Posts Tagged ‘Germany’


Would the atomic bomb have been used against Germany?

Friday, 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.

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.

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.

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.

Loading Fat Man

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.

  1. 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." []
  2. Leslie R. Groves interview with Fred Freed (n.d., ca. 1963), National Archives and Records Administration, RG 200, Box 4, "Groves, Leslie." []
  3. "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. []
  4. And the Gadget was pretty snug inside the Fat Man ballistic casing — I don't see them reducing the diameter. []

What did the Nazis know about the Manhattan Project?

Friday, 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.

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.

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.

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.

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 tizzy11is 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.

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."

  1. 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. []
  2. Bernstein, 116-117. []
  3. Photochemical processes for enriching uranium were investigated during the Manhattan Project, but not seriously pursued. []
  4. Bernstein, 119. []
  5. Bernstein, 124. []
  6. Bernstein, 139. []
  7. Bernstein, 108. Note that the (?)’s are in the original transcript. []
  8. 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. []
  9. 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. []
  10. 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. []
  11. See Samuel Goudsmit, Alsos (Tomash, 1983 [1946]), 183-185. []
  12. 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). []
  13. 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. []
  14. Samuel Goudsmit to C.P. Nichols, "Scientific Intelligence" (26 November 1945), Goudsmit papers. []

Fears of a German dirty bomb

Friday, September 6th, 2013

For good reason, much has been made of the initial fear of a German atomic bomb. But there was another, lesser-known atomic fear as well. If the Germans could make nuclear reactors — which the Americans thought they were probably doing — could they not take the dangerously-radioactive spent-fuel out of them and use them to make dirty bombs? 

Hanford spent fuel rods — the sort of thing that could have been weaponized during World War II as a radiological weapon.

Hanford spent fuel rods — the sort of thing that could have been weaponized during World War II as a radiological weapon.

In the summer of 1942, Arthur Compton, head of the University of Chicago’s Metallurgical Laboratory, wrote a memo to Harvard President and atomic-bomb big-wig James B. Conant expressing the need for “protection against ionizing bombs”:

We have become convinced there is real danger of bombardment by the Germans within the next few months using bombs designed to spread radio-active materials in lethal quantities. ... Since protection against the danger from such bombs will be primarily a matter of detection of radiation and instruction with regards to the dangers, it is essential that the matter be brought at once to the attention of the appropriate military officers.1

Compton and his scientists were, at the time, working under the assumption that the Germans were ahead of the Americans, and had already gotten a nuclear reactor running. They estimated that with a 100 kilowatt reactor, 100,000 Curies of radioactivity could be produced daily for bomb usage.

A radiation survey device of the sort produced during World War II by the Victoreen Instrument Company in Cleveland, in collaboration with the University of Chicago scientists.

A radiation survey device of the sort produced during World War II by the Victoreen Instrument Company in Cleveland, in collaboration with the University of Chicago scientists.

A result of this was that in the fall of 1942, the first steps were taken to, at a minimum, detect whether the Germans used any kind of radiological attack against the Allies. Survey meters were developed that would trigger alarms if they detected high levels of radioactivity. These were secretly dispersed to Manhattan District offices in Boston, Chicago, New York, San Francisco, and Washington, DC. At each location, a small number of officers were trained in their use. Further instruments were held in reserve in case they needed to be deployed further. If the alarms went off,  or if there were other suspicious signs (like reports of a large-scale blackening of photographic film), scientists at the University of Chicago were kept on the ready to be brought in to assess the situation.2

This was a fairly small program, as far as they go. Those involved were acutely aware that the secrecy of the atomic bomb made it impossible to adequately prepare for this possibility. They were stuck in a bind that was very common during the wartime period. The atomic bomb was, at that time, what I like to call an “absolute secret”: the fact that there was a "secret" at all was itself a secret. They could not draw attention to matters relating to atomic energy without drawing attention to the fact that they were engaged in a secret research program with regards to atomic energy. This is a very peculiar situation, one primarily specific to the war, when the secrecy of the project could not be acknowledged (they could not simply say, “oh, the details are secret,” as they could in the Cold War).

What did they think the Germans would do with such a radiological weapon? They considered four possibilities. First, it could be used as an “area-denial” weapon, by making areas uninhabitable. Second, it could be used to contaminate critical war infrastructure (e.g. airports). Third, it could be used as a “radioactive poison gas” to attack troops. Fourth, it could be used “against large cities, to promote panic, and create casualties among civilian populations.”3 Their assessment of the effects, by 1943, was grim:

Areas so contaminated by radioactive material would be dangerous until decay of the material took place, perhaps for weeks or months. ... As a gas warfare instrument the material would be ground into particles of microscopic size to form dust and smoke and distributed by a ground-fired projectile, land vehicles, or aerial bombs.  In this form it would be inhaled by personnel.  The amount necessary to cause death to a person inhaling the material is extremely small.  It has been estimated that one millionth at a gram accumulating in a person's body would be fatal.  There are no known methods of treatment for such a casualty.4

In the time-honored method of worrying about threats, they also then immediately realized that maybe the United States should be weaponizing fission products: “It is the recommendation of this Subcommittee that if military authorities feel that the United States should be ready to use radioactive weapons in case the enemy started it first, studies on the subject should be started immediately.” Note that this isn’t really a deterrent capability, it is a response capability. Deterrence requires your enemy knowing that you have the capability to respond, and secrecy precluded true deterrence.

