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FDR and the bomb

Friday, September 30th, 2016

Franklin D. Roosevelt is one of the most enigmatic figures of the early American atomic bomb program. The four-term US president always features briefly in any story of the Manhattan Project: first, for his creation of the Advisory Committee on Uranium, an exploratory research effort in response to a letter urging government action that was sent by Albert Einstein in August 1939; second, for his approval of a broader expansion of that research into a "pilot" program in late 1941, just before the US entry into World War II, which resulted in more intensive investment into uranium enrichment and reactor design; and third, in mid-1942, Roosevelt approved bringing in the US Army Corps of Engineers to manage a full-scale bomb-production project. This latter action is often subsumed by the attention given the first two, but it is the production program decision that actually resulted in the US getting an atomic bomb by 1945, and is the decision that makes the United States unique among powers in the Second World War, as while several powers had research programs, only the US turned it into a production program. It was the beginning of the Manhattan Project as we tend to characterize it, the kind of program that produces weapons and not just data.

A little history trick I always tell my students: if you see Truman and FDR in the same photograph, that means Truman doesn't know about the atomic bomb. Photo source: History.com

A little history trick I always tell my students: if you see Truman and FDR in the same photograph, that means Truman doesn't know about the atomic bomb. Photo source: History.com

So Roosevelt looms large, as he ought to. Without Roosevelt's actions, there would have been no atomic bomb in World War II. And yet... What did FDR really think about the atomic bomb? Did he see it as a true end-the-war weapon? Did he think it was meant to be used in war (as a first-strike weapon) or did he think of it primarily as a deterrent (i.e., against the Germans)? The question isn't just an idle one, because Roosevelt's sudden death, on April 12, 1945, left his successor, Harry Truman, with major decisions to make about the future of the war, and Truman, in part, thought he was acting in accordance with FDR's wishes on this matter. But, as is well known, FDR never told Truman about the atomic bomb work, and never set out his wishes on this matter — so there was a tremendous amount of assumption involved.

I get asked about FDR's views on a fairly regular basis, and it's one of those wonderful questions that seems simple but is really quite complex, and quickly gets you into what I think of as "epistemological territory": How do we know what someone's views were, in the past? How do we get inside the head of someone dead? Well, you might say, obviously we can't completely get inside someone's head (we can barely get inside the heads of people who are alive and in front of us, and a Freudian might argue that we barely have conscious access to our own motivations and thoughts), but we can look at what evidence there is that was written down that might reveal some of their inner thoughts.

But with FDR, this is very tricky: he didn't write that much down. He didn't keep a diary or journal. He didn't send that many letters. He didn't record phone calls, conversations, write "memos to self," or any of the other documenting habits that are common to major political figures. He was notoriously secretive and private. He didn't explain himself. If Truman was comparatively straightforward in his thinking and action, Roosevelt was a grand schemer, trying to out-wit and out-charm the world (sometimes successfully, sometimes not). He could be downright gnomic. At one point, Vannevar Bush (FDR's top science advisor) asked Roosevelt whether the Secretary of the Navy ought to be included in discussions on the bomb project. He later recalled that FDR "looked at me with one of his strange smiles and said, 'No, I guess not, not now.'" End of anecdote, no real indication as to what FDR was thinking, other than a "strange smile" that no doubt concealed much.1

What approval of a nuclear weapons program looked like under Roosevelt: "VB OK FDR." Report by Vannevar Bush of June 16, 1942, asking to expand the fission work into an all-out effort.

What approval of a nuclear weapons program looked like under Roosevelt: "VB OK FDR." Report by Vannevar Bush of June 16, 1942, asking to expand the fission work into an all-out effort.

As this example indicates, we do sometimes have accounts, including contemporary ones, by people who met with Roosevelt and talked with him. But even these can be quite tricky, because FDR did not, again, generally explain his full thinking. So people like Bush were left with half-versions of the story, knowing what FDR said but not what he thought, and while this is, to be sure, a common-enough human experience, with FDR the gap between thought and expression was exceptionally large.

Separately, there is another, related issue that complicates our understanding: people who met with FDR would often use tales of his agreement as a form of authority. Vannevar Bush did this repeatedly, and this is no doubt a pretty standard mode of operation regarding advisors and presidents. Bush would go to FDR with an idea, convince FDR to sign off on Bush's idea, and then claim it was FDR's idea, because while people might feel free to disagree with Bush, they couldn't really disagree with FDR. One of the most famous examples of this is Bush's report on postwar American science policy, Science—The Endless Frontier, which is constructed to look like it is a reply to a letter by FDR for guidance, but was entirely engineered by Bush as a means of pushing his own agenda, with FDR being a complicit as opposed to a driving force.2

So what do we know? The number of documents that give insight into FDR's personal thoughts about the atomic bomb — what it was, what it could be used for, what his plans were — are very slim. Some of this is a function of timing: FDR died right around when they were getting concrete estimates for when the atomic bomb would be ready to use, and had he lived until, say, May 1945, he might have been faced with more direct questions about his plans for it. (The first Target Committee meeting was on April 27, and the Interim Committee was created in early May, just to give an indication of how things rapidly started to come together right after FDR died.) So he wasn't part of the conversations that directly led to the use of the atomic bombs on Japanese cities.

But there are a few other documents that are useful in assessing FDR's views. It seems fairly clear that FDR's approval of the Uranium Committee in 1939 was initially because he was interested in the deterrent quality of the bomb. Alexander Sachs, who had the meeting with Roosevelt, related that FDR had confirmed that the goal was "to see that the Nazis don't blow us up."3 Again, this wasn't yet a bomb-making program, it was just a "see if bombs are worth worrying about" program, but that's still a little insight: it shows, perhaps, that the initial, explicit attraction was not in making a new wonder-weapon, but deterring against another one.

Roosevelt, Truman, and FDR's previous VP, Henry Wallace. Truman is the only one here who doesn't know about the bomb program. Image source: Truman Library via Wikimedia Commons

Roosevelt, Truman, and FDR's previous VP, Henry Wallace. Truman is the only one here who doesn't know about the bomb program. Image source: Truman Library via Wikimedia Commons

Between 1939 and 1941 there are big gaps in anything that would indicate FDR's views on the bomb. This is not surprising, because this was a period of relative lack of movement in the US fission program, which was not yet a bomb program. FDR was occasionally involved in discussions about the program, but there was no "bomb" yet to worry about one way or the other. In late 1941, FDR approved accelerating and expanding the research, at the urging of Bush, James Conant, Ernest Lawrence, and Arthur Compton, and in mid-1942 he approved of a full bomb production program, as previously noted. None of these documents indicate intent for use, however. The June 1942 report by Vannevar Bush and James Conant, whose approval by Roosevelt is indicated only by a scrawled "VB OK FDR" on its cover letter, indicates that a weapon made with 5-10 kilograms of U-235 or Pu-239 (then just called "Element 94") would have an explosive power of "several thousand tons of TNT." It goes into great detail on the types of plants to be constructed and the organization of the research. It predicts a "bomb" would be ready by early 1944. But at no point does it indicate what the point of such a weapon was: as a deterrent, as a first-strike weapon, as a demonstration device, etc. There is only point, towards the end, which suggests that a committee be eventually formed to consider "the military uses of the material," but even this is primarily concerned with research and development for the plants. This is not to say that Bush, Conant, et al. did not have their views on whether it would be a weapon to use or not — but the report does not indicate any such views, and so FDR's endorsement of it doesn't tell us much.4

Bush met with Roosevelt many times during the war, and sometimes would write down, afterwards, what they talked about. Clearly this is FDR-as-filtered-through-Bush, but we'll take what we can get. In late June 1943, Bush wrote to Conant with an account of a recent meeting he had with FDR on "S-1," their code for the bomb work. In it, Bush related that FDR was curious about the progress of the work and the schedule for having a bomb. Bush told him things were going well but still tentative, and that the date of a bomb had been pushed back to early January 1945, but that this could shift in either direction. FDR also wanted to know how the Germans were doing. Bush explained that they didn't really know, that they were trying to find ways to slow down any German work, and that they were still worried about being behind the Germans. (They would eventually come to understand they had surpassed them.) Then there is this really interesting passage which is worth quoting from the original:

He [FDR] then himself discussed what the enemy attitude of mind would be if they felt they had this coming along, and were inclined to remain on the defensive until it could eventuate. We then spoke briefly of the possible use against Japan, or the Japanese fleet, and I brought out, or I tried to, that because at this point I do not think I was really successful in getting the idea across, that our point of view or our emphasis on the program would shift if we had in mind use against Japan as compared with use against Germany.5

After which the conversation then shifted to other matters. Such a tantalizing snippet of discussion, but not as fleshed out as one might want! What did Bush and FDR understand the difference to be between the Japanese versus the Germans? Who initially brought up the possibility of use against the Japanese? What did FDR think about the German "attitude of mind"? This snippet hints at exactly the topics one might care about but doesn't actually reveal anything about FDR's views on them! Impressively frustrating!

