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Heisenberg’s Dresden story: A wartime atomic mystery

by Alex Wellerstein, published October 11th, 2013

One of the weirdest stories I’ve come across regarding the Nazis and the atomic bomb is the one that the German physicist Werner Heisenberg told at Farm Hall about being asked about an apparent rumor that the United States was planning to use an atomic bomb against Dresden.

The Farm Hall transcripts reports him telling it several times during his internment, and it changed slightly each time he told it. Here’s the first version:

About a year ago, I heard from Segner from the Foreign Office that the Americans had threatened to drop a uranium bomb on Dresden if we didn’t surrender soon. At the time I was asked whether I thought it possible, and, with complete conviction, I replied: “No.”

In a later version, he says he replied that it was possible — perhaps a face-saving maneuver, since by the second time Heisenberg tells the story, he has now started to believe that the reports of the atomic attack against Hiroshima were accurate.

My initial inclination is to think of this as strange idle chatter amongst a group of interned German scientists. A little bit of rumor-swapping, bragging about being in-the-know and being someone worth consulting. But I don’t think Heisenberg just made it up. That’s not really his style, I don’t think, and he repeated it several times over the course of their six month stay at Farm Hall.

Recently, while looking into some other wartime leaks, I came across an interesting follow-up on this story. The leak in question is a weird one and worth sharing. In August 1944, a German science magazine, the Physikalische Blätter (Physical Newspaper/Gazette/Pages), ran a short, anonymous piece titled “Another Utopia”:¹

Transocean Service transmits a report cabled to “Stockholm’s Tidnigen” from London: “In the United States scientific research for a new bomb is underway. The material is uranium, and if the forces bound in this element could be liberated, explosive forces of so far unimagined power could be created. A 5-kilogram bomb could made a hole one kilometer deep and with a radius of 40 kilometers. In a circle of 150 kilometers all buildings were be smashed.”²

That’s a pretty weird thing to just appear in a German magazine, no? To save you the effort: their math on the energy release is way off by any measure — the damage radius described is well over 100 megatons, which is around what you’d get if you combined 5 kg of uranium with 5 kg of anti-matter (a pure E=mc² conversion), much less if it fissioned with perfect efficiency (which would “only” release 85 kilotons).³ Either they’ve carried a few decimal points incorrectly or they’re just really confused. I suspect the latter.

Was this a “legitimate” leak? That is, did it derive from disclosure of confidential information? It’s hard to tell. The fact that it pinpoints the United States as making an atomic bomb out of uranium seems accurate, but everything else seems to be sketchy and confused. It’s true that the plutonium bomb used only around 6 kg of material… but that almost seems like a coincidence given the rest of what they’re talking about here. I’m inclined to file this under “fantastic atomic energy rumors” which were common even before the discovery of fission.

Werner Heisenberg, later in life

Anyway. The interesting bit comes 20 years later, in 1964. Physikalische Blätter was (and is) still around, and they ran a story on their wartime leak story. Much of it is repetitive fluff, a by-the-book (for 1964) accounting of Allied and German nuclear research. But along with this, they did attempt to track down the origin of the leak — with no success. But they did decide, thoughtfully, to try and assess the impact of the leak by surveying a few of the Farm Hall physicists to see whether they were aware of the “Another Utopia” story.

Otto Hahn wrote back that he “knew nothing” of the article at the time, and added that while they knew that there were people abroad probably working on the subject of atomic bombs, and that the stopping of all publications about the subject probably indicated the work was secret, that nonetheless they didn’t suspect that the United States would actually be able to produce such weapons in time for use in the war. He then suggested that the Physikalische Blätter should get in touch with Heisenberg, since he was more plugged into such matters than Hahn.⁴

And they did get in touch with Heisenberg, whose first response was that he hadn’t seen the article, was surprised to hear about it, suspected it was based on “vague rumors,” but said he would love if they sent him a copy so he could evaluate it further.⁵ They did this, of course, and his second response was the more interesting one. He said that rumors of this sort occurred repeatedly because of articles related to atomic energy that had already been published, and he did not let such rumors occupy him much during the war. But then Heisenberg wrote (my awkward translation — original German is in the footnotes):

Perhaps I should mention here an exception. In the summer of 1944 (probably early July), an aide of Göring’s came to me with a message from a German representative in Lisbon that there was a pronounced American threat against the German government, that an atomic bomb would be dropped on Dresden in the next six weeks if the government did not immediately sue for peace. The exact conditions of where the message came from were not communicated to me. I was asked by Göring’s adjutant if I thought it was possible that the Americans had already created an atomic bomb. I was understandably made very uncomfortable by this question, because of the large responsibility connected to my answer. I said that I thought it was extremely unlikely, but not impossible, for the Americans to have such a weapon at this time, and I tried to explain that the production of the weapon would in any case require an enormous industrial effort, and that I could not imagine that the Americans had already done it.⁶

And so the Dresden atomic bomb rumor raises its head again, no less confounding than before! But here we have a little more information on the source: it is supposedly from an agent in Lisbon, Portugal. Which is interesting.

General Groves is not amused by spies or leaks

Because as Stan Norris communicated to me when I wrote about German espionage efforts, there was a Nazi double-agent in Lisbon who was assigned to learning about the Manhattan Project. Stan has since sent me a “note to file” that General Groves had written about a meeting he had with the Military Policy Committee on June 21, 1944, where he describes this incident and his response to it. In his notes, Groves wrote the following:

This refers to the German agents who came to this country through Portugal, and the messages that were sent back to Germany in their behalf. These people were picked up as soon as they got into the United States and the messages were framed by me. There was considerable argument by my creeps as to these messages. I overruled them and did not deny that certain work was being done. It was pinpointed at certain universities and certain people, none of whom had anything to do with the project. The amount of the work was minimized, and an attempt to convince the Germans that it was an academic effort and that nothing would come of it. The creeps wanted to say that nothing was being done and that checks at various places had indicated that all potential personnel was being used on other work — I think radar.⁷

Ah, so now this gets really interesting, right? Because this coincides very well with the timing of Heisenberg’s supposed query — apparently originating in Nazi agents in Portugal — regarding whether Dresden would be atomic bombed! (And no, I don’t know why he calls whomever he is talking to “creeps.”)

Obviously I don’t have the whole story here, but the geographical and chronological proximity is a rather impressive overlap, is it not? Could something have gone wrong, or gotten scrambled, in Groves’ attempt to manipulate one of the few German atomic espionage attempts? I.e., Groves had wanted to suggest that the American program was small and unimportant; somebody instead reported back that it was massive and almost ready to go. It seems not impossible, though this is admittedly scant evidence. Either way, it’s clear that Groves would have been mighty mad to find out this question was being asked of Heisenberg.

But, here’s the twist. Arguably the exaggerated outcome would have been (and in fact was!) as good an outcome as Groves’ intended minimization, if not a better one! Heisenberg looked at the six-weeks-to-an-atomic-Dresden claim and said, no way — that doesn’t make any sense. He came away from the whole thing convinced it was just ridiculous wartime nonsense. If the report he had gotten was, “do you believe that the only people working on nuclear fission are a bunch of no-names, instead of Bethe and Fermi and Oppenheimer and Wheeler and all of those other physics luminaries we know the Americans have?,” might that not have raised his suspicions even more?

Of course, that doesn’t explain where Dresden, specifically, would have come into the picture. So there’s still something missing here. And it should be noted that Lisbon was a notorious hub of espionage activity for both sides during the war — so it isn’t necessarily the same guy. So some sobriety intrudes.

Dresden after the firebombing, 1945

Lastly, is it possible the Dresden threat could have been real? The Physikalische Blätter story got picked up by the Washington Post, and they got in touch with Richard G. Hewlett, the Atomic Energy Commission’s official historian. He thought Heisenberg’s story was pretty nuts: “I can’t possibly believe there was an actual threat from the U.S. Government.”⁸ This was, obviously, because the US was still a year away from an atomic bomb at the time, and the idea of it being some kind of legitimate, diplomatic threat seems pretty out of character. Though do remember that Roosevelt asked Groves about using the bomb against Germany in December 1944 — so maybe, somewhere, this kind of idea was kicking around inside the heads of some people who knew about the Manhattan Project work but didn’t know how close it was to completion — maybe even someone who was working some kind of diplomatic/espionage backchannel. I don’t know.

As it was, Dresden was of course catastrophically attacked. Over the course of three days in February 1945, some 1,250 Allied heavy bombers pounded the city with incendiaries and high explosives, killing well over 20,000 people and burning the heart out of a city that until that point had been spared the horrors of area bombing. Could Dresden have been kept “pristine” on the theory that it might have been a good atomic bombing target, in the same way that Hiroshima, Nagasaki, Kokura, and Niigata had been? The Physikalische Blätter speculated that maybe this was the case, though there is no evidence that supports this conclusion.⁹ I doubt it, personally — the selection of Dresden as a target has its own trajectory that seems independent of any possible atomic narrative, and the idea that it would have been selected as a possible atomic bomb target as early as the summer of 1944 seems rather far-fetched. It should be noted, as well, that the narrative about the atomic bomb in mid-1960s Germany was very much tinged by the Cold War context; it was a common thread of discussion in both the West and the East that the United States would be willing to throw Germany under the bus if it came to a real confrontation with the Soviets.

