Why Nagasaki?

by Alex Wellerstein, published August 9th, 2013

Today is the 68th anniversary of the atomic bombing of Nagasaki. Everyone knows that Nagasaki came three days after Hiroshima — but Nagasaki doesn’t get talked about nearly as much. The reason Nagasaki gets “overlooked” is pretty obvious: being the second atomic bombing attack is a lot less momentous than the first, even if the total number of such attacks has so far been two.

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

A temple destroyed by the bombing of Nagasaki. Original source. Slightly edited to improve foreground/background distinction.

We all know, or think we know, why Hiroshima was bombed. This is because the bombing of Hiroshima is synonymous with the use of the atomic bomb in general. But why was Nagasaki bombed?

I don’t mean, why the city of Nagasaki as opposed to another city. That is well-known. Nagasaki only made it on the list after Kyoto was removed for being too much of an important cultural center. The initial target on August 9 was Kokura, but there was too much cloud cover for visual targeting, so the Bockscar moved on to the backup target, nearby Nagasaki, instead. Bad luck for Nagasaki, twice compounded.

What I mean is: Why was a second atomic bomb used at all, and so soon after the first one? Why wasn’t there more of a wait, to see what the Japanese response was? Was less than three days enough time for the Japanese to assess what had happened to Hiroshima and to have the meetings necessary to decide whether they were going to change their position on unconditional surrender? What was the intent?

There are, unsurprisingly, a number of theories about this amongst historians. There are some that think Nagasaki was justified and necessary. There are also many who agree with the historian Barton Bernstein, who argued that: “Whatever one thinks about the necessity of the first A-bomb, the second — dropped on Nagasaki on August 9 — was almost certainly unnecessary.”1 And there are those, like Tsuyoshi Hasegawa, who don’t think either of the atomic bombings had much effect on the final Japanese decision to unconditionally surrender when they did. (I will be writing a much longer post on the Hasegawa thesis in the near future — it deserves its own, separate assessment.)

The following images are screens taken from footage taken of the Fat Man preparations on Tinian, courtesy of Los Alamos National Laboratory. Above, preparing the final weapon, sealing the ballistic case joints with red Pliobond and blue Glyptol (plastic film). The different colors made it clear that they were properly applied and overlapped.

The following images are screens taken from footage taken of the Fat Man preparations on Tinian, courtesy of Los Alamos National Laboratory. Above, preparing the final weapon, sealing the ballistic case joints with red Pliobond and blue Glyptol (plastic film). The different colors made it clear that they were properly applied and overlapped.

The first is the standard, “official” version — the second bomb was necessary to prove that the United States could manufacture atomic weapons in quantity. That is, the first atomic bomb proved it could be done, the second proved it wasn’t just a one-time thing. One wonders, of course, why anyone would think the Japanese would think the atomic bomb was a one-off thing, or that the Americans wouldn’t have the resolve to use it again. They had, after all, shown no flinching from mass destruction so far — they had firebombed 67 Japanese cities already — and while making an atomic bomb was indeed a big effort, the notion that they would be able to make one and no more seems somewhat far-fetched. The idea that the US would have a slow production line isn’t far-fetched, of course.

What did the participants in the decision to bomb have to say about the use of specifically two bombs? General Groves told an interviewer in 1967 that:

…it was not until December of 1944 that I came to the opinion that two bombs would end the war. Before that we had always considered more as being more likely. Then I was convinced in a series a discussions I had with Admiral Purnell.2

Which, if true, would peg this decision fairly early in the process. In his memoirs, Groves also has this little exchange from just after the “Trinity” test:

Shortly after the explosion, [Brig. General Thomas] Farrell and Oppenheimer returned by jeep to the base camp, with a number of others who had been at the dugout. When Farrell came up to me, his first words were, “The war is over.” My reply was, “Yes, after we drop two bombs on Japan.”3

Both of these, of course, are recollections made long after the fact. And Groves is known to have “smoothed” his memories in order to present him in the best possible light to posterity. The actual instructions for the use of the bomb, from late July 1945, only give detailed information about the first bomb:

1. The 509 Composite Group, 20th Air Force will deliver its first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets: Hiroshima, Kokura, Niigata and Nagasaki. […]

2. Additional bombs will be delivered on the above targets as soon as made ready by the project staff. Further instructions will be issued concerning targets other than those listed above.4

President Truman, in his diary entry, referred to the impending use of the atomic bomb as a singular thing. In his public statements after Hiroshima (which he probably did not write), he claimed that many more atomic bombs would be used until the Japanese surrendered. That being said, he did put a “stop” on any further bombing on August 10th, to wait for a response. This didn’t have any immediate consequences on Tinian, since the next, third bomb wouldn’t have been ready for a few more weeks, and even then, it wasn’t clear whether it would have been immediately dropped or “saved” for a multi-bomb raid.