Most of FDR's interactions with Bush, Groves, and others during this period concerned diplomatic issues, specifically cooperation with the British (a rather long, drawn-out saga), and even a meeting with Niels Bohr (from which FDR mostly took away a fear that Bohr might alert the Soviets, or others, to the US work). FDR helped, for example, in helping to shut down unionization activities at the Berkeley Radiation Laboratory, and was kept abreast of efforts made to monopolize global uranium ore resources. He was not "checked out" in any respect; he was dramatically more concerned with the ins-and-outs of the fission work than, say, Truman would later be. But again, very little of this left any record about what he thought they were going to do with the bomb.6

Atomic diplomacy: Roosevelt and Churchill at Quebec, in September 1944. Source: NARA via Wikimedia Commons

Atomic diplomacy: Roosevelt and Churchill at Quebec, in September 1944. Source: NARA via Wikimedia Commons

Two of the only documents that reveal any FDR-specific thoughts about the use of the bomb were agreements he made with Winston Churchill. In August 1943, Churchill and Roosevelt met in Quebec, Canada, and hammered out the secret "Quebec Agreement." It said, among other matters, that the US and UK would pool their efforts at both making the bomb and securing global uranium reserves, that they would never nuke each other, that they would never nuke anyone else without mutual agreement, and they would not reveal the secrets of the bombs without mutual agreement. So this at least provides a framework for using the bomb, but it is a limited one — FDR was willing to deliberately tie the US's hands with regards to dropping of the atomic bomb to the approval of a foreign power, quite an amazing concession!7

Another meeting between Roosevelt and Churchill, in Hyde Park, New York, produced yet another fascinating agreement. The Hyde Park Aide-Mémoire of September 1944 contained the following clause:

The suggestion that the world should be informed regarding tube alloys, with a view to an international agreement regarding its control and use, is not accepted. The matter should continue to be regarded as of the utmost secrecy; but when a “bomb” is finally available, it might perhaps, after mature consideration, be used against the Japanese, who should be warned that this bombardment will be repeated until they surrender.

Here they were explicitly rejecting the appeal by Niels Bohr (which he was able to make personally to both FDR and Churchill, on separate occasions) to alert the world about the atomic bomb. But it is of interest that they were, at this point, specifically thinking about using the bomb against the Japanese (not Germany), but that they thought it would require "mature consideration" before use, and that they were putting "bomb" in scare-quotes. This is one of the few indications we have of FDR's awareness and acceptance of the idea that the bomb might be used as a first-strike weapon, and against the Japanese in particular.

Lastly, there is one other significant FDR-specific datapoint, which I have written about at length before. In late December 1944, with Yalta looming, Roosevelt and Groves met in the Oval Office (along with Henry Stimson, the Secretary of War). In Groves' much later recollection (so we can make of that what we will), Roosevelt asked if the atomic bomb might be ready to use against Germany very soon. Groves explained that for a variety of reasons, the most important one being that their schedule had pushed the bomb back to the summer of 1945, this would not be possible. It is an interesting piece, one that simultaneously reveals Roosevelt's potential willingness to use the atomic bomb as a first-strike weapon, his willingness to use it against Germany specifically, and the fact that FDR was sufficiently out of the loop on planning discussions to not know that this would both be impossible and very difficult. In other words, it reveals that FDR wasn't aware that by that point, it was expected that the bomb could only be used against Japan, and that is a rather large thing for him not to know — further evidence, perhaps, that he was not completely abreast of these kinds of discussions. At the meeting, Groves gave FDR a report that predicted a weapon ready for use in early August 1945, and specified that it was time to begin military planning, which Groves annotated as having been "approved" by the Secretary of War and the President. But there doesn't seem to have been any specifics of targets, or even targeting philosophy, agreed upon at this point.8

What can we make of all this? Frequently I have seen people take the position that Truman himself took: assuming that Roosevelt would have used the bomb in the way that Truman did, because what else might he have been planning? I would only caution that there were more "options" on the table even for Truman than we tend to talk about, which is just another way to say that dropping two atomic bombs in rapid succession on cities is not the only way to use an atomic bomb even militarily. That is, even if one thinks it was inevitable that the bombs would be used in a military fashion (which I think is probably true), it is unclear what position FDR might have taken on the question of specific targets (e.g., the Kyoto question), the question of timing (e.g., before or after the Soviet invasion; how many days between each strike?), and diplomatic matters (e.g., would Roosevelt be more open to modifying the Potsdam Declaration terms than Truman was?). So there is room for considerable variability in the "what if Roosevelt hadn't died when he did?" question, especially given that Roosevelt, unlike Truman, had been following the bomb work from the start, and was as a result much less reliant on his advisors' views than Truman was (he frequently bucked Bush, for example, when it came to matters relating to the British).

Would Roosevelt have dropped the bomb on Japan, had he not died? I suspect the answer is yes. One can see, in these brief data points, a mind warming up to the idea of the atomic bomb as not just a deterrent, but a weapon, one that might be deployed as a first-strike attack. In some ways, FDR's query to Groves about Germany is the most interesting piece: this was a step further than anyone else at the time was really making, since Germany's defeat seemed inevitable at that point. But, again, the strict answer is, of course, that we can't really know for sure. Perhaps if FDR had confided his inner thoughts on the bomb to more people, perhaps if he had written them down, perhaps if he had been more involved in the early targeting questions, then we would be able to say something with more confidence. Unless some new source emerges, I suspect Roosevelt's thoughts on the bomb will always have something of an enigma to them. It is not too far-fetched to suggest that this may have always been his intention.