Still, it’s an interesting constellation of stories: the leak, Heisenberg’s query, and Groves’ attempt at misinformation. If Groves’ misinformation attempt was really did result in the query to Heisenberg, what tremendous irony that would be: ironic that Groves’ attempt to minimize the effort would result in an exaggerated interpretation; ironic that the exaggerated interpretation would lead to total dismissal by the expert.

“Noch eine Utopie,” Physikalische Blätter 1, No. 8 (1944), 118. I was surprised to find all of PB online and without a paywall. This particular article is appended to a longer report on “Science and War.” [↩]
“Transozean-Innendienst verbreitet eine Nachricht, die sich “Stockholms Tidningen” aus London melden läßt: “In den Vereinigten Staaten werden wissenschaftliche Versuche mit einer neuen Bombe ausgeführt. Als Material dient Uran, und wenn die gebundenen Kräfte in diesem Element frei würden, dann könnten Sprengwirkungen· von bisher nicht geahnter Kraft erzeugt werden. Eine 5-kg-Bombe könnte dann ein Loch von 1 km Tiefe und 40 km Radius hervorbringen. In einem Umkreis von 150 km würden alle festen Gebäude in Trümmer gehen.” [↩]
The rule of thumb is that the completely fissioning of a kilogram of fissile material produces about 17 kilotons of yield. [↩]
“Ich wußte gar nichts von dem Inhalt des Artikels im Augustheft 1944 der Physikalischen Blätter, und so möchte ich daraus schließen, daß er mir auch damals nicht bekannt war. Wir alle waren natürlich während des Krieges der Meinung, daß man im Ausland, vor allem in Amerika, wohl an einer Herstellung von Atombomben arbeiten wird, denn es wurden ja auch in Deutschland Vorversuche darüber gemacht mit dem Versuch der Aufstellung eines Atomreaktors. Und da nach Kriegsanfang alle Publikationen aus dem Gebiete aufhörten, schlossen wir natürlich, daß im Ausland geheime Arbeiten gemacht würden. Andererseits glaubte keiner von uns, daß während der Kriegszeit eine Atombombe fertiggestellt werden könnte. Ich erinnere mich an das Erstaunen, das wir alle hatten, als wir von der Bombe im August 1945 in englischer Gefangenschaft erfuhren. Da Prof. Heisenberg der Vorsitzende des sogen. Uran-Vereins war, also die Arbeiten zur Herstellung eines Kernreaktors geleitet hat, ist wohl Herr Heisenberg die beste Quelle, zu erfahren, ob jemand von uns die Mitteilung in den Phys. Blättern kennt.” Otto Hahn, quoted in E. Brüche, “Was wußte man 1943/44 in Deutschland von der Atombombe?” Physikalische Blätter 20, No. 5 (1964), 220-225, on 222. [↩]
“Sie schreiben davon, daß in den Phys. Blättern bereits 1944 eine Notiz über die amerikanischen Versuche mit Atombomben erschienen sei. Dies ist mir völlig neu, aber zugleich interessant und unbegreiflich; denn die ersten amerikanischen Atombombenversuche haben ja bekanntlich im Frühjahr 1945 stattgefunden. Es kann sich also eigentlich nur um ziemlich vage Vermutungen gehandelt haben. Ich wäre Ihnen sehr dankbar, wenn Sie mir eine Kopie jenes Artikels in den Phys. Blättern zukommen lassen könnten; dann kann ich besser beurteilen, ob ich diesen Artikel jemals gesehen habe und wie ich darauf reagiert habe.” Werner Heisenberg, quoted in E. Brüche, “Was wußte man 1943/44 in Deutschland von der Atombombe?” Physikalische Blätter 20, No. 5 (1964), 220-225, on 222. [↩]
“An die von Ihnen erwähnte Notiz in den Phys. Blättern aus dem Jahr 1944 konnte ich mich nicht mehr erinnern, aber Gerüchte dieser Art sind – schon aufgrund des Flüggeschen Artikels in den “Naturwissenschaften” – immer wieder aufgetreten und haben mich daher nicht allzu sehr beschäftigt. Vielleicht sollte ich hier eine Ausnahme erwähnen. Im Sommer 1944 (wahrscheinlich Anfang Juli) kam einmal der Adjutant von Göring zu mir mit der Mitteilung, es sei über die deutsche Vertretung in Lissabon eine amerikanische Drohung gegen die deutsche Regierung ausgesprochen worden, es werde innerhalb der nächsten sechs Wochen eine Atombombe über Dresden abgeworfen werden, wenn die Regierung nicht in irgendeiner Art um Frieden bäte. über den genauen Inhalt der Bedingungen wurde mir nichts mitgeteilt. Ich wurde von dem Adjutanten Görings gefragt, ob ich es für möglich hielte, daß die Amerikaner bereits über eine Atombombe verfügten. Mir war diese Frage begreiflicherweise sehr unangenehm, weil mit der Antwort auf jeden Fall eine große Verantwortung verbunden war. Ich habe dann gesagt, daß ich es zwar für außerordentlich unwahrscheinlich, aber nicht für völlig unmöglich hielte, daß die Amerikaner zu diesem Zeitpunkt über eine solche Waffe verfügten, und habe versucht zu erklären, daß die Herstellung der Waffe auf jeden Fall einen enormen industriellen Aufwand erfordern müßte, von dem ich mir nicht denken könnte, daß die Amerikaner ihn schon geleistet hätten.” Ibid. An article on uranium fission by Siegfried Flügge appeared in Die Naturwissenschaften in June 1939; Heisenberg cites this as the reason for all of the speculation. Flügge himself was asked about the “Another Utopia” article as well and he responded with a diatribe about how nobody credits him for anything. [↩]
Leslie Groves, Notes on the Military Policy Committee of June 21, 1944 (undated, but prior to 1964), Leslie R. Groves Papers, National Archives and Records Administration, RG 200, Entry 7530M, Box 4, “Working Papers.” Courtesy of Robert S. Norris. [↩]
Howard Simons, “Were We Vulnerable: Swedish Report in World War II Tipped U.S. A-Bomb Hand,” Washington Post (27 December 1964), E3. Simons’ story butchers many of the facts, including getting the nationality of Physikalische Blätter wrong (which PB took issue with in its reprinting of it), and even misspells Hewlett’s name. [↩]
“Dresden – Schicksal und Warnung,” Physikalische Blätter 21, no. 4 (1965), 196. [↩]

Tags: 1940s, 1960s, Espionage, Germany, Leaks, Leslie Groves, Manhattan Project, Speculation
Posted in Redactions | This post has footnotes | 33 Comments »

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Would the atomic bomb have been used against Germany?

by Alex Wellerstein, published October 4th, 2013

If the atomic bomb had been ready earlier in World War II, would it have been used against Nazi Germany? This is one of the great atomic “what if’s” — a hypothetical, counter-factual historical question that obviously can’t be answered because that’s not how history worked out, we can’t reshuffle the past around, and so on. Anything overtures in such a direction are just speculation. But it can be informed speculation — and, more importantly, it can highlight little-known aspects of history. And that, in my mind, makes it worth indulging in, at least on a blog.

The question is an interesting one for numerous reasons. At its heart, it gets at the question of how contingent all of this was. The primary factor that determined when the first atomic bombs were ready for use was when the serious program of their production started. If the Americans had been convinced in 1940, rather than 1941, that an atomic bomb was worth seriously pursuing, then the Gadget might have been ready by July 1944, not July 1945. Could they have been convinced that early on? I see no reason why not — the British scientists had drawn that conclusion by then.

Allied troops disassembling the German experimental research reactor at Haigerloch.

Up until early 1944, the bomb was still talked about as if it were going to be a deterrent against Germany. By August 1943, for example, Vannevar Bush was still reporting to Roosevelt that the Germans might be ahead, or at least neck-and-neck in the “race” for the bomb: “This may result in a situation where it will be necessary for us to stand the first punishing blows before we are in a position to destroy the enemy.” By early 1944, Groves had decided that the Germans having a bomb was “unlikely,” but that it still needed to be held out as a possibility. By late 1944, it was clear, from the Alsos mission, that Germany was nowhere near an atomic bomb — and indeed, they soon learned that the German program was in 1945 not even as far as where the Americans had gotten by the end of 1942. I put this out just as context for their thinking. Over the course of late 1943 through 1944, the bomb shifted from being a deterrent to a first-strike weapon — a weapon that was meant to be used, not held in reserve. So who would it strike?