1943 - Oppenheimer to Fermi

In this context, there is an interesting letter in the J. Robert Oppenheimer papers at the Library of Congress, where Oppenheimer is writing to Enrico Fermi in May 1943 on “the question of radioactively poisoned foods.” From the context, it is clear that both Edward Teller and Fermi had devoted time to this project. The full document is available here. Two parts stand out. One is that one of the acute problems in looking into the issue was, as Oppenheimer put it, difficult to study the subject “without telling anyone about it.” That is, it would be hard to investigate some of the substances in question “without letting a number of people into of the secret of why we want” the substances. The “absolute secret” bind again.

The other is Oppenheimer’s criteria for the project being worth looking into:

...I think that we should not attempt a plan unless we can poison food sufficient to kill a half a million men, since there is no doubt that the actual number affected will, because of non-uniform distribution, be much smaller than this.5

Frank Oppenheimer later called this a very “bloodthirsty” statement by his brother; the historian Barton Bernstein instead argued that this was just scientists trying to help the war effort.6 Either way, it makes Oppenheimer look like a very cold fish indeed. And not much of a “dove.” Even if one isn’t clear how much of a “non-uniform distribution” he was assuming.

1943 - Oppenheimer to Fermi - quote

The offensive angle was basically dropped — they didn’t think they’d need it, and they were focused intently on making the actual atomic bomb, a much more devastating weapon. But defensive measures did proceed. By late 1943, it was thought that the use of radioactive poisons against the UK by the Germans was of low probability, but an unpleasant possibility.7 To avoid being completely taken by surprise in such an event, General Groves (with the concurrence of General Marshall) had four officers from the European Theater of Operations staff briefed on the subject “under most complete secrecy,” and a Manual on Use of Radioactive Materials in Warfare was drawn up for these four officers. Signals officers were instructed to report any “peculiar or unexplained effects” on photographic films or personnel, and the officers in question were given radiation detection instruments to use in the case of suspected cases.

In March 1944, General Groves had the matter brought to the attention of General Dwight D. Eisenhower, commanding general of the Supreme Headquarters Allied Expeditionary Force, fearing that the Nazis might use such weapons to prevent an Allied invasion of Europe. Eisenhower concluded that since the Combined Chiefs of Staff had not brought up the issue, that they must consider that “the enemy will not implement this project.” To keep secrecy, in order to “to avoid a possible scare,” Eisenhower informed only a handful of people, which he acknowledged was not really enough to counter “enemy action of this nature”: “No US or British Commander participating in OVERLORD [the landing at Normandy] has been briefed.” However, radiation detectors were being kept in the UK for deployment on short notice, and a “cover” letter was sent out with symptoms of radiation poisoning listed as a “mild disease of unknown etiology” that was going around, requesting any medical officers to report further cases.8

Dry-run of using radiation detection equipment during a beach landing, as part of "Operation Peppermint." Source.

Team performing a dry-run of a beach landing with radiation detection equipment, as part of "Operation Peppermint." Source.

The plan to deploy radiation monitoring during the D-Day invasions was dubbed “Operation Peppermint,” one of the more amusing code-names of the war. Dry runs of the detection apparatus were taken before D-Day, and German bomb craters were surveyed for radioactive residues, but since no evidence of German radiological weapons preparations or use were uncovered, the “Peppermint” preparations were never put into effect. 

We now know that the Germans never got anywhere near this kind of plan. They didn’t even get a reactor running by the end of the war, the necessary prerequisite for this kind of operation. It wasn’t a totally crazy fear, though. There are aspects of radiological warfare which would make it preferable to, say, chemical warfare from the German point of view. Still, there’s an aspect to this of the old saying, “when the only tool you have is a hammer, every problem looks like a nail.” When you’re studying radioactive hazards intently, every threat looks like a radioactive hazard.

The secrecy angle is what intrigues me the most about this story: the secrecy of the bomb made it difficult to enact serious preparation from this related, but separate threat. The secrecy of one fear made addressing another fear difficult, because the relevant information of both fears were too deeply entangled. 

  1. Arthur H. Compton to James B. Conant (15 July 1942), Bush-Conant file, Roll 7, Target 10, Folder 75, "Espionage." []
  2. Manhattan District History, Book 1, Volume 14, Foreign Intelligence Supplement No. 2 (Peppermint), 31 July 1952. []
  3. "Use of Radioactive Material as a Military Weapon" (n.d., c.a. early 1943). []
  4. Ibid. []
  5. J. Robert Oppenheimer to Enrico Fermi (25 May 1943), J. Robert Oppenheimer Papers, Library of Congress. []
  6. Barton J. Bernstein, "Oppenheimer and the Radioactive Poison Plan," Technology Review, 88 (May-June 1985), 14-17. There is also some follow-up in Barton J. Bernstein, “Four physicists and the bomb: The early years, 1945-1950,” Historical Studies in the Physical and Biological Sciences, 18, No. 2 (1988), pp. 231-263, on 252-253. []
  7. Leslie Groves to George C. Marshall (30 November 1944), Manhattan Engineer District (MED) records, Records of the Army Corps of Engineers, RG 77, National Archives and Records Administration, Box 64, "Security." []
  8. Dwight D. Eisenhower to George Marshall (11 May 1944), Correspondence ("Top Secret") of the Manhattan Engineer District, 1942-1946, microfilm publication M1109 (Washington, D.C.: National Archives and Records Administration, 1980), Roll 5, Target 8, Folder 18, "Radiological Defense." []