Notes
  1. Vannevar Bush, Pieces of the action (New York: Morrow, 1970), 134. []
  2. See Daniel J. Kevles, "The National Science Foundation and the Debate over Postwar Research Policy, 1942-1945: A Political Interpretation of Science–The Endless Frontier," Isis 68, no. 1 (1977), 4-26. Another example of this behavior, from my own research, is when Bush wanted to seize patent rights relating to atomic research during the war — this was an idea cooked up by Bush, approved by FDR, and then presented as an idea of FDR's, to give it more political, legal, and moral heft. See Alex Wellerstein, "Patenting the Bomb: Nuclear Weapons, Intellectual Property, and Technological Control," Isis 99, no. 1 (2008), 57-87, esp. 65-66. []
  3. Quoted in Richard Rhodes, The Making of the Atomic Bomb (Simon and Schuster, 1986), on 314. []
  4. Vannevar Bush and James Conant, "Atomic Fission Bombs," (17 June 1942), with attached cover letter initialed by Roosevelt, copy 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 58: "Vannevar Bush Report - March 1942," Roll 4, Target 4. []
  5. Vannevar Bush to James Conant, "Memorandum of Conference with the President," (24 June 1943), copy in Bush-Conant File Relating the Development of the Atomic Bomb, 1940-1945, Records of the Office of Scientific Research and Development, RG 227, microfilm publication M1392, National Archives and Records Administration, Washington, D.C., n.d. (ca. 1990), Roll 2, Target 5, Folder 10, "S-1 British Relations Prior to the Interim Committee [Fldr.] No. 2 [1943, some 1944, 1945]." []
  6. For a very nice discussion of Roosevelt's wartime "atomic diplomacy," see Campbell Craig and Sergey Radchenko, The atomic bomb and the origins of the Cold War (Yale University Press, 2008), chapter 1, "Franklin Delano Roosevelt and Atomic Wartime Diplomacy," 1-33. On the UK-US atomic alliances, see Barton Bernstein, “The uneasy alliance: Roosevelt, Churchill, and the atomic bomb, 1940-1945,” Western Political Quarterly 29, no. 2 (1976), 202-230 []
  7. And just to follow up on that: the US did, in the summer of 1945, request formal UK approval for the dropping of the atomic bomb, and for the release of the Smyth Report and other publicity. The UK readily gave assent to using the weapon against the Japanese, but they did question the wisdom of releasing the Smyth Report. They eventually consented to that as well, after stating their reservations. []
  8. Just as an aside: the meeting, by Stimson's diary account, was only 15 minutes long, and most of it pertained to questions of diplomacy (specifically potential British violations of the Quebec Agreement with respect to French patent arrangements). Stimson's diary entry mentions nothing about targeting question, German, Japanese, or otherwise. So either the discussion of Germany and Japan did not make much impression on him, or he did not think it prudent to write it down. See Henry Stimson diary entry for December 30, 1944, Yale University. Groves own contemporary record of the meeting also neglects to mention anything relating to targets, and instead is entirely focused on diplomatic questions. Leslie Groves, Memorandum on Meeting with President (30 December 1944), 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 7, Folder 24, "Memorandums to (Gen.) L. R. Groves Covering Two Meetings with the President (Dec. 30, 1944, and Apr. 25, 1945)." []
Meditations

The luck of Kokura

Friday, August 22nd, 2014

On the morning of August 9th, 1945, a B-29 bomber left the island of Tinian intending to drop an atomic bomb on the city of Kokura, the location of one of the largest arsenals still standing in Japan. On arriving at the target, the plane found it obscured by clouds. It turned south and went to its secondary target: Nagasaki. 

Supposedly, some in Japan still refer to the "luck of Kokura" in reference to this time in which some bad weather saved the lives of tens of thousands of people there. But what really happened that morning? Was it bad weather, or something else, that obscured, and thus saved, Kokura? 

Surprisingly, there are actually a few different theories floating around, and the uncertainty over the matter is generally not realized or acknowledged.

Model of the Kokura arsenal made for targeting purposes, ca. 1945. North is in the lower-right hand corner. Source: USAAF photos, via Fold3.com.

Model of the Kokura arsenal made for targeting purposes, ca. 1945. North is in the lower-right hand corner. Source: USAAF photos, via Fold3.com.

But first, let's review the basics of the mission. The Kokura/Nagasaki mission (dubbed CENTERBOARD II), as with the Hiroshima mission before it (CENTERBOARD I), did not involve the bomber flying on its lonesome to the target, as is sometimes imagined. There were a total of six planes involved in the mission, all B-29 bombers. One of them was the strike plane that carried the Fat Man implosion bomb (Bockscar).1  Two other planes (The Great Artiste and Big Stink) were instrument and observation planes. One other plane was a "standby" plane (Full House) that was to serve as backup if the three bombing planes ran into air resistance — because they didn't, it instead flew back to Iwo Jima instead of on to the target after a rendezvous with the bombing plane. Lastly, there were two weather planes that flew out in advance, one to Nagasaki (the Laggin' Dragon), the other to Kokura (the Enola Gay, the same plane that had dropped the atomic bomb on Hiroshima a few days earlier, but with a different crew). The weather planes would check out bombing conditions and then circle back, helping the bomber plane determine whether the primary or secondary target would be used. Niigata, a third atomic bombing target, was not considered on this mission because of its great geographical distance from Kokura and Nagasaki.

Bockscar was being piloted by Major Charles Sweeney. It had taken off from the island of Tinian at 3:47am, Tinian time. They had arrived at a rendezvous point at Yakushima Island around 9:15am. It rendezvoused with one of the other B-29s (the instrument plane), but did not spot the other one (the photo plane). At 9:50am, the pilot of Bockscar, Charles Sweeney, gave up and continued on to Kokura, having waited some 30 minutes longer than he was supposed to. At 10:44am, they arrived at Kokura. The flight log records that "Target was obscured by heavy ground haze and smoke." A crew member of Bockscar rated it as "7/10 clouds coverage – Bomb must be dropped visually but I don't think our chances are very good."2

Three bombing runs on Kokura were attempted, but "at no time was the aiming point seen," as the flight log recorded. Visual bombing had been made a mandatory requirement (they did not trust the accuracy of radar-assisted bombing), so this made Kokura a failed mission. Since Bockscar had limited fuel, Sweeney decided to continue on to the secondary target, Nagasaki. They arrived at Nagasaki at 11:50am, which they also found obscured by smoke and clouds, to the degree that they made the target approach entirely by radar. Right at the last possible moment, the clouds parted just enough for the bombardier to site the target and drop the bomb. (It missed the intended target by a significant margin.) Bockscar circled the target once and then, at 12:05pm, took off for Okinawa, and from there, after refueling, Tinian.

Care about the details of the Hiroshima and Nagasaki bombings? Get this book.

Care about the details of the Hiroshima and Nagasaki bombings? Get John's book. I'm not just saying that because he says nice things about my blog, either.

An aside: For anyone interested in the nitty-gritty details of the Hiroshima and Nagasaki missions, my go-to reference these days is John Coster-Mullen's Atom Bombs: The Top Secret Insider Story of Little Boy and Fat Man. I first got a copy of John's book in 2006 or so. John sent me a new copy a few months ago, and I have been impressed with how much new material he has added over the last 8 years. (And I have managed to find a few useful things for him over the years, which have made it into his book as well — duly credited!) If you're interested in the history of the Manhattan Project, you can't not have a copy of John's book... and if your copy is over 5 years old, considered getting an updated edition! All of these little details about times and planes and whatnot come from John's book.

So what caused the "heavy ground haze and smoke"?

Theory #1: Bad weather

The most common explanation for the obscuring of Kokura is one of weather. It seems to me to be a valid possibility, but let's pick it apart a bit.

As noted, the Enola Gay had flown ahead to Kokura to scope out the visual conditions. They had radioed back that the visibility was "3/10 low clouds, no intermediate or high clouds, and forecast of improving conditions."3 That was a favorable-enough weather report that Kokura, the primary target, was chosen as the first run. Upon arriving, however, Bockscar found the weather conditions were now 7/10 — too obscured to bomb. Is this plausible?

Summer weather patterns in Japan, map made in early 1945. Not great for bombing. Source: Produced for the USAAF's IMPACT magazine, high-res version via Fold3.com.

Summer weather patterns in Japan, map made in early 1945. Not great for bombing. Source: Produced for the USAAF's IMPACT magazine, high-res version via Fold3.com. There is another wonderful map for winter weather as well.

General Groves, in his 1964 memoir, suggests that it might have been the case that the change in weather conditions was simply a matter of how much time had passed between the forecast and arrival of Bockscar. The strike plane was, as noted, delayed by around half an hour. Groves also implies that there may have been a difference between how visual the target was at an angle — how a bombardier sees it — and how it looks from straight above — how a weather plane sees it). He concludes that the reasons for the haze were "never determined."4

On the face of it, it's hard to know whether such a rapid change in visibility is possible through entirely natural causes. In some parts of the world, the weather can be very volatile. Japan is one of these parts of the world, especially around the late fall. The variability of Japanese weather conditions was something that the US Army Air Forces knew very well, and was one of the bane of their bombing plans. It was a major issue in the atomic bombing discussions as well since very early on. At the first Target Committee meeting in April 1945, weather was a major point of discussion:

...it was pointed out that the months in which the initial mission will be run constitute the worst weather months of Japan. [...] Dennison pointed out that all weather maps indicated that there were only an average of 6 good bombing days in August and that of those 6 days a conservative estimate would probably result in safely predicting that we would have 3 good days in the month of August but these 3 good days could not be positively predicted in advance of more than 48 hours. 