The very earliest discussion of targets of any sort was held in May 1943. As the last item of a much longer meeting, talking about all sorts of other matters (like spreading around fake stories about what was going on at Los Alamos, E.U. Condon’s resignation from the project, and construction of the various enrichment and production plants), a group composed of Groves, Vannevar Bush, James B. Conant, Admiral William Purnell, and Major General Wilhelm Styer had this discussion:

The point of use of the first bomb was discussed and the general view appeared to be that its best point of use would be on a Japanese fleet concentration in the Harbor of Truk. General Styer suggested Tokio but it was pointed out that the bomb should be used where, if it failed to go off, it would land in water of sufficient depth to prevent easy salvage. The Japanese were selected as they would not be so apt to secure knowledge from it as would the Germans.¹

This has sometimes been cited as evidence that Japan was “always” the target. Personally, I think this seems like too loose of a discussion to draw big, concrete conclusions from. It was still over two years before the first atomic bomb would be ready, and, again, it is tacked on to a much longer meeting that is concerned with much more basic, much more practical things, like whether J. Robert Oppenheimer will get an administrative assistant assigned to him. But, still, it’s a data point. Note that the context, here, of choosing Japan over Germany is reflective of how uncertain they are about the bomb itself: they are worried that the first one will be a complete dud, and so their choice here is that if a dud were to land in Germany, it would be more dangerous thing than if it were to land in Japan.

Note that “the Harbor of Truk” (Chuuk Lagoon) is not a target on the Japanese home islands — it is in Micronesia, far south of the Japanese mainland, north of New Guinea. During World War II it was the Japanese equivalent of Pearl Harbor. It was a purely military, tactical target, not a strategic one. And by the time an atomic bomb was ready, it had been made irrelevant by Allied attacks and isolation (though it was still under Japanese occupation).

The first concrete discussion of targets came in the spring of 1945. These are the famous “Target Committee” meetings at Los Alamos which discussed what kind of target criteria they were using, what cities might fit it, and so on. Grim business, but entirely focused on Japan, in part because by that point it was clear that Germany’s defeat was imminent.

An elderly General Groves. This is from a fairly later period — 1967 or so. From the AIP Emilio Segrè Visual Archives, George Tressel Collection.

Is there any evidence that anyone in power would have considered atomic bombing Germany, though, had they the ability? The only insight I’ve found on this comes from a postwar interview that General Groves gave, sometime in the early 1960s:²

REPORTER: General Groves, could we go back for a minute. You mentioned in your book [Now it Can Be Told] that just before the Yalta Conference that President Roosevelt said if we had bombs before the European war was over he would like to drop them on Germany.³ Would you discuss this?

GROVES: At the conference that Secretary Stimson and myself had with President Roosevelt shortly before his departure, I believe it was December 30th or 31st of 1944, President Roosevelt was quite disturbed over the Battle of the Bulge and he asked me at that time whether I could bomb Germany as well as Japan. The plan had always been to bomb Japan because we thought the war in Germany was pretty apt to be over in the first place and in the second place the Japanese building construction was much more easily damaged by a bomb of this character than that in Germany. I urged President Roosevelt that it would be very difficult for various reasons.

The main one was that the Germans had quite strong aerial defense. They made a practice, as every nation does, that when a new plane came into the combat area, that they would run any risk that they could to bring such a plane down so that they could examine it and see what new ideas had come in so that they could make improvements and also would know the characteristics of the plane so that they could prepare a better defense against it. We had no B-29’s in Europe. If we had sent over a small squadron or group as we did against Japan of this type, everyone of them would have been brought down on the first trip to Germany. If they hadn’t been, it would have been through no lack of effort on the part of the Germans.

The alternative would be to bring a large number of B-29’s over to to England and that would have been a major logistical task and the other possibility would have been to have used a British plane which would not have been a bit pleasing to General Arnold and also would have created a great many difficulties for our general operation because then it would be an Allied operation with the United States furnishing the bombs and everything connected with it but using a British plane and a British crew to actually drop the bomb and it would have raised a tremendous number of difficulties.

And difficulties like that — while you say you should be able to handle that — you can but in a project of this character there are so many little things, each one of them key, that you can’t afford to throw any more sand into the wheels that you can help.

The bombing of Germany with atomic bombs was, I would say, never seriously considered to the extent of making definite plans but on this occasion I told the President, Mr. Roosevelt, why it would be very unfortunate from my standpoint, I added that of course if the President — if the war demanded it and the President so desired, we would bomb Germany and I was so certain personally that the war in Europe would be over before we would be ready that you might say I didn’t give it too much consideration.

Now this is an interesting detail, is it not — that FDR himself was interested in whether they could drop an atomic bomb on Germany? One has to always question postwar recollections, especially the General’s, but this has the ring of authenticity to it. I don’t think Groves would fabricate memories of conversations with Roosevelt. At this meeting, Groves had thought that the first uranium bomb (Little Boy) would be ready by late July, and that the first plutonium bomb would be ready by early August — far too late for use in the European war. But it is worth contemplating Roosevelt’s intentions. Did he really want to drop this bomb, or was he trying to figure out what exactly the USA’s chips were before entering into discussions with the Soviets? Would Roosevelt have made the same concessions to the Soviets that he ended up making, had he thought the US had an atomic bomb at the ready? Would he have insisted that the Soviets enter the Pacific war? More hypotheticals than I can deal with, but it does add an interesting wrinkle to the discussion.

The B-17 bomber (left) and the B-29 bomber (right). Source.

Groves’ argument against using a bomb in the European theatre is also interesting. Essentially he is saying that the choice not to deploy B-29s in Europe, and the choice of the B-29 as the weapon for the atomic bomb (a decision made in late 1943), had profound practical consequences. It is easy to forget that the first atomic bombs could not be dropped out of just any old plane. They were huge by the standards of World War II: the Fat Man bomb was a single, 10-foot-long, 5-foot-wide weapon that weighed over 5 tons. Neither the B-17 nor the B-24 could carry such a load in weight alone, much less in one fat bomb. The Little Boy boy bomb was just as long, weighed a little less, and did not have as large a diameter. It was also a bit over the maximum load ever carried by those other planes. The British Avro Lancaster bomber could have carried Little Boy, though — the Tall Boy and Grand Slam bombs were larger than Little Boy, though with much smaller diameters than Fat Man. My guess is that the Lancaster’s bay was too narrow for Fat Man.⁴

Does one buy Groves’ reasons? Part of me is suspicious that his justification has the feel of a post facto justification to it — it’s just a little too thought out for a quick reply to Roosevelt. If I were to guess, it was the fact that he didn’t expect the bombs to be ready anytime soon, and didn’t want the obligation of trying to get one ready for use against Germany, that really was the reason for him not wanting FDR to think that the bomb might be ready for that piece of the war. Having one ready to drop on Japan by August 1945 proved to be a tough job as it was.

Was racism a factor? This sometimes gets asked as well. One of the tricky things about racism is that it only rarely factors into reasoning explicitly. I’ve seen nothing in the discussions of the people in charge of target selection that make me think that racism played any kind of overt role in the decisions they made — at least, in the sense that they would have dropped the bomb on the Japanese but would not have dropped it on the Germans. It doesn’t mean it didn’t, of course — just that I haven’t seen any real evidence of it. This is an entirely separate issue from whether racist dehumanization was encouraged for the populace and the troops (it obviously was). But, again, I don’t see any evidence to support the idea that the Americans would not have used atomic weapons against the Germans because they were whites, but would have used them against the Japanese because they were not. The Allies clearly were willing to massacre German civilians, as they did drop firebombs on several German cities, though that obviously does not tell the whole story.

So what’s the take-away answer? The long and short of it is, of course, that they didn’t have the bombs ready to use in the European theatre, knew they wouldn’t from fairly early on, and so never took the time to try and clarify the logistical issues that would have made it practicable. But Roosevelt’s question to Groves does leave open the possibility that they might have done it, if all of those things had turned out differently.

Minutes of the Military Policy Meeting (5 May 1943), Correspondence (“Top Secret”) of the Manhattan Engineer District, 1942-1946, microfilm publication M1109 (Washington, D.C.: National Archives and Records Administration, 1980), Roll 3, Target 6, Folder 23, “Military Policy Committee, Minutes of Meetings.” [↩]
Leslie R. Groves interview with Fred Freed (n.d., ca. 1963), National Archives and Records Administration, RG 200, Box 4, “Groves, Leslie.” [↩]
“It was at the same conference that Mr. Roosevelt informed me if the European war was not over before we had our first bombs he wanted us to be ready to drop them on Germany.” Groves does not elaborate on this in the book at all. Leslie Groves, Now it Can Be Told (New York: Harper, 1962), 184. [↩]
And the Gadget was pretty snug inside the Fat Man ballistic casing — I don’t see them reducing the diameter. [↩]

Tags: 1940s, Counterfactuals, Franklin D. Roosevelt, Germany, Leslie Groves, Manhattan Project
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The final switch: Goldsboro, 1961

by Alex Wellerstein, published September 27th, 2013

The threat of nuclear weapons accidents isn’t a new one. Even in 1945, Los Alamos physicists sweated when contemplating all that could possibly go wrong with their bombs, if they went off at the wrong place or the wrong time. Or didn’t go off at all. That’s the bind, really: a nuclear state wants a weapon that always goes off exactly when you tell it to, and never goes off any other time. That’s a hard thing to guarantee, especially when the stakes are so high in both directions, and especially since these two requirements can be directly in tension.

