The elusive truth of Farm Hall Free

It reads like an espionage novel by John le Carré: As the Allies swept across Germany at the end of World War II, 10 German nuclear physicists suspected of being involved in a Nazi atomic weapons program—including Werner Heisenberg, Max von Laue, Otto Hahn, and Carl Friedrich von Weizsäcker—were rounded up, interrogated, and brought in July 1945 to a mansion in the English countryside, Farm Hall (see figure 1).

The “guests,” as they were officially termed by Allied intelligence, were held in that gilded cage for six months, and their conversations were secretly recorded. After the US dropped a nuclear weapon on Hiroshima on 6 August 1945, talk among the guests quickly turned to the question of complicity. Had they wanted to build an atomic weapon for Adolf Hitler?

In 1992 the transcripts of the secret recordings at Farm Hall were declassified. With some of the most famous scientists of the 20th century openly debating their involvement with the most infamous criminal regime in modern history, many anticipated a historical “smoking gun”—something that would settle the question once and for all. But the debate about the nature of the German atomic project continues to this day. How can that be?

One reason is that only the transcripts of conversations from Farm Hall survive, not the original recordings. (Those recordings were never kept: Tape-recording technology was in its infancy in 1945, and the conversations were recorded on shellac disks that were resurfaced and reused after their contents were transcribed.) And a transcript is not equivalent to a recording. The written word flattens inflections in tone, which can convey emotions like passion or anger. Moreover, the Farm Hall transcripts are not complete. The Allies recorded and transcribed only the sections they deemed important, which largely dealt with what the Germans knew about the technical aspects of bomb building. Other discussions were only summarized for Allied intelligence agents. Finally, aside from a few passages where it was deemed important to also keep the original German text, only English-language translations of the transcripts survive.

Even with those caveats, the transcripts are about as close as historians can expect to get to being in the room with their subjects. Among historians, the Farm Hall transcripts were generally seen as confirming an analysis presented by Mark Walker in his still-definitive 1989 book on the German atomic project: that there was no equivalent to the Manhattan Project in Germany because Nazi officials and German scientists believed that nuclear weapons could not be developed in time to be deployed in a war they expected to win quickly. At the same time, Walker noted, German scientists did not conspire to prevent Hitler from developing the atomic bomb. Yet he was more prescient than he knew when he wrote, in 1992, that “almost everyone interested in the mysterious Farm Hall transcripts has sought to find in them evidence for their side of the debate.”¹

The war’s aftermath

The Farm Hall transcripts first came to light in 1947, when Samuel Goudsmit (see figure 2) published Alsos, a tell-all memoir of the titular counterintelligence mission to round up German nuclear scientists at the end of the war. Goudsmit, an atomic physicist, was the scientific leader of that mission and the one who initially interrogated the Farm Hall guests in Germany. Infuriated by postwar statements by German scientists implying that they’d never had any intention of building a nuclear weapon, Goudsmit decided he needed to set the record straight.

In the book, Goudsmit disclosed that the Allies had interned the Germans at a country mansion. He recalled that when the Germans found out about the US dropping an atomic bomb on Hiroshima, their “initial reaction was one of utter incredulity.”² He asserted that Heisenberg and the others failed at developing nuclear weapons because they hadn’t understood the physics involved. To rationalize that failure, Goudsmit claimed, the guests developed what would later become known as the Lesart, or interpretation, of their wartime efforts: that German scientists sought only to build a peaceful nuclear reactor and not an atomic weapon.³

Goudsmit remained cagey about the sources he used to depict the discussions at Farm Hall in Alsos. But all pretense was left aside when the head of the Manhattan Project, Leslie Groves, included direct excerpts from the Farm Hall transcripts in his 1962 memoirs. Groves used the transcripts to justify a hobbyhorse of his own: the US decision to drop the atomic bomb on Japan. He approvingly quoted Heisenberg’s declaration at Farm Hall that the bomb was the “quickest way of ending the war.”⁴ If even his former enemy believed the US had acted morally, how could anyone question that decision?

Farm Hall in the guests’ eyes

The initial debate over the German nuclear program died down around 1949, with the onset of the Cold War. Seven years later, though, it reemerged with a vengeance when the journalist Robert Jungk published Brighter than a Thousand Suns. Jungk, a German Jew who had fled Nazism, managed to interview many prominent US, UK, French, and German nuclear scientists. Originally published in German in 1956, his work was one of the first books about the history of the atomic age. It became an immediate sensation and was translated into English in 1958.

