firm, in many cases quoted as essentially lower than the price paid by Degussa, and how to explain this "largesse"? According to extant research, payments to the Jewish owners were based, by order of government and party authorities, on an "Einheitswert," which was usually lower than the real "Verkehrswert." A substantial, successively growing part of the Einheitswert was subtracted by order of the party's district economic advisor (Gauwirtschaftsberater), the last instance to confirm the prices to be paid.  Additionally, how can we estimate the real value of a going concern, which under different conditions would have taken part in the expanding economy before, the "advantages" taken during, and the Wirtschaftswunder after the war? Third, how can we calculate the real values of postwar "compensation," taking--or not taking--into account the change from Reichsmark to Deutsche Mark and other economic and monetary developments? And finally how can we incorporate into such calculations the capital-interest gains of the purchaser and its loss by even "voluntary" Jewish sellers, which accrued in the many years between "Aryanization" and so-called compensation? All of these problems bolster my conviction that all such attempts of evaluation are problematic, as long as they are not based on some generally agreed upon econometric method that has not yet been and may never be developed.
The author regards those data as "an indication not only of how slowly the corporation recognized the nature of what it had done, but also of the extent (and the imperfection) of the justice nonetheless achieved" . But his summary of Degussa's gains from "Aryanization" as well as his outspoken opinion about the firm's conduct toward Jewish owners after 1945 is far more convincing than the somewhat confusing data of his tabulation. Closely tracing every case "in which the firm or a wholly or jointly owned subsidiary was a party" he demonstrates how "Degussa's representatives used every legal possibility during the restitution wrangle that followed the war to keep ... what the enterprise had obtained" (p. 106). He concludes that "there can be little doubt that the balance sheet of Aryanization remained positive for Degussa long into the postwar era". The only possible "excuse" for its conduct after 1945 into the late 1950s may be that Degussa did not behave much differently from most German firms, which tried and succeeded in keeping what they obtained during the National Socialist regime--in "Greater Germany" before the war and in occupied Europe as the spoils of war. Though only a few of these corporations have so far been investigated, and even fewer have been probed in a manner as deeply detailed as that provided in this study, what has already come to the fore suffices to confirm the dictum that the German entrepreneurs "knew no rethinking and hardly any reflection at the time of upheaval" after the war. 
What each of the involved firms could gain, and the part of those gains it could keep, depended mainly on the nature of its products and their importance for the regime's economic and political goals. In its first years these included autarky, mainly through the replacement of imports, and, starting around 1935-36, armament. The following chapters convincingly show that in both fields Degussa was almost predestined to be in the first ranks of the profiteers. The firm's experience in the production of chemicals for producing surrogates of natural rubber and fuel proved of essential importance, and the same applies to its metallurgical expertise. During the war this expertise was unscrupulously exploited in the most morbid and murderous crimes of the Holocaust. Degussa's refineries became the main processors of "Jew metals" starting from the silver spoons confiscated in the "Pawnshop Action of 1938/9" to the gold teeth of the victims murdered in the gas chambers. No fewer than seventy-six deliveries of the notorious "Melmer-Gold" (named for Bruno Melmer, the SS official responsible for these transports) reached Degussa's plants. The estimated "total quantity of fine gold that Degussa's refineries derived from these later victims may have gone as high as 5 metric tons (15 percent of Degussa's gold production from 1939 to 1945)". Degussa's staff, down to the production line, was aware of the source of these deliveries. But even if specific knowledge cannot be proven, "one simply has no reason to believe that the firm's leaders would have rejected these intakes ... even if openly confronted [with the circumstances of their origin]" The author can not imagine that "in a context of war and dictatorship, a sense of morality and feelings of shame and disgust would have arisen, let alone prevailed" against the advantages of present profits or future recognition.