I recently heard Eric Schlosser give that elegant formulation at a talk he gave last week in support of the release of his new book, Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety. I haven’t had a chance to read the book, yet (it’s currently en route), but I’m looking forward to it. I read Schlosser’s Fast Food Nation a decade (!) ago and found it completely eye-opening. But I went to his talk last week not sure what to expect. From McDonald’s to nuclear weapons accidents? Stranger things have happened, but I worried that maybe he would take the “easy” route with regards to the accidents, not bothering to learn to nitty-gritty technical details that let one talk about such things sensibly, or, at the very least, sensationalize the findings. So I was pretty pleased to find that neither seemed to be the case. Schlosser has seriously done his homework, spending 6 years digging through records, FOIAing documents, and interviewing weapons designers. His discussion of the risks seemed right on the mark so far as I could tell — they don’t need to be exaggerated one bit to be perfectly horrifying. He answered questions expertly, even a tough, devil’s-advocate one from Hugh Gusterson. So I’ve been looking forward to reading the full book.

Last week, the Guardian released a new document, obtained by Schlosser through a FOIA request, regarding one particular accident, the 1961 crash of a B-52 near Goldsboro, North Carolina, which resulted in the jettisoning of two Mark-39 hydrogen bombs. The document in question is a government nuclear expert’s evaluation of a popular account of the Goldsboro accident, in which he finds some major errors (like overstating the yield of the bomb), but ultimately concludes that at least one of the bombs was, in fact, pretty damned close to accidental detonation: “one simple, dynamo-technology, low voltage switch stood between the United States and a major catastrophe … It would have been bad news – in spades.”

The bomb in question, stuck in the mud.

I’ve been watching how the above document has been discussed by people on the web. The most interesting response has been people saying, “I thought that bomb lacked a nuclear core?” You know that there have been too many nuclear weapons accidents when people start getting them confused with one another. The missing-bomb-that-maybe-lacked-a-core is the 1958 Tybee bomb, where a Mark-15 hydrogen bomb was lost near Savannah, Georgia. Different bomb, different day.

The other response I commonly saw was one that assumed that any such fears of a bomb going off accidentally were exaggerated. Now this is kind of an interesting response. For the one thing, they’re discounting a contemporary, internal, once-classified evaluation made by a relevant expert. In exchange, they’re parroting either general skepticism at the idea that a nuclear weapon could technically be unsafe, or they are parroting a standard line about how hard it is to set off an implosion bomb accidentally, because all of the lenses need to detonate at exactly the same time. Which is sometimes the right approach (though not all American bomb designs were “one-point safe” — that is, there were designs that ran a real risk of producing a nuclear yield even if just one of the explosive lenses accidentally fired), but in this case, it’s entirely irrelevant, for reasons I’ll explain below.

I’ve been in touch with Schlosser since the talk, and he shared with me a video he had (somehow) gotten his hands on produced by Sandia National Laboratory (the weapons lab that specializes in making bombs go off at just the right moment) about the Goldsboro accident. He’s put it up on YouTube for me to share with you. It is only a few minutes long and worth the watch.

I love the CGI — “all the sudden, now that weapon system is free.” The bomb looks so… liberated. And the part at the end, where they talk about how they had plenty of opportunities for future data, because there were so many accidents, is wonderfully understated. But the stuff that really hits you in your gut is the description of exactly what happened:

“All of the sudden now that weapon system [the Mk-39] is free. As the weapon dropped, power was now coming on, and the arming rods were pulled, the baroswitches began to operate.¹ The next thing on the timing sequence was for the parachute to deploy. When it hit the ground, it tried to fire.” “There was still one safety device that had not operated. And that one safety device was the pre-arming switch which is operated by a 28 volt signal.” “Some people could say, hey, the bomb worked exactly like designed. Others can say, all but one switch operated, and that one switch prevented the nuclear detonation.” “Unfortunately there had been some 30-some incidents where the ready-safe switch was operated inadvertently. We’re fortunate that the weapons involved at Goldsboro were not suffering from that same malady.”

What’s amazing about the above, in part, is that everything in quotation marks is coming from Sandia nuclear weapons safety engineers, not anti-nuclear activists on the Internet. This isn’t a movie made for public consumption (and I’ve been assured that it is not classified, in case you were wondering). It’s a film for internal consumption by a nuclear weapons laboratory. So it’s hard to not take this as authoritative, along with the other aforementioned document. Anyone who brushes aside such concerns as “hysterical” is going to have to contend with the fact that this is what the nuclear weapons designers tell themselves about this accident. Which is pretty disconcerting.

There are further details in another document sent to me by Schlosser, a previously-classified review of nuclear weapons accidents from 1987 that clarifies that one of the reasons the Goldsboro bomb in particular almost detonated was because of the way it was tossed from the aircraft, which removed a horizontally-positioned arming pin. That is, an arming pin was supposed to be in a position that it couldn’t be removed accidentally, but the particulars of how violently the aircraft broke up as it crashed were what armed the bomb in question. The other bomb, the one whose parachute didn’t fire, just had its HE detonate while it was in the mud. From the 1987 review:

Before the accident, the manual arming pin in each of the bombs was in place. Although the pins required horizontal movement for extraction, they were both on a lanyard to allow the crew to pull them from the cockpit. During the breakup, the aircraft experienced structural distortion and torsion in the weapons bay sufficient to pull the pin from one of the bombs, thus arming the Bisch generator.² The Bisch generator then provided internal power to the bomb when the pullout cable was extracted by the bomb falling from the weapons bay. The operation of the baroswitch arming system,³ parachute deployment, timer operation,⁴ low and high voltage thermal batteries activation, and delivery of the fire signal at the impact by the crush switch all followed as a natural consequence of the bombing falling free with an armed Bisch generator. The nonoperation of the cockpit-controlled ready-safe switch prevented nuclear detonation of the bomb. The other bomb, which free-fell, experienced HE detonation upon impact. One of the secondary subassemblies was not recovered.⁵

The secondary subassembly is the fusion component of the hydrogen bomb. Normally I would not be too concerned with a lost secondary in and of itself, because bad folks can’t do a whole lot with them, except that in this particular bomb, the secondary contained a significant amount of high-enriched uranium, and lost HEU is never a good thing. The government’s approach to this loss was to get an easement on the land in question that would stop anyone from digging there. Great…

From the video, I was also struck by the picture of the ready-safe switch then employed. I’d never seen one of these before. Presumably “S” means “safe” and “A” means “armed.” It looks ridiculously crude by modern standards, one little twirl away from being armed. This little electronic gizmo was all that stood between us and a four megaton detonation? That’s a wonderful thing to contemplate first thing in the morning. Even the later switches which they show look more crude than I’d prefer — but then again, probably all 1950s and 1960s technology is going to look crude to a modern denizen. And again, just to reiterate, we’re not talking about “merely” accidentally igniting the explosives on the primary bomb — we’re talking about the bomb actually sending a little electrical charge through the firing circuit saying “Fire!” and starting the regular, full-yield firing sequence, stopped only by this little gizmo. A little gizmo prone to accidentally firing, in some of the bombs.

Lest you think that perhaps Sandia overstates it (which seems rather unlikely), take also the testimony of Secretary of Defense Robert McNamara into account. In January of 1963, McNamara explained at a meeting between the Defense and State Departments that he was opposed to Presidential pre-delegation of nuclear weapons in part because of the danger of accidental detonation — either ours or the Soviets’. In the meeting notes, posted some time back by the National Security Archive and forwarded to me by Schlosser, McNamara’s participation is listed as follows:

Mr. McNamara went on to describe the possibilities which existed for an accidental launch of a missile against the USSR. He pointed out that we were spending millions of dollars to reduce this problem to a minimum, but that we could not assure ourselves completely against such a contingency. Moreover he suggested that it was unlikely that the Soviets were spending as much as we were in attempting to narrow the limits of possible accidental launch. He went on to describe crashes of US aircraft[,] one in North Carolina and one in Texas, where, by the slightest margin of chance, literally the failure of two wires to cross, a nuclear explosion was averted.