Elsewhere in the memo it remarks that "3/10ths or less" cloud coverage was considered acceptable for visual bombing. It also notes that "only once in 6 years have there ever been 2 successive good visual bombing days of Tokyo," which gives some indication of the weather's variability.

Weather from the nearby city of Shimonoseki for August 8-9, 1945. Click to enlarge, or click here for the Excel file. Source: Japanese M

Weather from the nearby city of Shimonoseki for August 8-9, 1945. Click to enlarge, or click here for the Excel file. Source: Courtesy of the Japanese Meteorological Agency.

So it doesn't seem impossible that it could have just been according to the weather, though the big difference between the conditions reported by the weather plane and the observed conditions by the strike plane seem, on the face of it, beyond what a half hour's delay would accomplish. One question I don't have the answer for is when the weather plane radioed those conditions back. In the case of the Hiroshima run, the weather plane was only 30 minutes earlier than the strike plane. If we assume that was a similar attempt on the second mission, it would mean that the strike plane was reaching the target over an hour after the weather plane had seen it, which could be a significant-enough delay for a serious change in visibility. (And another possibility is that the weather plane could have been, for whatever reason, incorrect — either at the wrong place or had its message garbled.)

There aren't good weather records from this period, at least none I have seen. The closest site for state weather recording was in Shimonoseki, some 7 miles / 11 km northeast of Kokura. I asked the Japan Meteorological Agency for any records they had from that period and they sent me the above data.5 It is not especially helpful towards answering this question that I can see, but I'm not a meteorologist in the slightest. For me, the big take-away from the data is that it could go from totally clear to totally obscured over the course of an hour, which at least supports the plausibility of the weather theory.

Theory #2: Smoke from firebombing

One of the other causes put forward is that the "smoke and haze" seen over Kokura was actually a result of nearby firebombing. On August 8th, 1945, the 20th AF had sent 221 B-29s to the nearby city of Yahata (Yawata) to drop incendiary bombs.6 Yahata had been bombed several times during the war. It was, in fact, the site of the first B-29 attack on the Japanese homeland in June 1944, and indeed the first bombing attack against the Japanese homeland at all since the Doolittle raid. It had been bombed again in August 1944. The USAAF considered Yahata to be the largest steel producing center in the country, and dubbed it "the Pittsburgh of Japan." It was the last Japanese city to be hit by a massive B-29 raid, a "night burn job" as a USAAF writer put it, and it was considered "leftover business" that had been scheduled to take place much earlier but delayed because of bad weather.7

Yahata/Yawata target map, March 1945. Kokura arsenal is visible to the east. Source: JapanAirRaids.org. Click here for the uncropped, unadjusted version.

Yahata/Yawata target map, March 1945. Kokura arsenal is visible to the east. Source: JapanAirRaids.org. Click here for the uncropped, unadjusted version.

The weather at Yahata had been 4/10 clouds over the target, but this didn't matter for B-29 firebombing raids, because accuracy was not as big a concern as with the atomic bombs. The planes had arrived at Yahata around noontime. I've found very little in terms of documentation about how much of Yahata was burned out with this raid — perhaps because it was so late in the war, many of the traditional sources for information about incendiary bombing results (especially those contained on the invaluable website JapanAirRaids.org) essentially omit any discussion of this final big raid.

Could the bombing of Yahata have been the cause of the smoke that obscured Kokura? It doesn't seem impossible, but it seems to me to be somewhat unlikely.

Approximate areas of interest in Yahata and Kokura, as seen on Google Earth today.

Approximate areas of interest in Yahata and Kokura, as seen on Google Earth today.

Bockscar was flying over Kokura just a little under 24 hours after the Yahata raid began. Incendiary raids did produce extreme amounts of smoke cover, as other photographic evidence indicates clearly. Yahata was only around 6 miles / 9 km west of Kokura (and their proximity is emphasized by the fact that both are today just considered wards of a larger city, Kitakyushu).

It seems odd that the Yahata smoke would have caught them off-guard. Wouldn't the weather plane have noticed that there was smoke over Yahata rolling towards Kokura, or at least threatening it? Yahata is close enough that at the 30,000 feet or so that a weather plane would be flying over Kokura, all they would have to do is glance in its direction to see if there was heavy cloud cover. (One can easily replicate this experience with Google Earth if one chooses.) Could the smoke cloud have been lagged behind by just the amount of time that the weather plane wouldn't see it, then rush ahead to obscure Kokura an hour later? Could the smoke have gone from non-obscuring to obscuring in just an hour? At the wind speeds measured at Shimonoseki (around 2-12 mph), it doesn't strike me as super likely, but I'm not an expert in this kind of thing.

Theory #3: Japanese smokescreen

One last, more obscure theory. I first read of this in John Coster-Mullen's book. I will quote him here:

When [Bockscar] finally arrived at 10:44 AM, smoke and industrial haze had obscured Kokura. Yahata had been firebombed by over 200 of LeMay's B-29's the previous day and the smoke had drifted over nearby Kokura. There was also a POW camp right next door to the main downtown power plan. An American prisoner in this camp reported later the Japanese had installed a large pipe that went from the power plant down to the river. He stated that whenever B-29's were sighted over Kokura, the steam in the plant was diverted through this pipe and into the river. This created enormous condensation clouds that also helped to obscure the city.

John himself seems to have interviewed the POW camp survivor in question, and notes in a footnote that he thinks this was the first time this claim had surfaced in print. I certainly hadn't seen it anywhere prior to John's book. John asked Commander Ashworth about this in 1995, and Ashworth replied that this seemed possible, and added "if the Japanese really did that, then they were damn clever!"

German smokescreen use at Wilhelmshaven in June 1943. Caption: "Despite a smoke screen, 168 B-17s of the Eighth Air Force attacked Wilhelmshaven on 11 June. There are three lines of generators to windward of the area covered when the wind is in the north, as it was in this case. Generator boats are at the upper left. Despite the extent of the smoke screen hits are observed inside the circle..." Source: USAAAF IMPACT magazine, vol. 1, No. 5, August 1945, page 18.

German smokescreen use at Wilhelmshaven in June 1943. Caption: "Despite a smoke screen, 168 B-17s of the Eighth Air Force attacked Wilhelmshaven on 11 June. There are three lines of generators to windward of the area covered when the wind is in the north, as it was in this case. Generator boats are at the upper left. Despite the extent of the smoke screen hits are observed inside the circle..." Source: USAAAF IMPACT magazine, vol. 1, No. 5, August 1943, page 18.

A few weeks ago, there was a story carried by Japanese newspapers along these lines:

As the 69th anniversary of the Nagasaki atomic bombing approaches, a former mill worker in the present-day city of Kitakyushu, Fukuoka Prefecture, spoke about his untold story on how he burned coal tar to block the view of U.S. aircraft as they were about to drop the A-bomb on the city. ... Of the three workers, Oita resident Satoru Miyashiro, 85, who worked at a can factory in the steel mill at around the end of the war said he burned coal tar to lay a smoke screen on Aug. 9, 1945. ... Miyashiro said about two days before the Nagasaki attack Yawata steel workers learned that Hiroshima had been wiped out by the "new bomb" from their colleagues who had come back to Yawata via Hiroshima. He thought the next target would be his city as there were arms factories located in the area.

Note that this isn't quite the same thing — this is someone in Yahata who was burning coal tar after hearing an air raid drill, and the smoke going downwind (east) to Kokura. I find it a little odd that the worker in question doesn't mention that Yahata itself was firebombed less than a day before he decided to do this.

Are either of these theories plausible? In terms of, could they have done these things — of course. Turning on an incinerator is not an implausible action, and neither is the steam cloud scenario.

But would this have reduced the visibility over Kokura from 3/10 to 7/10 in the time it took the strike plane to get there? I'm not an atmospheric scientist, so I wouldn't want to hazard a strong position on this. One can presumably model both of these scenarios and see if either were possible. I would be extremely interested if anyone wanted to that!

Susquehanna Steam Electric Station — just an example of what a very large nuclear power plant can generate in terms of steam. It's a lot of steam. Could it obscure a city downwind of it from a B-29 bomber? Image source.