As he later acknowledged, Jungk was taken in by the story of active resistance to Nazism that Heisenberg and Weizsäcker spun in their interviews. He depicted the Germans as actively conspiring to keep the bomb from Hitler. Jungk explicitly endorsed the most extreme version of the Lesart: that German scientists were morally superior to their US colleagues because the Germans had chosen not to work on a bomb.

Jungk was not able to access the Farm Hall transcripts. But he heard about the internment from his interviews with Heisenberg, Weizsäcker, and others. Jungk’s depiction of Farm Hall fit his argument. He alleged, for example, that Heisenberg and another interned physicist, Walther Gerlach, stated that Allied nuclear physicists would “probably” bear a “heavy burden of guilt” for the Hiroshima bombing.⁵ Remarkably, Jungk admitted late in his life that he had used the transcripts to fit what he wanted to hear. He termed Brighter than a Thousand Suns an “example of the temptation of wishful thinking in history.”⁶

The Lesart was echoed in another, lesser-known work that appeared around the same time, an essay on the history of the German nuclear project authored by two former Farm Hall guests, Erich Bagge and Kurt Diebner (see figure 3). Although they did not have access to the transcripts, the two reproduced in their essay a doctored version of Bagge’s diary from Farm Hall. The entries from 7 and 10 August 1945, which describe how the physicists reacted to the news of the Hiroshima bombing, were carefully edited to give the impression that the Germans knew that atomic weapons were possible but never thought seriously about building one. In contrast, the original diary lamented that some of Germany’s “best physicists” didn’t “lift a finger” to support work to isolate uranium-235, the isotope necessary to build atomic bombs.⁷

The transcripts are made public

In 1992 the transcripts were finally released, causing a media frenzy. Historians and journalists rushed to analyze the documents in the belief that they would finally end the debate about German atomic motives. But only a year later, with the publication of Thomas Powers’s 1993 book Heisenberg’s War: The Secret History of the German Bomb, it became clear that the transcripts would not put the issue to rest.⁸ In the book, Powers portrayed Heisenberg as a bona fide resister to Nazism who single-handedly denied Hitler the bomb.

At the other extreme of Heisenberg assessments was one offered by historian Paul Lawrence Rose, who used the Farm Hall transcripts in his 1998 book Heisenberg and the Nazi Atomic Bomb Project: A Study in German Culture to argue that Heisenberg was morally equivalent to the worst of the Nazis. Heisenberg’s statements at Farm Hall confirmed what Rose had been saying since the 1980s: that Heisenberg’s “behavior and mentality . . . bore the imprint of years of German nationalist and cultural conditioning.”⁹

But it was not just Powers and Rose who argued that the full transcripts confirmed their take on the German nuclear project. Two of the surviving Farm Hall guests also argued that the transcripts verified what they had been saying since 1945. In a 1994 review of a German-language translation of the published transcripts, Bagge claimed that building a bomb was “never discussed” by German physicists during the war.¹⁰ Weizsäcker, who had become one of the most famous public intellectuals in newly reunified Germany, went much further: He claimed that the transcripts “in fact confirmed . . . everything we said publicly.”¹¹

The debate goes mainstream

The debate about the motivations of Heisenberg and the other German nuclear scientists reached a fever pitch in 1998, with the premiere of Michael Frayn’s play Copenhagen. Although the play does not depict the Farm Hall internment, it deals with another historical episode often viewed as key to understanding the motivations of German physicists during the war: Heisenberg’s visit with Niels Bohr in occupied Copenhagen in September 1941. Much ink has been spilled speculating about what happened during that visit, but what is clear is that the military potential of nuclear power came up during a private conversation. Like the Farm Hall transcripts, Heisenberg’s visit with Bohr has been used to support drastically different interpretations of German motives. Those who see Heisenberg as a tragic hero assert that he was attempting to float a pact in which physicists on all sides would agree not to build nuclear weapons. Those who see Heisenberg as a villain claim that during the meeting he was spying for the Nazis and attempting to get Bohr to reveal what he knew about Allied nuclear plans.