This one’s interesting because it embeds these accidents in a context as well — the possibility of either us, or the Soviets, accidentally launching a nuke and wondering if a full-scale nuclear exchange has to follow. It’s not quite Strangelovian, since that would require a rogue commander, but it is very Fail-Safe.

As to what the Goldsboro blast would look like, the only time we tested this warhead at full yield was the shot “Cherokee” at Operation Redwing, in 1958. It was a pretty big boom, far more impressive than some of the Hiroshima shots that have been posted along with the Goldsboro story:

And, of course, you can use the NUKEMAP to chart the damage. I’ve added the W-39 warhead to the list of presets in NUKEMAP2, using 4 megatons as the yield (the tested yield was 3.8 megatons, though the W-39 is often stated as an even 4. I rounded up, just because quibbling over 200 kilotons seemed pointless), and a fission fraction of 55%.⁶ It’s a pretty big explosion, with a fallout plume capable of covering tens of thousands of square miles with hazardous levels of contamination (and nearly a thousand square miles with fatal levels). Note that the Cherokee test was a true airburst (the fireball didn’t touch the ground), and so didn’t generate any significant fallout. The Goldsboro bomb, however, was meant to operate on impact, as a surface burst, and would have created significant fallout.

Again, one doesn’t have to exaggerate the risks to find it unsettling. The bomb didn’t go off, that final switch thankfully did work as intended. But that’s cold comfort, the more you learn about the accident. Our current nuclear weapons are much safer than the Mk-39 was, back in 1961, though Schlosser thinks (following the testimony of experts) there are still some unsettling aspects about several of our weapons systems. If we are going to have nukes, he reasons, we should be willing to spend whatever it costs to make sure that they’ll be safe. That seems to me like an argument guaranteed to appeal to nobody in today’s current political climate, with the left-sorts wanting no nukes and no modernization, and the right-sorts not really wanting to talk about safety issues. But I’ll get to that more another day, once I’ve read the book.

If that bomb had gone off, we’d speak of “Goldsboro” as a grim mnemonic, in the same way that we do “Chernobyl” today. One wonders how that would have changed our approach to nuclear weapons, had the final switch not held strong.

The “arming rods” were pull-out switches that would activate when the weapon left the bomb bay. The baro(meter) switches were pressure sensitive switches that would make sure the bomb was nearing the appropriate height before starting the next sequence of arming. In the World War II bombs, the next stage in the sequence would be to consult radar altimeters to check the precise distance from the ground. The Goldsboro bombs were set to go off on ground impact. [↩]
A Bisch generator, as the context implies, is an electrical pulse generator. [↩]
Again, a pressure-sensitive switch that tried to guarantee that the bomb was roughly where it was supposed to be. [↩]
Timer switches were often used to make sure that the bomb cleared the aircraft before seriously starting to arm. [↩]
R.N. Brodie, “A Review of the US Nuclear Weapon Safety Program – 1945 to 1986,” SAND86-2955 [Extract] (February 1987). [↩]
Chuck Hansen, in his Swords of Armageddon, estimates that shots Cherokee and Apache of Operation Redwing had an average fission fraction of 55%, but isn’t able to get it any more precise than that. Given what I’ve read about the bomb — that it used an HEU secondary, for example — I would expect it to be at least 55%, if not more. It seems like a pretty “dirty” weapon, emphasizing a big yield in a relatively small package over any other features. See Chuck Hansen, Swords of Armageddon, V-224 (footnote 325). [↩]

Tags: 1960s, Accidents, Bad ideas, Bomb design, Books, H-bomb
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The worst of the Manhattan Project leaks

by Alex Wellerstein, published September 20th, 2013

We live in an era where the press regularly rejoices in printing “national security secrets,” via leaks, as an evidence of its “watchdog” status. This isn’t exactly a new thing, of course. Press leaks and investigations have been around for quite a long time, and ever since the example of Woodward and Bernstein, this has become the ultimate symbol of journalistic power and access. But it does feel like it has accelerated somewhat in the last decade, both in terms of frequency and magnitude of such “antagonistic leaks” (as opposed to, say, “official leaks” — the kind that are secretly sanctioned for whatever reason). I’ve sometimes heard people suggest that were the press like this during World War II, things like the secret of the atomic bomb could never have been kept as well as they were. And while there is something to that, in the sense that American journalists were far more cooperative and acquiescent during the 1940s, it also projects a rosier picture backwards than ever truly existed. Even during the Manhattan Project, there were copious leaks. Some small, some huge.

Saturday Evening Post, November 1945 — one of the postwar articles lauding the Manhattan Project as the “best-kept secret,” or, in this case, “the big hush-hush.”

During World War II, the United States had a program of voluntary press censorship, coordinated by the Office of Censorship. It was, as stated, voluntary: there were no fines or threats attached to it, just stern official rebuke. It lacked “teeth.” It worked primarily by the Office of Censorship publicly releasing long lists of prohibited topics, and occasionally trying to squelch violating stories before they were syndicated. As such, it was a little clunky, something that usually went into effect after the fact.

The worst violation came in March 1944. John Raper, a reporter for the Cleveland Press, while on vacation in New Mexico, somehow stumbled upon one of the biggest, most secret stories of the day. Below I reprint the entirety of the article — it nearly speaks for itself, both in its security violations and its strange rambling nature. Some commentary follows; minor comments are in the footnotes. The images have been ordered to correspond with the text, not necessarily how they were laid out on the page.¹

THE CLEVELAND PRESS – MONDAY, MARCH 13, 1944

Forbidden City

Uncle Sam’s Mystery Town Directed by “2nd Einstein”

Jack Raper, Press columnist, has returned to Cleveland following a vacation in New Mexico, where he found the following story.

By JOHN W. RAPER

SANTA FE, N.M. — New Mexico has a mystery city, one with an area from eight to 20 square miles, according to guesses. It has a population of between 5000 and 6000 persons, not more than probably half a dozen of whom can step outside of the city except by special permission of the city boss. He grants permission only in the most exceptional circumstances and under the most rigid conditions. And it is even more difficult for a non-resident to enter than for a resident to leave.²

Commonly known as Los Alamos, the place is a thoroughly modern city. It has fine streets, an electric light plant and waterworks with capacity for a city twice as large as Los Alamos, a service department that really services, public library, high, grade, and nursery schools; recreation centers, hospital, apartment houses, cottages, dance hall, an enormous grocery, refrigeration plant, factories and jail.

If you like mysteries and have a keen desire to solve one, here is your opportunity to do a little sleuthing, and if you succeed in learning anything and then making it public you will satisfy the hot curiosity of several hundred thousand New Mexicans.

But you might as well be informed that you will fail and the chances are thousands to one that you will be caught and will be thrown into the hoosegow or suffer a worse fate.³

A Free Country, But —

Of course, this is a free country and you can go where you please — if you are willing to sleep in the smoking car aisle or breathe the exhalations of your fellow sardines packed in a bus. But forget all about that sort of nonsense.

If you have any idea that you can employ a battery of eminent constitutional lawyers and go into court and that eventually the Supreme Court of the United States will decide the case in your favor if the lower courts decide against you, forget about that, too. you would be wasting your time and burning up any money you paid to the lawyer, for the man who owns this city has too much money and too much power in such a legal action.

This city’s site, or at least part of it, at once time was occupied by a private school for boys,⁴ and is not far from the village of Los Alamos, which is 53 miles almost due east from Santa Fe, the state capital.⁵ It is in one of the most interesting sections of New Mexico. It has scenery enough for a whole state — peaks and peaks and more peaks, and cliffs and colors that dim the rainbow.

Not far away are the Indian villages occupied by the finest kind of Indians, intelligent, industrious, friendly, skilled in the production of art objects, many of them graduates of Indian schools.

Cliff Dwelling Remnants

Within a short distance are the remnants of cliff dwellings, excavated ruins of pueblos centuries old, so old that men who have made scientific studies of them will say, when talking of their ages, “They may be,” “Probably,” “Estimates vary,” “We are pretty certain, but—.”

Shortly after the man who thinks he is going to the mystery city of Los Alamos reaches the level on which it is built, he will see, if he looks into the windshield mirror, a man following him on a motorcycle not many feet behind the car and he will be in the same position when the gate is reached. The instant the car stops there is a man directly in front of it and a man on each side. The three men are in military uniform and each has a rifle.

Then you realize that the owner of this strange city is Uncle Sam and you make no kind of protest and answer questions politely. If you have gone through all of the preliminary red tape previously and have been notified that you will be admitted, the men at the gate will know all about you and there will be little delay after you show the necessary papers.

Escorted by 2 Jeeps

You will be escorted to the office of the man whom you are to meet, escorted by two jeeps, one in front and one behind your car, men in each jeep armed with rifles. En route you will notice that the city is fenced in and that mounted soldiers patrol it and you will see scores of buildings.