Susquehanna Steam Electric Station — just an example of what a very large nuclear power plant can generate in terms of steam. It's a lot of steam. Could it obscure a city downwind of it from a B-29 bomber? Image source.

My gut thought is that they were not super likely to be wholly responsible for the cloud cover. If it had been steam from a single plant, I suspect someone on Bockscar would have noted it as such. We have lots of experience with steam-generating power plants — think of the clouds created by nuclear cooling towers. They certainly can put out a lot of steam. Would it be enough to block off the entire city? I'm kind of dubious.

What about the coal tar possibility? I'm especially dubious that this would have been enough. Setting up honest-to-god smokescreen for an entire city is hard work, even if you are a professional. When the Germans wanted to protect individual places (like plants) from bombers they set up dozens to hundreds of smoke pots to do the job, or used multiple dedicated smoke generators. Some of the larger smokescreen images I have found clearly involve lots of smoke sources placed at good intervals upwind of the target they are meant to protect. So I don't know.

On the other hand, if the smoke from Yahata was not from the firebombing but instead something deliberate, it would explain the time delay issue. If the wind was going due east at around 5 mph, that would in fact be perfect for putting a smoke cover over Kokura. So it has its merits as a theory.

Conclusion

There are narrative aspects of each theory that appeal, and each of them change what is meant by the "luck of Kokura." If bad weather is what saved Kokura, then it becomes a metaphor for how serendipitously life and death are dealt out by the hands of fate. If it was smoke from the firebombing of Yahata, then it becomes an ironic story about the Army Air Forces' zeal for destruction could become counterproductive. If it was the result of deliberate action on behalf of the Japanese, then it becomes something much more complicated, a story about how individual action may have led to the saving of some lives... and the dooming of others. It also would change the standard story of how defenseless the Japanese were against these weapons.

The bombing of Nagasaki. Original source. Slightly edited to improve foreground/background distinction.

Of course, what was lucky for Kokura was not so for Nagasaki.

Looking at these three options, I find the weather theory the easiest one to stomach. Japanese weather patterns were notoriously hard to predict and it was known as the worst season for bombing conditions. That they could change over an hour seems unsurprising to me, especially for a coastal city, where clouds can come and go which impressive rapidity (as someone who has lived in the Berkeley, Boston, and New York areas can attest). I like the irony of the Yahata story, but there are things that just don't add up — I don't see why the weather plane would not have mentioned it, and it seems implausible to me that it would take almost exactly 24 hours for the heavy cloud cover to have migrated a mere 5-10 miles. And for reasons indicated, I'm not sure I buy the smokescreen story — it would have been really difficult to pull off that degree of cloud cover reliably. It would have taken tremendous foresight and luck. And it is strange that this story would be "buried" for so long. This doesn't mean that someone didn't try it (I am emphatically not calling anyone a liar!). It just means that I'm not sure it would have worked even if they did try it.

A separate possibility is "all of the above." Maybe the weather was bad. Maybe there was haze from the Yahata bombing. Maybe someone did try to release steam or smokescreen. Maybe all of these things occurred at once, making "the luck of Kokura" something that was the result of multiple causes. That would make Kokura extra lucky, I suppose, and not fit into any of the above pat narratives. And make Nagasaki extra un-lucky in turn.

In the end, it doesn't really matter which of these things happened. The bare fact is that Kokura didn't get bombed and Nagasaki did. But I find looking into these kinds of questions useful as a historian. Too often it is easy to take for granted that the explanations given in narrative works of history are "settled," when really they are often resting on very thin evidence, thinner perhaps than the historian who writes them realizes. I don't think we really know what happened at Kokura, and I'm not sure we ever truly will.

Notes
  1. Sometimes you see it as "Bock's Car," but it said "Bockscar" on the side of the B-29. This is one of those places where I say, "who cares?" but purists are concerned with this kind of detail. []
  2. Flight diary of Lt. Fred Olivi, quoted in Coster-Mullen's book. []
  3. Bockscar flight log by Commander Frederick Ashworth, included in Norman F. Ramsey, "History of Project A," (27 September 1945). A full of copy of Ramsey's report is included in Coster-Mullen's Atom Bombs book. []
  4. Leslie Groves, Now it Can Be Told, 345: "At Kokura, they found that visual bombing was not possible, although the weather plane had reported that it should be. Whether this unexpected condition was due to the time lag, or to the difference between an observer looking straight down and a bombardier looking at the target on a slant, was never determined." []
  5. Here is the original Excel file they sent me. []
  6. Most US sources list the city as "Yawata," but it apparently corresponds with what is today transliterated as the city of Yahata, in Fukoka prefecture, and there is an entirely different city known as Yawata in Kyoto Prefecture. The kanji is the same. Yahata has since been absorbed by Kitakyushu, along with Kokura. []
  7. Tom Prideaux, "Mission to Yawata, 7 Aug. 1945," IMPACT, vol. 3, no. 9 (September-October 1945), 53. []
Visions

Firebombs, U.S.A.

Wednesday, March 12th, 2014

After the atomic bombs were dropped on Japanese cities, it didn't take long for the US public, to start drawing what it would look like if atomic bombs went off over their own cities. PM, a New York City newspaper, may have inaugurated the genre with its August 7, 1945, issue, when it took what scant facts were known about Hiroshima and superimposed the data onto the Manhattan skyline:

PM - NYC atomic bomb - August 1945

This impulse — to see what the bomb did to others, and then to apply it to one's own cities — worked on at least two levels. In once sense it was about making sense of the damage in intuitive terms, because maps of Hiroshima don't make a lot of intuitive sense unless you know Hiroshima, the city. Which very few Americans would.

But it's also a recognition that atomic bombs could possibly be dropped on the USA in the future. The atomic bomb was immediately seen as a weapon of the next war as well as the present one. It was a weapon that would, eventually, make the United States very vulnerable.

Considering how many non-atomic bombs the US dropped on Japan during the war, it's a little interesting that nobody has spent very much time worrying about what would happen if someone firebombed the United States. Why not? Because the U.S. has never imagined that any other nation would have the kind of air superiority to pull off sustained operations like that. No, if someone was going to bomb us, it would be a one-time, brief affair.

When the US did invoke American comparisons for firebombing, it was to give a sense of scale. So the Arnold report in 1945 included this evocative diagram of Japanese cities bombed, with American cities added to give a sense of relative size:

Arnold map - Japan firebombing

So I was kind of interested to find that in the final, late-1945 issue of IMPACT, a US Army Air Forces magazine, contained a really quite remarkable map. They took the same data of the above map — the Japanese cities and their equivalent US cities — and projected them not on Japan, but on the continental United States.

It's the only attempt I've seen to make a visualization that showed the damage of the ruinous American air campaign against Japan in such a vivid way:1

Click to enlarge.

Click to enlarge.

The correspondences between US and Japanese cities were chosen based on the US Census of 1940 and presumably a Japanese census from around the same period. The above map isn't, the text emphasizes, a realistic attack scenario. Rather, it is meant to show this:

If the 69 U.S. cities on the map at right had been mattered by Jap bombers free to strike any time and anywhere in this country, you can vividly imagine the frightful impact it would have had upon our morale and war potential. Yet this is precisely what the B-29s did to Japan.

What's remarkable is that this isn't some kind of anti-bombing screed; it's pro-bombing propaganda. Both of these images are bragging. The text goes on to emphasize that if someone were really targeting the US, they'd hit industrial centers like Detroit, Philadelphia, and Pittsburgh — to say nothing of Washington, DC, which is conspicuously absent and unmentioned.

IMPACT was classified "confidential" during the war, meaning it had a circulation of about 10,000 airmen. It's a pretty wonderful read in general — it's a vociferously pro-Air Forces rag, and is all about the importance of strategic bombing. As one might expect, it de-emphasizes the atomic bombings, in part to push back against the very public perception that we have today, where the last two major bombings are emphasized and the other 67 are forgotten. On the above maps, Hiroshima and Nagasaki are unremarkable, easily in the crowd.