The bomb prepared, it was then sheathed in canvas and towed out to the loading bay. I find the shot on the right particularly ominous — the second bomb, still a secret, its size and probable importance not quite masked by its shroud.

The bomb prepared, it was then sheathed in canvas and towed out to the loading bay. I find the shot on the right particularly ominous — the second bomb, still a secret, its size and probable importance not quite masked by its shroud.

Oppenheimer, for his part, seems to have expected that both “Little Boy” and “Fat Man” units would be used in combat. In a memo sent on July 23, 1945, Oppenheimer explicitly discussed the expected performance of “the first Little Boy and the first plutonium Fat Man.” Notably, he expressed near complete confidence in the untested Little Boy:

The possibilities of a less than optimal performance of the Little Boy are quite small and should be ignored. The possibility that the first combat plutonium Fat Man will give a less than optimal performance is about twelve percent. There is about a six percent chance that the energy release will be under five thousand tons, and about a two percent chance that it will be under one thousand tons. It should not be much less than one thousand tons unless there is an actual malfunctioning of some of the components.5

Which raises the interesting secondary question of why Little Boy went first and Fat Man went second. Was it because Little Boy was the more predictable of the two? There’s very little about this that I’ve seen in the archives — it seems like it was taken for granted that the gun-type would be the first one. Groves claimed later that the order was just an issue of when things ended up ready to be used on the island, but the components for both were available on Tinian by August 2, 1945, in any event.6

Oppenheimer had, interestingly, earlier suggested to Groves that perhaps they ought to disassemble the 64 kg enriched-uranium core of Little Boy and use it to create a half-dozen enriched-uranium Fat Man bombs. Groves rejected this:

Factors beyond our control prevent us from considering any decision other than to proceed according to existing schedules for the time being. It is necessary to drop the first Little Boy and the first Fat Man and probably a second one in accordance with our original plan. It may be that as many as three of the latter in their best present condition may have to be dropped to conform with the planned strategic operations.7

All of which is to say that the Los Alamos people seemed to assume without question that at least two bombs would be necessary and would be used. At the higher levels, while Truman did publicly proclaim that further atomic bombings were follow, it isn’t terribly clear he was clued in on the actual schedule of those which followed the first. I wonder if his order to stop bombing, issued immediately after Nagasaki (and the Soviet declaration of war on Japan) wasn’t partially a reaction to the fact that he suddenly felt out of control of the military situation over there.

On the left, the bomb being unshrouded, just before loading into the B-29, Bockscar. On the right, the results: the fireball and mushroom cloud, seen through the window of one of the B-29s on the Nagasaki raid, just a few seconds after detonation, roiling and rapidly rising.

On the left, the bomb being unshrouded, just before loading into the B-29, Bockscar. On the right, the results: the fireball and mushroom cloud, seen through the window of one of the B-29s on the Nagasaki raid, just a few seconds after detonation, roiling and rapidly rising.

The historian Stanley Goldberg proposed another theory: that two bombs were necessary in order to justify the decision to pursue both the uranium and plutonium routes.8 That is, Little Boy would justify the (enormous) expense of Oak Ridge, and Fat Man would justify Hanford. To support this argument, Goldberg points out that during the war Groves was completely afraid of being audited by Congress in the postwar. Groves knew he was engaged in a huge gamble, and he also knew he had made a lot of enemies in the process. This is one of the reasons that he meticulously documented nearly every decision made during the Manhattan Project — he wanted “evidence” in case he spent the rest of his years being subpoenaed.9 It’s a clever argument, though it relies heavily on supposition.