When you transact your business you will be carefully escorted out of the city, taking the same route as when you entered. If you are a New Mexican and on your return to your home town it becomes known that you were in Los alamos everybody will ask, “What did you see?” The answer will be, “Nothing.” And if anyone asks, “Did you learn what is going on there?” the answer will be, “I don’t know a bit more about it than I did before I went.” Both answers will be true.

Uncle Sam has placed this in charge of two men. The man who commands the soldiers, who sees that the garbage and rubbish are collected, the streets kept up, the electric light plan and the waterworks functioning and all other metropolitan work operating smoothly is a Col. Somebody.⁶ I don’t know his name, but it isn’t so important because the Mr. Big of the city is a college professor, Dr. J. Robert Oppenheimer, called “the Second Einstein” by the newspapers of the west coast.⁷

Residents Must Stay

Dr. Oppenheimer is a Harvard graduate, attended Cambridge a year, received a Ph.D. from Gottingen University, Germany; is professor of physics at the University of California and the California Institute of Technology, and is a “fellow” of too many organizations to enumerate.⁸

It is the work of Prof. Oppenheimer and the hundreds of men and women in his laboratories and shops that makes Los Alamos such a carefully guarded city. All the residents will be oblige to remain there for the duration and for six months thereafter and it seems quite probable that many of them don’t know much more about what is being done than you do.⁹

It is gossip that no one mechanic is permitted to finish a piece of work. He starts to make something and it is passed at a certain point in its production to another, who goes a little further with the work and passes it to another and so on until the article is finished.¹⁰

One of the public’s guesses is that nothing but research is done.

Thousands believe the professor is directing the development of chemical warfare, so that if Hitler tries poison gas Uncle Sam will be ready with a more terrifying one.¹¹

Tell of Huge Explosions

Another widespread belief is that he is developing ordnance and explosives. Supporters of this guess argue that it accounts for the number of mechanics working on the production of a single device and there are others who will tell you tremendous explosions have been heard.¹²

The most interesting story is that Prof. Oppenheimer is working on a beam that will cause the motors to stop so that German planes will drop from the skies as though they were paving blocks.¹³

In support of this there are stories of the experiences of automobile drivers in the vicinity of Los Alamos. According to these their radios and motors stopped suddenly at the same instant and after 15 or 20 minutes suddenly began to operate as usual.¹⁴

Names of the drivers are frequently given, but when I asked “Did any of them tell you, or did you get it secondhand?” the answer invariably was, “Well, he didn’t tell me. A friend of mine told me about it.”

And if you say, “Did you ask your friend if the driver who had the experience told him?” The answer is generally, “Well, I didn’t ask that question.”

One of these days Prof. Oppenheimer may tell the newspapers about what he has done at Los Alamos, there may be another now-it-can-be-told book or the secretary of war may hand out the report made to him. And who knows but that the eminent physicist may deliver an address at the Cleveland City Club or the Rotary Club?

If you’d rather see it in the original spread, uploaded here is my copy of it from the archives. Note the original is a photostat and has black/white reversed, which is why it is a bit washed out after photographing (shop talk: it is very hard to photograph old photostats because they are on glossy paper and thus reflective, so you have to take pictures of them under shadows).

Why do I consider this the worst? Not because it says, in any straight terms, that atomic bombs are being made. But look at the suggestions it is giving to potential spies:

It identifies (with some geographical error) the name and location of an obviously classified scientific/military facility
It gives an approximate and plausible size of the facility, which gives some hint of its importance
It emphasizes the amount of compartmentalization going on at the facility, which again hints at its importance
It correctly identifies the scientific director, which to an observed eye would narrow it down to something relating to theoretical physics
It reports local accounts of explosive testing on site

If I were a spy thinking about nuclear weapons, I would find that a pretty interesting combination of things, and worth following up on. Of course, it also has a healthy dose of confusion, nonsense, and just plain silliness mixed into it. But even a ray gun that stopped airplanes, or a chemical weapons plant, might be of interest to enemy spies. (Much less Allies who you don’t want snooping around, like the Soviets.) The article has just enough ring of authenticity to it to suggest that something serious was going on at Los Alamos — which makes it much more dangerous than something that was wilder yet potentially closer to the truth.

General Groves — not amused.

The Manhattan Project security apparatus was not amused. Col. Ashbridge, the military head of Los Alamos, sent a copy to Groves a few days after it was published, noting that he had heard that Groves was already aware of it and that it had been shown to Oppenheimer. Ashbridge wrote:¹⁵

We are naturally much perturbed about it and Major [Peer] de Silva [Los Alamos security head] is preparing a memorandum to Lt Col [John] Lansdale [Manhattan Project security head] as to the source of the data collected by the reporter while vacationing in Albuquerque and Santa Fe. There are many rumors around town about this project since thousands of construction workers from this vicinity have been employed at Los Alamos, many of our personnel go into town for shopping and weekends, and Dr. Oppenheimer’s name is fairly well known in Santa Fe.

In discussing this with Major de Silva, he indicated that he felt the “leak” was not something we could have prevented, but that the reporter had doubtless picked up some local gossip, and put it together with information on Dr Oppenheimer in “Who’s Who.”

The late A.J. Connell [director of the Los Alamos Ranch School] informed me several months ago that everyone in Santa Fe knew some sort of scientific project was underway at Los Alamos, but that curiosity had died down when no one found out anything more after several months, and they just accepted us without trying to guess what was done.

The action of the newspaper in printing such an article shows a complete lack of responsibility, compliance with national censorship code and cooperation with the Government in keeping an important project secret. It is hoped that some steps can be taken to deny the paper certain privileges as a result of their disclosure of this project in such an article.

So what did Groves end up doing? First he made sure that it wouldn’t spread further — he put the kibosh on any follow-up stories or further syndication. Time magazine was going to write a follow-up regarding West Coast atom smashing work, but the Office of Censorship stopped them. Then he had the reporter investigated and interviewed. For awhile he thought about getting Raper drafted to the Pacific Theatre — a rather bloodthirsty approach to the problem. He relented on this when, as it turned out, Raper was in his sixties. Not exactly Army grunt material.¹⁶

Did the Axis powers notice this? If they did, they don’t seem to have done much with it. Which highlights an important aspect of Manhattan Project secrecy, in a way: how lucky it was. There were a tremendous number of puzzle pieces out there for an enemy power to notice and put together regarding the bomb effort. It was not quite so perfectly secret as we often talk of it as being. We know it was possible to put some of the pieces together, because the Soviets did it, and even a few others did it. (I’m in the process of writing an article about some of the successful efforts, so more on that later.) Groves wanted a hegemonic, all-encompassing, all-controlling secrecy regime. Understandably, he couldn’t accomplish that — but he pulled off just enough that, with a bit of luck, the project stayed more or less below the water line.

Source: John W. Raper, “Forbidden City,” (13 March 1944) The Cleveland Press. Photostat copy in Manhattan Engineer District records, Records of the Army Corps of Engineers, Record Group 77, National Archives and Records Administration, Box 99, “Investigation Files.” [↩]
While entry to Los Alamos was heavily restricted, many more than “half a dozen” people were allowed to leave. [↩]
This guy is impressively flip, eh? [↩]
The Los Alamos Ranch School. [↩]
Los Alamos is 35 miles northwest of Santa Fe. [↩]
Probably a reference to Col. Whitney Ashbridge, the post commander of the Los Alamos site. Ashbridge had replaced the original military head, Col. John Harman, because the latter had difficulty getting along with the scientists. Ashbridge himself was replaced by Col. Gerard Tyler in late 1944, after Ashbridge’s health began to fail because of the strain brought on by the job. See Vincent C. Jones, Manhattan: The Army and the Atomic Bomb (US Government Printing Office, 1985), 486, 497-498. [↩]
Something of an exaggeration, of course — Oppenheimer’s purely scientific achievements never rivaled Einstein’s. Still, there is some irony in the fact that Oppenheimer would in the postwar take a position as the Director of the Institute for Advanced Study, in the Princeton, New Jersey, and as such effectively become Einstein’s boss. For more on Einstein and Oppenheimer, see S.S. Schweber, Einstein and Oppenheimer: The Meaning of Genius (Harvard University Press, 2010). [↩]
Manhattan Project security speculated that this information came from Oppenheimer’s Who’s Who entry. No comment on whether this “fellow” was a “fellow traveler” or not… [↩]
Again, I don’t really know where he gets this “sealed in” argument from. It is not correct. But it is true that most of the residents were not aware of the final goal of the project. [↩]
This is an exaggeration of the compartmentalization policy, but not so off the mark. Henry Smyth once joked to the New Yorker that because he ran two different divisions in the project, he was not allowed by rules to talk to himself. [↩]
Not entirely off the mark, either in actual purpose or analogy. The first Los Alamos-like installation that I have heard of dates from World War I, the so-called “Mousetrap” factory in Cleveland, where Lewisite (an arsenic-based chemical weapon) was produced. James B. Conant worked on that project. [↩]
Very, very close to the mark. The explosives heard may be related to the implosion studies, which had begun in the summer of 1943. [↩]
The idea of motor-stopping beams is one that pops up in numerous places during speculation about enemy science during World War II. I have even read stories that have said the technology was obvious, though I have no idea what it might have been. [↩]
No, not an electromagnetic pulse. Aside from the fact that no nuclear weapons had been set off by March 1944, the nuclear EMP at ground level is a very short-range effect compared to the blast effects, and if your car was really damaged by an EMP it would not start back up again in 15 minutes. [↩]
Whitney Ashbridge to Leslie R. Groves (18 March 1944), Manhattan Engineer District records, Records of the Army Corps of Engineers, Record Group 77, National Archives and Records Administration, Box 99, “Investigation Files.” [↩]
Patrick S. Washburn, “The Office of Censorship’s Attempt to Control Press Coverage of the Atomic Bomb During World War II,” Journalism Monographs 120 (1990), 1-43, on 11-12, and 37 fn. 43. See also Robert S. Norris, Racing for the Bomb: General Leslie R. Groves, The Manhattan Project’s Indispensable Man (Steerforth Press, 2002), 275-276. [↩]