I thought it would be interesting to copy out all of the data (city names, damage percentages, and look up the US Census data) and put it into an interactive visualization using a Javascript toolkit called D3. If you have a reasonably modern browser (one that supports SVG images), then check it out here:

Firebombs, USA, interactive

One thing you notice quickly when putting it this way is how large some of the metropolises were versus the relatively modest of most of the other cities. The idea of someone bombing out 55% of Sacramento, or 64% of Stockton, or 96% of Chattanooga, is kind of mind-melting. Much less to consider that a New York City minus 40% of its land area would look like.2

You can also see how cramped Japan is compared to the USA (they are at the same scale in the above image, though the projections are a bit tweaked for the layout). Even that could be more emphasized, as the text does: because Japan is so mountainous, its inhabited area is only roughly the size of Montana. So it's even smaller than it looks.

Still, for me it's just remarkable that this mode of visualization would be used in an official publication. These guys wanted people to understand what they had done. They wanted people to know how bad it had been for Japan. They wanted credit. And I get why — I'm not naive here. They saw it as necessary for the fighting of the war. But it also shouldn't have been surprising, or unexpected, to those at the time that people in the future might be taken aback by the scale of the burning. Even Robert McNamara, who helped plan the firebombing operations, later came to see them as disproportionate to the US aims in the war:

This sequence, from Errol Morris's Fog of War, has been one of my favorites for a long time. But it wasn't until recently that I realized its source was one of these maps used for postwar boasting. It's an incredible re-appropriation, when looked at in that light. A document meant to impress an audience, now being used to horrify a different one.

Notes
  1. Regarding the image, I scanned it out of a reprint of the IMPACT issue. Because of the crease in the center of the pages I had to do some Photoshop wizardry to make it even — so there is a lot of cleaning up around the center of the image. The data hasn't been changed, but some of the state outlines were retouched and things like that. Similar Photoshop wizardly was also applied to the Arnold Report image to make it look clean. I suspect that the IMPACT image may have come first and the Arnold report image was derived from it, just because the IMPACT caption goes into details about methodology whereas the Arnold report does not. []
  2. But don't confuse "destroyed" with casualties — I don't have those numbers on hand, though if I can find them, I'll add them to the visualization. The nice thing about D3 is that once you've got the basics set up, adding or tweaking the data is easy, since it is just read out of spreadsheet file. The maddening thing about D3 is that getting the basics set up is much harder than you might expect, because the documentation is really not aimed at beginners. If you are interested in a copy of the data, here is the file. []
Meditations

Who Made That Firebomb?

Friday, August 30th, 2013

My least favorite section in the New York Times Magazine is the insipid “Who Made That?” column. In theory, it’s a great idea for a regular feature. We’re surrounded by gadgets and inventions with rich histories that we never think about. But in practice, the column always dwells on trivial inventions (“Who Made That Loofah Mitt? Sippy Cup? Kickstand?”) and ones with boring stories at that (or, at least, they are stories boringly told). Most of the time, the story is, "some guy thought this was a good idea, then sold it out of his basement for awhile, and then it became successful, and now it is ubiquitous." Snore.1

An E6R2 "amiable cluster" of M69 firebombs, produced by Standard Oil Co.

An E6R2 "amiable cluster" of M69 firebombs, produced by Standard Oil Development Co.

There are a number of things wrong with this approach. One is that it reinforces a notion of the “lone inventor” that wasn’t even very accurate by the late-19th century. Most American inventions (as measured by patents, for example) are generated in collaborative groups by corporations.2 The idea that invention, even American invention, is a product of quirky kooks is a romantic myth. Another issue is that it generally sees all of these as “solitary” instances of invention — rather than the more common cases of incremental development, cross-pollination, and so on. And yet another issue is that most inventions (again, measured by patents or whatever else you want to use as a proxy) are abject failures. That is, almost no patents end up turning a profit, almost no inventions end up being very successful. The Times column generally makes it sound like all one needs is a good idea, and it’ll take off on its own. But the reality is much more weird and idiosyncratic than that. The columns end up being fluffy and trivial without being interesting, which to me is a cardinal sin. I mean, if you need to do something fluffy and trivial to get by, I understand that. But don't be boring about it.

The one good thing about "Who Made That?" is that usually it doesn't focus in on the few "canonical" inventions that everybody likes to talk about. There is some real value in getting away from the standard stories, as usual. We've heard so much about the invention of the atomic bomb. But when was the last time you heard about the invention of the firebomb? Obviously this is because one of these is a technological marvel, improbably created in an impressively short amount of time. I’m not knocking the bomb as the more interesting invention case. But the firebombs are impressive in their own way — and in a very deep sense, the story of their invention is the more shocking one, if only for its banality.

The atomic bomb represents, in a sense, a case of a special almost-one-off invention meant to be something novel and terrible. The firebomb, by contrast, is a weapon developed for a doing terrible things as a regular mode of operation. That is, the moral arguments in favor of the atomic bombs are usually structured in the form of “we had to do this twice in order to achieve a greater good.” It’s harder to do that with firebombs because we used them so many times. It’s one thing to say, “ah, once or twice we had to target large numbers of civilians to make a point.” It’s another to make the targeting of civilians your everyday job, when you start measuring success less by knocking out specific military targets and instead by total area destroyed. So who made that firebomb? A now all-too-familiar mixture of American industry, universities, and government. The list of contractors involved in American incendiary weapons during World War II includes Brown University, University of Chicago, Du Pont, Eastman Kodak, Harvard University, Monsanto, Standard Oil Development, and Stanford University, among others, all working under the auspices of Vannevar Bush's Office of Scientific Research and Development, the Chemical Warfare Service, and other parts of the military.

AN-M69 incendiary bomb

The incendiary raids against Japan dropped numerous types of bombs in different combinations. But the one to focus on, because of its ubiquity and importance in the Pacific theatre, is the AN-M69 Incendiary Bomb. This was a cluster-based napalm weapon created by the Standard Oil Development Company, specifically designed to destroy Japanese civilian houses. The most common cluster assembly (the M19) held 38 individual AN-M69s and would release them 5,000 feet above the target. The wind would catch their parachute streams, moving them apart from one another and orienting them nose-down. (Doing this would also arm the bombs by pulling out their safety plungers.) After impact, the bombs would wait 3 to 5 seconds, seemingly inactive. This is to make sure each one is lying on its side, so that, finally, a stream of burning napalm would be explosively blasted out of the tail: “If unobstructed, the burning fuel charge will travel up to 300 ft horizontally, and when it strikes a surface, the flaming fuel charge smears out producing a mass of flames 6 to 10 ft high.”

Each B-29 could carry 40 clusters in their bomb bays. So that’s 1,520 AN-M69s per plane, and the raids could range from dozens to hundreds of planes. You can do the math, there. Over 40,000 tons of AN-M69s were dropped on Japanese cities during the war. It took about 125 tons per square mile to completely burn out an area of a Japanese city. The AN-M69 had, a once-classified postwar report announced triumphantly, “the highest fire-starting efficiency per cluster, or per ton, or per bomber of any incendiary bomb” developed during the war.3

Clusters of M-69 incendiary bombs rain down over Nagoya, Japan, summer of 1945.

Clusters of M-69 incendiary bombs rain down over Nagoya, Japan, summer of 1945.

The AN-M69 wasn’t the only incendiary bomb. I want to give a quick shout-out also to the E19 Incendiary Bomb, an 11 pound incendiary developed by my alma mater, Harvard University, as a combination of magnesium, oil, thermite, and white phosphorous. It didn’t burn as well as the AN-M69, but had greater penetrating power. But, as the aforementioned report notes, “this factor diminished in importance as the war went on,” presumably because we had stopped trying to directly target troublesome factories and military bases, and had instead moved on to targeting flimsy civilian structures. As a result, “the E19 bomb was never seriously considered for production.” But don’t worry Harvard, you still get some credit in the development of napalm (jellied gasoline) itself, as part of coordinated work with Eastman Kodak and Standard Oil Development. Some 80 million pounds of napalm were produced and used during the war.