He arrives at similar conclusions also in the matter of Zyklon B, the hydrogen cyanide gas used in Auschwitz and other extermination camps. That the product antedated the First World War as an effective insecticide, and that a bare one percent of the total wartime output was used to murder people is totally irrelevant to the "enduring infamy of the substance". In Hayes's book, readers can absorb the detailed account of the inventors, producers, and distributors of what became an instrument of mass murder, and begin to deal with the questions of knowledge and guilt. Zyklon B was produced by the Deutsche Gesellschaft Schädlingsbekämpfung, better known by its acronym "Degesch," a fully-owned subsidiary of Degussa. At the relevant time and place it was supplied to the SS, mainly by the Tesch & Stabenow GmbH in Hamburg. Postwar evidence from this firm's Berlin office leaves little doubt that Bruno Tesch not only knew that "our Zyklon B would be used for killing people," but even advised the SS that it could be used for that purpose "exactly as on insects, and agreed to show the SS personal how" Himmler's emphatic appreciation of Tesch, who "always has shown himself ready in absolutely exemplary fashion to comply with the orders of the Reichsführer" was certainly well deserved. In May 1946, Tesch and his chief aide were sentenced to death by a British military court, while other suppliers of Zyklon B fared better, and thanks to "a change in German law" came away with relatively short jail terms.
As for Degussa, Hayes concludes that "although Hitler's war had cost Degussa heavily ... the corporation emerged from the Third Reich richer and stronger than it had been in 1933". It reinstated many of its old managers and granted generous pensions to others, while "fending off demands from its work-force and restitution claimants with reference to the need of the utmost thrift", not to speak of the grudgingly allotted pittance of 10,000 RM as a "donation for the concentration camp inmates" in June 1945. In all these matters Degussa's managers of the postwar years acted very much like those of most other German firms, which moved from cooperation to complicity in the Nazi's crimes. Having followed his narrative, and in the light of the current state of research about the general involvement of German society in these crimes and the masses of direct or indirect beneficiaries from them,  I find it hard to differentiate between those who deserve merely "contempt" or rather "condemnation," as Peter Hayes proposes at the end of his introduction. The readiness of Degussa's present managers to face, albeit so belatedly, the past of their firm, to open their archives without restrictions and to promote this profound and merciless account certainly deserves commendation.
. To name only a few: Gerald Feldman, Allianz and the German Insurance Business, 1933-1945 ( New York: Cambridge University Press, 2001); Ludolf Herbst and Thomas Weihe, eds., Die Commerzbank und die Juden 1933-1945 (Munich: C.H. Beck, 2004); Harold James, Die Deutsche Bank im Dritten Reich (Munich: C.H. Beck, 2003): Hans Mommsen and Manfred Grieger, Das Volkswagenwerk und seine Arbeiter im Dritten Reich (Düsseldorf: ECON, 1996); and Stephan Lindner, Hoechst--Ein I.G. Farben Werk im Dritten Reich (Munich: C.H. Beck, 2005).
. The author was denied access to the archives of Henkel, "obviously of particular importance"
. See in this context Avraham Barkai, Nazi Economics, Ideology, Theory, and Policy (New Haven and London: Yale University Press, 1990
. See Helmut Genschel, Die Verdrängung der Juden aus der Wirtschaft im Dritten Reich (Göttingen: Musterschmidt-Verlag, 1966), p. 155f.; Frank Bajohr, Arisierung in Hamburg (Hamburg: Christians, 1997); Avraham Barkai, From Boycott to Annihilation (Hanover and London: University Press of New England, 1989).
. "Daß es kein Umdenken und kaum ein Nachdenken in der Umbruchsphase gab," Paul Erker in Erker and Toni Pierenkemper, eds., Deutsche Unternehmer zwischen Kriegswirtschaft und Wiederaufbau (Munich: Oldenbourg, 1999), p.16. See also Avraham Barkai, Oscar Wassermann und die Deutsche Bank (Munich: C.H. Beck, 2005).
. See Frank Bajohr, "The Beneficiaries of 'Aryanization,'" Yad Vashem Studies 26 (1968); now also Götz Aly, Hitlers Volksstaat, Raub, Rassenkrieg und nationaler Sozialismus (Frankfurt am Main: Fischer, 2005).
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