Tags: 1940s, Espionage, J. Robert Oppenheimer, Leaks, Leslie Groves, Los Alamos, Manhattan Project, Speculation
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What did the Nazis know about the Manhattan Project?

by Alex Wellerstein, published September 13th, 2013

The primary motivation of much Manhattan Project secrecy was to keep the Germans from finding out that the United States and United Kingdom were feverishly working on developing nuclear weapons. So it seems a pretty sensible question to ask: Did it work? That is, did the secrecy keep the Germans from knowing about Allied progress on the bomb?

Strangely enough, I wasn’t able to find much of anything published on the question of what knowledge, if any, the Axis powers had about the atomic bomb. The fact that they didn’t develop one themselves is not strong evidence — it just might mean that such knowledge was very limited, or not believed, or not shared correctly. I can’t do the topic the justice it deserves, because I’m not conversant enough with the sources of Axis foreign intelligence, but I can present some thoughts and intriguing little discoveries on here regarding the German program. If anyone has further thoughts, or evidence, I’m all ears.

Farm Hall, the British country estate.

Where might we look for such evidence? The major, obvious source are the Farm Hall transcripts. Farm Hall was the British country manor where ten of Germany’s nuclear scientists were kept for six months. Their conversations were bugged. They were, on August 7th, told about the atomic bombing of Hiroshima, and the transcripts were carefully probed at the time, and many times since, for any insight given into what the German nuclear weapons program had been at the time. The transcripts are a notoriously tricky primary source, in part because the original German copies have apparently since been lost (so we only have an English translation), and because there are some indications that the scientists were aware they were being bugged. Separately there is the psychological complexity of the issue, as the scientists were trying to come to terms with themselves, an imagined German public, and an imagined world public regarding their participation (or lack thereof) in making nuclear weapons for Hitler.¹

With that said, is there anything in the Farm Hall transcripts that enlightens us one way or the other? The most significant part is that the announcement of Hiroshima, first given orally, “was greeted with incredulity.” See, for example, this sort of exchange:

HEISENBERG: Did they use the word uranium in connection with this atomic bomb?

ALL: No.

HEISENBERG: Then it’s got nothing to do with atoms, but the equivalent of 20,000 tons of high explosive is terrific. […]

GERLACH: Would it be possible that they have got an engine [reactor] running fairly well, that they have had it long enough to separate “93”? [neptunium]

HAHN: I don’t believe it.

HEISENBERG: All I can suggest is that some dilettante in America who knows very little about it has bluffed them in saying: “If you drop this it has the equivalent of 20,000 tons of high explosive” and in reality doesn’t work at all. […]

WEIZSÄCKER: I don’t think it has anything to do with uranium. […]

HAHN: If they really have got it, they have been very clever in keeping it secret.²

All of which has been sometimes taken as pretty strong evidence that these guys didn’t know much about the Allied project. But a closer reading is less clear, because, among other things, not everyone is participating in this discussion. One of the many problems with the German nuclear program was a lack of coordination and a lack of shared knowledge. That Otto Hahn knew nothing of it seems entirely believable, but irrelevant, since he wasn’t really working on the nuclear program in any kind of military capacity. Werner Heisenberg and Carl Friedrich von Weizsäcker worked together so it makes sense that they would be on basically the same page. But what about the others?

Farm Hall mugshots: Werner Heisenberg, Carl Friederich von Weiszäcker, Otto Hahn, and Kurt Diebner.

Walter Gerlach was in a more administrative role, so one might imagine he would know of any foreign intelligence on the subject. He speaks very little in this part of the transcript, only the question about reactors, and he is not one of the outright initial doubters. Asking whether they could have had reactors does not indicate that he was unaware of an Allied bomb project in general, especially given the compartmentalization of the Manhattan Project. He does, much later in the transcript, apparently express private surprise with Heisenberg that “they had known nothing about the preparations that had been made in America,” though. And what of Kurt Diebner? Diebner ran the other major research wing of the German nuclear program, separate from Heisenberg. He says almost nothing in this section of the transcript, only noting that “there is also a photochemical process” for enriching uranium. Again, this tells us nothing about what he knew.³

Probing the transcript further, we find a few other odd exchanges:

HAHN: From the many scientific things which my two American collaborators sent me up to 1940, I could see that the Americans were interested in the business.

WEIZSÄCKER: In 1940 van der Grinten wrote me, saying he was separating isotopes with General Electric.

HARTECK: Was van der Grinten a good man?

WEIZSÄCKER: He wasn’t really very good but the fact that he was being used showed that they were working on it.⁴

I read these as Hahn and Weizsäcker trying to recall whether they had any indication of Allied interest. Considering their only memories are from 1940 (before the Manhattan Project really began), they are actually a good indication that they did not have any truly specific intelligence.

Heisenberg three times tells a story about being contacted from someone in the German Foreign Office about uranium questions:

HEISENBERG: About a year ago, I heard from Segner [probably Sethke] from the Foreign Office that the Americans had threatened to drop a uranium bomb on Dresden if we didn’t surrender soon. At the time I was asked whether I thought it possible, and, with complete conviction, I replied: “No.”⁵

Now that is a strange story. I have no idea what this Sethke would have been referring to — some strange rumor. Whether it is just nonsense, or based on some actual intelligence, it’s impossible to know from just this snippet. Later, when Heisenberg tells another version of the story (this time making his answer that it was “absolutely possible”), he specifies it was in July 1944 and that it was “a senior SS official” who had asked him about the bomb.⁶

More Farm Hall mugshots: Walter Gerlach, Paul Harteck, Max von Laue, Karl Wirtz.

There is also one small exchange before the German scientists were told about Hiroshima. On August 4th, Heisenberg, Gerlach, and Hahn had this exchange:

GERLACH: The [British] Major [Rittner] asked me what we had known about scientific work in enemy countries, especially on uranium. I said, “Absolutely nothing. All the information we got was absurd.”

HEISENBERG: In that respect one should never mention any names even if one knew of a German who had anything to do with it.

GERLACH: For instance, I never mentioned the name of that man Albers (?). The “Secret Service” people kept asking me: “From whom did you get information?” and I always replied: “There was an official in Speer’s ministry and in the Air Ministry who gave it out officially.” I did not say it was Albers (?) who did it.

HEISENBERG: I had a special man who sent me amazing information from Switzerland. That was some special office. Of course I have burnt all the correspondence and I have forgotten his name.

HAHN: Did you actually get any new information from him?

HEISENBERG: At that time I always knew exactly what was being discussed in the Scherrer Institute regarding uranium. Apparently he was often there when Scherrer lectured and knew what they were talking about. It was nothing very exciting but, for instance, he once reported that the Americans had just built a new heavy water plant and that sort of thing.⁷

And there it ends. Other than the mention of heavy water, it is too vague to make much sense of. (The Manhattan Project built several heavy water plants are part of what they called the P-9 Project, as part of their “leave no stone unturned” approach. They upgraded an existing ammonia plant at Trail, British Columbia to produce heavy water, and built three supplementary facilities at military sites in West Virginia, Indiana, and Alabama.)

After the scientists had heard the official BBC radio announcement, they all began to believe it was true, and worked out fairly quickly how it probably would have worked (though even there, they were still impressively confused at times) and famously hashed over why they didn’t get one made. No further invocations of foreign information or intelligence were made that I found.⁸

My overall impression is that for the bulk of the ten scientists, the Allied atomic bomb probably did come as a genuine surprise of immense magnitude. But there are enough hints there to suggest that various bits and pieces were out there amongst their foreign intelligence officials, whether they shared all of that with the scientists or not. And as we’ve see in the Soviet case, just because the spies know something doesn’t mean it percolates back to the scientists working on it — the use of foreign intelligence is not a straightforward operation. And there are several scientists whose reactions were not individually recorded (e.g. Diebner). Of the scientists who talked a lot, they seemed genuinely clueless about what the Americans had done, but not all of them talked.