Standard Oil Development’s creation of the AN-M69 started in early October 1941 — almost exactly two months before the attack on Pearl Harbor. The initial instigation was to find a way to make incendiary weapons that did not involve large amounts of magnesium, which was in short supply. The work was funded by the Office of Scientific Research and Development. Much of the technical details (horizontal fuse, hexagonal assembly, etc.) are probably mildly interesting to engineers but for the rest of us are probably just of interest in that they are a banal, everyday description of how to develop an efficient weapon for burning lots of things (and people) up.

The "Central German" test structure for the M69 tests. Colorized to highlight fire.

The "Central German" test structure for the M69 tests. Colorized to highlight fire.

The ballistic properties, cluster dispersal patterns, failure rates, and the ability to set various types of target ablaze were, of course, meticulously tested. Reading the developmental history of the firebomb, one finds the names of no individual inventors, only the organizations involved. It is not a history of brilliance or ingenuity, though no doubt there were lots of little brilliant insights along the way. It is, rather, an engineering job. What makes it disturbing is that the engineering is very explicitly directed towards the destruction of civilian life. The main structures they were tested on were mock “German houses” and mock “Japanese houses.” Not factories — houses. 37% of all “German houses” the AN-M69 were tested on were “beyond fire-guard control” within 6 minutes. For the more simple Japanese houses, it was 68%. The results of this testing, the report informs, “were used to make preliminary estimates of the quantities of incendiary bombs required to destroy Japanese cities.”

The effects testing, done very carefully by both universities (Harvard again, along with the University of Chicago), corporations (Standard Oil Development, Texas Company), and the military (Ordnance Department) are also pretty grim. These involved mock bedrooms, with beds and boudoirs and even vanity mirrors, to simulate how effect these weapons would be against “Central German structures,” “experimental Japanese rooms,” and other models of homes. Just in case there was any lingering doubt as to what these weapons were meant to accomplish, and to put to rest the lingering misconception that the destruction of civilian life was an inadvertent consequence imprecise weaponry.

Test of an AN-M69 against an "enemy building model" (Japanese style).

Test of an AN-M69 against an "enemy building model" (Japanese style).

Some 4,400 tons of AN-M69s were dropped on Tokyo during two May 1945 bombing raids, destroying 22.1 square miles. The famous March 1945 raid destroyed 12.5 square miles with only 279 B-29 bombers.4 The area of the Hiroshima bombing where domestic houses were severely damaged was only 8.5 square miles, by comparison.

I don’t want to sound naive about these things. Obviously, World War II was a state of “total war” by all sides, and very little was considered off-limits. But I still feel that too many Americans today don’t take into account exactly what was done in the name of total victory — we still view World War II as the "good war" of the "Greatest Generation." Purposeful mass burning of civilians doesn't usually come into it. At the end of the day, I don't think I really believe in "good wars" — there are wars of necessity, and there are wars of "greater good/necessary evil." I don't think you get any better than that, unfortunately.

Hypertrophic scars and keloids on a napalm-bombed child. I don't know who this is of — I suspect it is from the Vietnam War. It is from SIPRI's Incidenary Weapons (1975), chapter 3, "Thermal effects of incendiary weapons on the human body," without a source listed. It puts a "human face" on these weapons, though, like no other photograph I've seen.

Hypertrophic scars and keloids on a napalm-bombed child. I don't know who this is of, or even when it was taken — I suspect it is from the Vietnam War. It is from SIPRI's Incendiary Weapons (1975), chapter 3, "Thermal effects of incendiary weapons on the human body," without a source listed. It puts a "human face" on these weapons, though, like no other photograph I've seen. There is something about the beauty of the unscarred eye that makes the damage so palpable.

During the war, the inventive forces of the United States went to work to find creative engineering solutions to the problem of burning millions of civilians alive. I really don’t want to use the phrase “banality of evil,” since it has been so over-applied, and I don't really believe in "evil" as a useful historical concept, but there is certainly a terrible banality at work here when one reads about the work that went into crafting these unassuming little bombs. They are so less flashy, as inventions, than the atomic bomb, of course. But that doesn’t make them any less worth our attention. Arguably, it is their “normal-ness” and their easy assimilation into regular military doctrine that makes them more important for us. The more interesting moral questions don’t involve what one would do in exceptional situations, but one does in the every-day.

Notes
  1. For an example of how to do something of this right, take a look at the discussion of the Victorian teapot in Neil MacGregor's A History of the World in 100 Objects. MacGregor manages to take something supposedly mundane — a simple teapot — and use it as a fascinating window into the history of imperialism and globalization. []
  2. See, e.g., David F. Noble, America by Design: Science, Technology, and the Rise of Corporate Capitalism (1977). []
  3. Almost all of my information here comes from “Fire Warfare: Incendiaries and Flame Throwers,” Summary Technical Report of Division 11, National Defense Research Committee, Volume 3 (Washington, DC, 1946). It was originally classified as “confidential.” There is a scanned copy online, along with many other reports on the subject, at the extremely useful website, Japan Air Raids (japanairraids.org). The images of the bombs and tests come from other reports on that page. []
  4. The May 1945 raids had significant number of other types of incendiary bombs as well, though the AN-M69s were the overwhelming majority. The March 1945 raids were almost exclusively AN-M69s. []
Redactions

The Third Core’s Revenge

Friday, August 16th, 2013

By the end of August 1945, there had been a total of three plutonium cores created in the entire world. Everyone knows about the first two. The first was put into the Gadget and detonated at Trinity in July 1945. The second was put into the Fat Man and detonated over Nagasaki in August 1945. The third, however, has been largely overlooked. The third core was the one that was destined to be the Third Shot dropped on Japan, had there been a Third Shot. Instead, it has a different story — but it was still not a peaceful one.1

The magnesium cases for the world's first three plutonium cores. Left: Herb Lehr at Trinity base camp with the Gadget core. Center: Luis Alvarez at Tinian with the Fat Man core. Right: The third core's case at Los Alamos, 1946.

The magnesium cases for the world's first three plutonium cores. Left: Herb Lehr at Trinity base camp with the Gadget core, July 1945. Center: Luis Alvarez at Tinian with the Fat Man core, August 1945. Right: The third core's case at Los Alamos, early 1946.

One of the questions I got from people regarding the "Why Nagasaki?" post I wrote last week was "When would the Third Shot really have been ready?" The reason for the question is that since the Third Shot was unlikely to have been ready by the time Hirohito announced Japan's acquiescence to the American surrender demands (August 15), that satisfies the question of why another one wasn't used. In a very practical sense, it does, but it ignores the fact that Truman actually put a "stop" on all further atomic bombings on August 10 — when the effect (if any) of the bombs on Japan's high command was yet unknown. (He did not, it is worth noting, put a stop on firebombing: huge B-29 raids continued up until the surrender announcement.)

But still, it's an interesting question to consider. There are two components to it: when did they think the third core would be ready, and when was it actually ready? On the first question, we know that on August 10, General Groves wrote to General Marshall that:

The next bomb of the implosion type had been scheduled to be ready for delivery on the target on the first good weather after 24 August 1945 . We have gained 4 days in manufacture and expect to ship from New Mexico on 12 or 13 August the final components. Providing there are no unforeseen difficulties in manufacture, in transportation to the theatre or after arrival in the theatre, the bomb should be ready for delivery on the first suitable weather after 17 or 18 August.2

1945-Groves-to-Marshall

It was on this document that Marshall scrawled, "It is not to be released on Japan without express authority from the President" — the Truman "stop" order. But we also know, from the Seeman-Hull document I discussed in an earlier post, that Marshall was still interested in the atomic production rate on Monday, August 13, 1945. At that time, Seeman claimed that:

Seeman: There's one ready to be shipped now — waiting on order right now. [...] The whole program is phased according to the best production. There is one of them that is ready to be shipped right now. The order was given Thursday [August 9?] and it should be ready the 19th.

Hull: If the order is given now, when can it be ready?

Seeman: Thursday [August 16] would be its readiness; the 19th it would be dropped.