Frayn’s play depicts Heisenberg, Bohr, and Bohr’s wife, Margarethe, in a dream state, in which they draft various versions of what happened during Heisenberg’s visit. Inspired by Powers’s book, the play was a smash hit in both the UK and the US and brought the German nuclear program to the attention of the broader public. And as with the transcripts, the same figures emerged to recapitulate their usual talking points. Powers termed the play “remarkable”; Rose, on the other hand, asserted that the play was an attempt to rehabilitate Heisenberg.¹² Their disagreement culminated with a face-to-face debate at a March 2002 symposium in Washington, DC, at which neither budged substantially from his position.

Bohr’s unsent letter

The media fervor surrounding Copenhagen was so great that in 2002 the Bohr family decided to release several previously unknown documents pertaining to the 1941 meeting. As it happened, Bohr had drafted numerous versions of a letter to Heisenberg—ultimately unsent—after reading the 1957 Danish translation of Jungk’s Brighter than a Thousand Suns. That edition of the book reproduced extracts from a letter Heisenberg had written to Jungk giving his account of the Copenhagen visit. What exactly Bohr was trying to say in those drafts remains hotly debated, but what is clear is that he disagreed vehemently with the version of events Heisenberg put forth in that letter.

As with the release of the Farm Hall transcripts and the premiere of Copenhagen, the revelation that Bohr had disputed Heisenberg’s account attracted the attention of the popular media. Yet even that new tranche of documents did not change any minds. Rose saw them as an “exposure” of Heisenberg’s “postwar attempts to change the historical record.”¹³ Powers, however, downplayed the letters as “enrich[ing] our understanding of one small episode in the story.” Weizsäcker (see figure 4) also echoed his previous statements and told the press that “Bohr’s memory was deeply mistaken.”

The debate about Heisenberg and German nuclear intentions continues to this day. Although Rose died in 2014, Powers continues to cite the Farm Hall transcripts as evidence that Heisenberg “found a way to say no” to building a bomb. And in 2016, the German physicist Manfred Popp emerged and cited the Farm Hall transcripts in support of his argument that the Germans did not know how to build an atomic bomb.¹⁴ Given the terrifying hypothetical of a Nazi atomic weapon, the Farm Hall transcripts will surely continue to draw a constant stream of readers.

What was discussed at Farm Hall?

From Goudsmit to Rose, all parties in the German nuclear debate made two mistakes. First, they read their existing views into the Farm Hall transcripts. Second, they viewed the transcripts as a smoking gun. But the Farm Hall transcripts are not that; they are instead a selective record of conversations among 10 complicated and morally fallible human beings during a stressful period of captivity. In those conversations, the guests touched on topics from many different angles, thereby providing quotes that support divergent interpretations of their intentions vis-à-vis the German nuclear project.

For example, at one point Weizsäcker hinted at the possibility of resistance to the bomb, claiming that “if we had all wanted Germany to win the war we would have succeeded.” Yet at a later point in the transcripts, Bagge said that it was “absurd for von Weizsäcker to say he did not want the thing to succeed. That may be so in his case, but not for all of us.” Similarly, Hahn on one occasion stated that he “would have sabotaged the war if I had been in a position to do so,” but on another occasion Karl Wirtz asserted that “if we had started properly in 1939 and gone all out everything would have been all right,” implying that it would have been possible for the Germans to build a bomb.¹⁵

Contemporary readers can thus find excerpts from the transcripts that fit many differing interpretations of German atomic motives. The situation is only made worse by the fact that the transcripts are not complete and that only the English translation survives. It is no wonder that tendentious authors like Powers and Rose, miles apart in their assessments of Heisenberg and the German atomic project, found them so enticing.

Processing trauma

So, what can be learned from the Farm Hall transcripts? Much can be gleaned from them when they are read in their proper context. As Walker has discussed, the Farm Hall guests were processing four major questions during their internment: Were we Nazis? Did we know how to make atomic bombs? Could Germany have created nuclear weapons under the Nazis? Were we trying to produce atomic bombs?¹⁶

The answers to those questions were different for each of the 10 individuals, and the answers likely changed during and after the war. At Farm Hall, they were working through those issues for the first time. When such issues are finally processed, the result is rarely a coherent narrative. Feelings and emotions often emerge in a jumble. And although the trauma faced by Heisenberg, Weizsäcker, and the others paled in comparison with that felt by the millions who were oppressed or murdered by the Nazi regime, the experience of living through Nazism and being held captive was certainly traumatic. Unsurprisingly, their conversations were discombobulated and fraught with tension.