Are there any other indications? One thing that one finds on the Internet are assertions that the last attempt by the Nazis to deposit saboteurs on American soil, Operation Elster (Magpie), was supposedly aimed at sabotaging the Manhattan Project. Like all such Nazi efforts, the saboteurs in question were rounded up pretty quickly. Were they really targeting the Manhattan Project? I suspect not. The sources that give such information all seem to trace back to a postwar memoir of one of those captured. David Kahn has written that he thinks it is nonsense; I am inclined to agree.⁹) The idea that a single pair of spies would be sent to gain information on, much less sabotage, the Manhattan Project is too silly to be believed without corroborating evidence.

J. Edgar Hoover, 1941. Source.

But there is one last interesting source that I stumbled across. In early February 1945, J. Edgar Hoover wrote a memo to Harry Hopkins (one of Roosevelt’s closest aides) explaining that the FBI had information that indicated German interest in atomic matters. Specifically, Hoover wrote:

As you are well aware, the Army for the past two years has been vitally interested in a highly secret project for the development of an atomic explosive. […]

Recently, in connection with the operation of a radio station by a German agent under control of the Federal Bureau of Investigation but which station the Germans believe to be a free station, an inquiry was received from Germany containing the following questions regarding the status of atomic explosive experimentation in the United States:

First, where is the heavy water being produced? In what quantities? What method? Who are users?

Second, in what Laboratories is work being carried on with large quantities of uranium? Did accidents happen there? What does protection against Neutronic Rays consist of in these laboratories? What is the material and the strength of coating?

Third, is anything known concerning the production of bodies or molecules out of metallic uranium rods, tubes, plates? Are these bodies provided with coverings for protection? Of what do these coverings consist?¹⁰

Now this looks like a legitimate technical intelligence inquiry. These are very specific questions regarding reactor construction. Not necessarily bomb construction, mind you. But it does look like someone working on reactors passed some questions up the chain of command. (The fact, incidentally, that this came to the FBI from a double-agent is also telling — the German foreign intelligence networks were notoriously compromised, yet another reason they missed so much.)

The questions reveal, though, that whomever asked them did not realize that the Americans had already been building massive, industrial-sized, carbon-moderated (not heavy water!) nuclear reactors in Hanford, Washington. Note the lack of any queries regarding uranium enrichment. Note that the questions are narrowly technical, the kind of questions you would ask if you are trying to build your own reactor, not ferret out a clandestine bomb program.

That the Germans were asking such basic, ignorant questions so late in the game — the Red Army was bearing down on Berlin and their atomic program, like so many other things, was in a tizzy¹¹ — is perhaps the greatest indication that they knew very little about the American Manhattan Project indeed. That they were asking questions at all is not surprising, but the lateness perhaps is. The Soviet physicist Georgii Flerov figured out that the Americans must be working on a nuclear program in 1942, when he noticed that nobody was publishing on the subject — specifically, that nobody was citing his publication on the spontaneous fission of uranium-238. One wonders why the Germans were less observant of this fact, especially given the amount of “brain drain” their own institutes suffered.¹² They also appear to have missed or misunderstood all of the various leaks, accidental disclosures, and other signs that drove General Groves and others involved with Manhattan Project security so mad. Many pieces were there for them to put together, but they didn’t solve the puzzle.¹³

Allied troops disassembling the German experimental research reactor at Haigerloch as part of Alsos.

Lastly, we have the take of Samuel Goudsmit, the head of the Alsos expedition. In an unpublished memorandum written in late 1945, claimed that the Alsos investigation into the German work had shown that “the enemy was equally ignorant of Allied scientific and technical work,” though notes that in 1939, a team of three Germans were sent to the USA to learn about American interest in uranium research. (This was well before there was much American interest in such.) As he was prone to do, Goudsmit generalized greatly from this, assuming that scientific and technical intelligence was too difficult to pick up during that war. The Soviets, as always, proved an important exception to Goudsmit’s generalizations.¹⁴ In any case, though, this does indicate that there aren’t probably an exciting espionage gems hiding in the Alsos records.

Wrapping everything up, my basic conclusion is that if German intelligence had an inkling about the American atomic bomb program, they didn’t develop the idea and they didn’t communicate it to several of their top scientists on the program. Heisenberg seems genuinely foolish on the entire subject. Diebner’s lack of participation makes it hard to gauge his knowledge, but it strikes me as strange (though not impossible) that he would know of such things but Heisenberg would be ignorant of them. Entirely separate is the question of who asked the SS to investigate what the Americans were doing with heavy water — but the queries there demonstrate that whomever is asking knows almost nothing about the Allied program, and may in fact be trying to find out how to improve their own reactor work.

A consistent theme in the Farm Hall transcripts and the Alsos investigation is that the Germans seem to have honestly thought that their work on the “uranium problem” was well beyond what anyone else might have been doing, and that the Allies would be desperate to “buy” their reactor research in the postwar. They apparently were not motivated to check to see whether this arrogance was founded, and part of the depression and desperation one sees them going through after Hiroshima and Nagasaki is a remark on their perception of irrelevance. As Otto Hahn chided them right after they learned of Hiroshima: “If the Americans have a uranium bomb then you’re all second raters.”

The best copy of the transcripts is Jeremy Bernstein’s heavily annotated version, Hitler’s Uranium Club: The Secret Recordings at Farm Hall, Second Edition (New York: Copernicus Books, 2001). My quotations and citations refer to this specific version. [↩]
Bernstein, 116-117. [↩]
Photochemical processes for enriching uranium were investigated during the Manhattan Project, but not seriously pursued. [↩]
Bernstein, 119. [↩]
Bernstein, 124. [↩]
Bernstein, 139. [↩]
Bernstein, 108. Note that the (?)’s are in the original transcript. [↩]
There is one small bit about talking about thorium with an (Indian) Japanese spy, but it seems unrelated to the bomb question directly, and the spy in question doesn’t seem to have known anything. [↩]
David Kahn writes in Hitler’s Spies: German Military Intelligence in World War II, “[Erich] Gimpel’s [one of the spies] ghostwritten book, Spy for Germany, must be used with the greatest caution, as it differs in a number of critical points from his statement [to the FBI]. The most important are the book’s claims that he was assigned to ferret out atomic secrets, that he succeeded to some extent, and that he radioed a message to Germany. None of these are supported by his statement or by Colepaugh’s [a collaborator] or by postwar interrogations of his spymasters, and the atomic claim is specifically contradicted by a statement of Schellenberg’s [a top Nazi spy].” There just doesn’t seem to be any hard evidence behind the assertion that Elster had something to do with the Manhattan Project. Gimpel’s books provide zero believable details about the matter — he reports that he was just supposed to figure out what was going on (no list of targets, names, theories, etc. [↩]
J. Edgar Hoover to Harry Hopkins (9 February 1945), in Harrison-Bundy Files Relating to the Development of the Atomic Bomb, 1942-1946, microfilm publication M1108 (Washington, D.C.: National Archives and Records Administration, 1980), Folder 62: “Security (Manhattan Project),” Roll 4, Target 8. [↩]
See Samuel Goudsmit, Alsos (Tomash, 1983 [1946]), 183-185. [↩]
At one point in the Farm Hall transcripts, it is noted that “Hahn remarked on the fact that there had been no publication of work on uranium fission in British or American scientific journals since January 1940, but he thought there had been one published in Russia on the spontaneous fission of uranium with deuterons.” So, at least retrospectively, Hahn realizes that there was this silence, with the exception of Flerov (probably the Russian he is thinking about). [↩]
Goudsmit describes a conversation between Paul Rosbaud and Walther Gerlach in February 1945 in which Rosbaud asks Gerlach, “Have you considered that the American, British, or Russian scientists know as much or perhaps more about it than you do?” If this actually occurred, one wonders if Gerlach didn’t follow up on the issue, ergo the spy query. But this is just supposition. On the conversation, see Goudsmit, Alsos, 185. In any case, the whole conversation, if true, is further evidence of Gerlach’s ignorance at that point — he was still under the delusion that the Allies would have something to gain from the German work on heavy water. [↩]
Samuel Goudsmit to C.P. Nichols, “Scientific Intelligence” (26 November 1945), Goudsmit papers. [↩]

Tags: 1940s, Espionage, FBI, Germany, Hiroshima, Leslie Groves, Manhattan Project, Speculation
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Restricted Data

Heisenberg’s Dresden story: A wartime atomic mystery

Would the atomic bomb have been used against Germany?

The final switch: Goldsboro, 1961

The worst of the Manhattan Project leaks

Forbidden City

What did the Nazis know about the Manhattan Project?

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