Hull: In other words, three or four day advance notice before it can be shipped, and six days after that when it can be dropped.

So that's a pretty interesting conversation — it tells us that the core was in some kind of almost-finished state by August 13. In a 2012 interview, physicist Lawrence Litz told Alexandra Levy of the Atomic Heritage Foundation that:

Levy: What was—how did—do you remember working on casting the plutonium for the third bomb?

Litz: The particular day that remembers—that remains in my memory was the day that we cast the plutonium for the third bomb because we weren’t sure that the Japanese would surrender even after the second bomb was dropped. We had to cast the atmospheres for the third, and because time was short we had to cast the two hemispheres at the same time. But it was dangerous to cast them in the same laboratory at the same time so we set up two adjacent laboratories with the high vacuum apparatus and the—so we could cast one hemisphere in each one of the two labs.

Levy: How long did that take to cast?

Litz: About twenty-four hours and we had to work straight through.

Which gives some indication of the tenor of the day, and the fact that Truman's "stop" order didn't mean that they weren't expecting to potentially keep atomic bombing. (As does the Seeman-Hull conversation.)

How much plutonium was on hand in August 1945? I've been hunting around for anything that would give me some hard numbers on this, and finally, basically when I'd given up on the effort, I was surprised to stumbled across a document that did:

1945-08-30 - Los Alamos plutonium inventory

"49 Interim Processing Program No. 24," dated August 30, 1945, indicates that by that date that Los Alamos had, by their assessment, received 26.136 kg of plutonium from Hanford.3  Figuring out what was done with all of that requires a little decoding of the terminology. 12.292 kg of the material is listed as having been transferred to the US Army with the notation "HS-1, 2, 3, 4; R-1" after it. I haven't seen this notation before, but I think it's almost certain that "HS" means "hemisphere," i.e. half of a sphere of plutonium. So two full spheres worth were transferred to the Army and were at that time "non-usable," along with "R-1." R-1 is almost certainly an "anti-jet" ring developed for use in the Fat Man core (and not present in Trinity's core).4 So HS-1+HS-2 were the Trinity core components, and HS-3+HS-4+R-1 was the Fat Man core. The first two cores were "non-usable" because they had been detonated.

So we can see from the document that HS-5, HS-6, and R-2 had already been cast and were in the hands of Quality Control at the lab (QC). HS-7 and R-3 had been already cast by then, but still needed hot pressing and nickel coating. HS-8 was scheduled to be pressed on August 31, and finished by September 5. Which is the finest-grain look at the early nuclear production schedule that I've ever seen. (And as you can tell I'm quite proud of myself for finding it and deciphering it!)

But the story of the third core doesn't end there. 

The core was cast sometime around August 13th, but still likely needed to be pressed and coated, ergo the need to take until August 16th to finalize. By August 15th, it became clear that it wasn't going to be needed in the war. So it was kept at Los Alamos.

A mockup of the third core's experimental setup, August 21, 1945. (Source: Los Alamos)

A mockup of the third core's experimental setup, August 21, 1945. (Source: Los Alamos)

What it was doing between August 15th and August 21st, I don't know. But I do know that on August 21st it was being used for critical mass experiments — "tickling the dragon's tail." The experiments in question involved surrounding a full 6.2 kg core with tungsten carbide, getting information about the effect that different tamper arrangements had on criticality. (The tamper reflects neutrons back into the core, thus increasing the overall neutron economy and thus lowering the effective critical mass.)

The experimenter in question was 24-year-old physicist Harry Daghlian, Jr. To quote from a report on the experiment:

[Daghlian] was carrying one brick [of tungsten carbide] in his left hand over the assembly, to place it in the center of the fifth layer. While he had this brick suspended over the assembly, he noticed (from the instruments) that the addition of this brick would have made the assembly supercritical if placed on top of the assembly. Having realized this, he was withdrawing his left hand and the brick from over the assembly and while doing so the brick slipped out of his hand and fell immediately onto the center of the assembly. Knowing that this brick would made the assembly dangerous, he instinctively and immediately pushed this brick off the assembly with his right hand. While doing this, he stated that he felt a tingling sensation in his right hand and at the same time noticed a blue glow surrounding the assembly, the depth of the blue glow being estimated to be about two inches.5

Daghlian was estimated to have received a 510 rem dose of ionizing radiation — a usually lethal dose. He died after an agonizing month. This, incidentally, appears to have been why at the time of the August 30 audit, the core was in Quality Control: they were checking to make sure it had not undergone any "dimensional changes" as a result.

One might think that someone involved with the investigation of the Daghlian accident would be especially cautious around using such a core in further critical mass experiments, even if only for superstitious reasons.

Re-creation of Slotin's fatal experiment with the third core. (Source: Los Alamos)

Re-creation of Slotin's fatal experiment with the third core. (Source: Los Alamos)

But exactly 9 months later, one of the co-authors of the above-cited report, Louis Slotin, would himself receive a lethal radiation dose from the exact same core in the process of yet another (different) critical mass experiment. Slotin knew the experiment in question was dangerous, and had been told by Enrico Fermi that he would be "dead within a year" if he continued to work with such bravado. Like Daghlian, his hand faltered at a literally critical juncture: he was holding a neutron reflector above the core with a screw driver when his fatal slip occurred, lowering the reflector just a fraction of an inch, releasing a stream of neutrons and the characteristic blue glow. Slotin died 9 days later.

The third core, by now nicknamed the "demon core" for having taken two lives, would not go out with a whimper. By some accounts, it found its final disposition in the first postwar nuclear test, shot "Able" of Operation Crossroads, on July 1, 1946,  just under a year after it had been first cast, in that all-night session, in the closing days of World War II. (UPDATED BELOW) Encased in a "Fat Man" assembly with "GILDA" stenciled on its hull, it was finally dropped from a B-29, as it was originally intended to be, and it detonated over a fleet of empty ships in the Bikini atoll, with a yield of 21 kilotons. Alas, the journalists who saw it, with perhaps higher expectations for their first atomic bomb test, incorrectly dubbed it a flop.

The final use of the third core: the Crossroads "Able" shot, July 1, 1946.

The final use of the third core: the Crossroads "Able" shot, July 1, 1946.

That a single plutonium core could go through so much may seem remarkable. But it is a reflection of a time when such cores were extremely rare commodities. And so a single core could simultaneously be the one originally destined for the "third shot," and also be the subject of two fatal criticality accidents, and also still be the first core consumed by postwar nuclear testing. It is a potent reminder of how paltry the American nuclear arsenal once was — when there were less than a dozen pieces of cores, much less cores themselves.

UPDATE: The third core was not used at Crossroads, after all! Learn what happened to it, here.

Notes
  1. Since a few people have gotten confused, I think I should say somewhere explicitly: the Hiroshima bomb, Little Boy, used a 64 kg highly-enriched uranium core. I'm only talking about plutonium here, in part because it was only plutonium cores that were being manufactured at this point, since the Little Boy design was considered more or less instantly obsolete. []
  2. Leslie R. Groves to George C. Marshall (10 August 1945), copy in the Nuclear Testing Archive, document NV0137881. []
  3. C.S. Garner, "49 Interim Processing Program No. 24," (30 August 1945), DOE OpenNet Document ALLAOSTI126018. It is interesting, as well, that the Hanford (W) and Los Alamos (Y) assays were off by 1.376 kg, which is quite a lot in this context (22% of a bomb core, or 44% of a single hemisphere). There are indications in the files that they did quite a lot of sniffing around trying to figure out what each site was doing that led to these different assessments. The problem of Material Unaccounted For never really goes away, but it's interesting that it shows up this early in the game. []
  4. I discussed the fact that the Trinity and Nagasaki cores were slightly different in a very old blog post; Trinity was just two hemispheres, whereas Fat Man also included the ring. []
  5. Paul Aebersold, Louis Hempelmann, and Louis Slotin, "Report on Accident of August 21, 1945 at Omega Site," (26 August 1945), LAMD-120, copy reprinted in John Coster-Mullen, Atom bombs: The Top Secret inside story of Little Boy and Fat Man, rev. 2007. []