After two days of fervid conversation, on 8 August 1945, the 10 scientists settled on a memorandum outlining their actions during World War II. The memo notably differed in some respects from aspects of the conversation recorded by the Allies, particularly in the assertion that “it did not appear feasible at the time to produce a bomb with the technical possibilities available in Germany.”¹⁷ Laue, the only physicist interned at Farm Hall who had never worked on the German nuclear project, later termed that the Lesart.¹⁸ If anything, the Farm Hall transcripts demonstrate that the Lesart developed out of the emotional way the guests processed their wartime trauma after hearing about the Hiroshima bombing.

In that sense, the belief that the transcripts are the perfect historical source was not misplaced. But what they truly reveal is how history is processed by humans. Heisenberg’s son Jochen put it well in 2019 when he perceptively noted that the Farm Hall guests were “stumbl[ing] through that complexity” of a historical moment that was “irreversible in its consequences for mankind.” Rather than definitively proving German atomic complicity or resistance, the Farm Hall transcripts illustrate how trauma and guilt are rarely, if ever, processed linearly or rationally.

This article was adapted from “The Farm Hall transcripts: The smoking gun that wasn’t,” Berichte zur Wissenschaftsgeschichte, 2022, doi:10.1002/bewi.202100033.

References

1. M. Walker, German National Socialism and the Quest for Nuclear Power, 1939–1949, Cambridge U. Press (1989); M. Walker, Nature 359, 473 (1992).
2. S. A. Goudsmit, Alsos, Henry Schuman (1947), p. 133.
3. Ref. 2, p. 138.
4. L. R. Groves, Now It Can Be Told: The Story of the Manhattan Project, Harper & Brothers (1962), p. 334.
5. R. Jungk, Brighter than a Thousand Suns: A Personal History of the Atomic Scientists, J. Cleugh, trans., Harcourt, Brace (1958), p. 219.
6. R. Jungk, Trotzdem: Mein Leben für die Zukunft (Nevertheless: My Life for the Future), Carl Hanser Verlag (1993), p. 297.
7. E. Bagge, K. Diebner, in Von der Uranspaltung bis Calder Hall (From Uranium Fission to Calder Hall), Rowohlt (1957), p. 56; E. Bagge, diary (7 August 1945), David Irving Microfilm Collection, Niels Bohr Library and Archives, American Institute of Physics, College Park, MD, microfilm DJ 29, frames 145–59.
8. T. Powers, Heisenberg’s War: The Secret History of the German Bomb, Alfred A. Knopf (1993).
9. P. L. Rose, Heisenberg and the Nazi Atomic Bomb Project: A Study in German Culture, U. California Press (1998), p. 304.
10. E. Bagge, Phys. Bl. 50, 589 (1994).
11. Interview with C. F. von Weizsäcker by D. Hoffmann, H. Rechenberg, and T. Spenger, 3 June 1993, in D. Hoffmann, ed., Operation Epsilon: Die Farm-Hall-Protokolle oder die Angst der Alliierten vor der deutschen Atombombe (Operation Epsilon: The Farm Hall Transcripts, or the Allies’ Fear of the German Atomic Bomb), Rowohlt (1993), p. 344.
12. P. L. Rose, Chronicle of Higher Education, 5 May 2000, p. B4.
13. P. L. Rose, in Michael Frayn’s Copenhagen in Debate: Historical Essays and Documents on the 1941 Meeting between Niels Bohr and Werner Heisenberg, M. Dörries, ed., Office for History of Science and Technology, U. California (2005), p. 85.
14. M. Popp, Ber. Wissenschaftsgesch. 39, 265 (2016), p. 274.
15. J. Bernstein, ed., Hitler’s Uranium Club: The Secret Recordings at Farm Hall, 2nd ed., Copernicus Books (2001), p. 122.
16. M. Walker, Nazi Science: Myth, Truth, and the German Atomic Bomb, Plenum Press (1995), p. 209.
17. Ref. 15, p. 147.
18. M. von Laue to P. Rosbaud (4 April 1959), in ref. 15, p. 351.