Michael Gordin has argued that this entire question revolves around a false notion: that it was known ahead of time that two and only two bombs were to be used. That is, instead of asking, why were two, and not one, used, Gordin instead looks into why were two, and not three, four, and etc. usedGordin’s book, Five Days in August, argues that it was assumed by Groves and the other planners (but not necessarily Truman) that many more than two bombs were going to be necessary to compel Japan to surrender — that the surprising thing is not that the bombing cycle continued on August 9, but that Truman stopped the bombing cycle on August 10.10

Of these options, I tend to lead towards Gordin’s interpretation. The decision-making process regarding the atomic bomb, once the Army took over the production side of things, was that they would be used. That is, not that it would be used, though the importance of the first one, and all of the import that was meant to be attached to it, was certainly appreciated by the people who were planning it. But it was never intended to be a one-off, once-used, anomalous event. It was meant to be the first of many, as the atomic bomb became yet another weapon in the US arsenal to use against Japan. The use of the bomb, and continued bombings after it, was taken by Groves et al. to be the “natural” case. To stop the atomic bombing would have been the unusual position. Go back to that original target order: the only distinction is between the “first special bomb” and the “additional bombs,” not a singular second special bomb.

So “Why did they bomb Nagasaki?” might not be the right question at all. The real question to ask might be: “Why did they stop with Nagasaki?” Which, in a somewhat twisted way, is actually a more hopeful question. It is not a question about why we chose to bomb again, but a question about why we chose not to.

  1. Barton J. Bernstein, “The Atomic Bombings Reconsidered,” Foreign Affairs 74, no. 1 (1995), 135-152, on 150. []
  2. Quoted in Robert S. Norris, Racing for the Bomb: General Leslie R. Groves, the Manhattan Project’s Indispensable Man (Steerforth, 2003), 655 fn. 29. []
  3. Leslie R. Groves, Now it Can be Told (Harper, 1962), 298. []
  4. General Thomas Handy to General Carl Spaatz (25 July 1945),  U.S. National Archives, Record Group 77, Records of the Office of the Chief of Engineers, Manhattan Engineer District, TS Manhattan Project File ’42 to ’46, Folder 5B. Copy online here. []
  5. J. Robert Oppenheimer to Thomas Farrell (23 July 1945), copy in the Nuclear Testing Archive, Las Vegas, NV, document NV0103571. []
  6. Groves, Now it Can be Told, 308. All of the Little Boy components were on the island by July 28. The Fat Man core and initiator were on Tinian by July 28, and the HE pre-assemblies arrived on August 2. []
  7. Leslie Groves to J. Robert Oppenheimer (19 July 1945), copy reproduced in John Coster-Mullen, Atom Bombs: The Top Secret Inside Story of Little Boy and Fat Man. []
  8. Stanley Goldberg, “General Groves and the atomic West: The making and meaning of Hanford,” in Bruce Hevly and John Findlay, eds., The atomic West (University of Washington Press, 1998),  39-89. []
  9. And, in fact, he did end up needing some of those records when he was asked to testify at various times. But the scandals weren’t what Groves had guessed they would be: they weren’t about waste, but about people. Groves ended up drawing on his classified Manhattan Project History file when testifying about Klaus Fuchs and, later, J. Robert Oppenheimer. []
  10. Michael Gordin, Five Days in August: How World War II Became a Nuclear War (Princeton University Press, 2007). []

22 Responses to “Why Nagasaki?”

  1. Lending further support to your preferred interpretation (which is mine as well) is the size of the facilities at Oak Ridge and Hanford, and how officials viewed them once Germany—the original impetus for developing the bomb—had surrendered. The main plutonium and HEU installations at Hanford and Oak Ridge were not designed to prove the concept or build just one or two bombs; they were scaled for mass production.

    In May 1945, as the war drew to a close, there was no disagreement among the key members of the Interim Committee that “the most desirable program” was to continue weapons development and production “as fast as possible” to maintain and expand the presumptive US lead over the Soviet Union (never mind that the Soviets were still our allies).

    In fact, at the Interim Committee meeting of May 31, 1945 (attended by Stimson, Groves, Marshall, Oppenheimer, Lawrence, Bush, Conant, Compton, Undersecretary of the Navy Ralph Bard, Assistant Secretary of State William Clayton, and Secretary of State-designate James Byrnes], Lawrence argued forcefully in favor of continued production, recommending “that a program of plant expansion be vigorously pursued and at the same time a sizable stockpile of bombs and material should be built up” in order to “stay out in front.”

    The operating assumption appears to have been that provided the weapons could be built and had a reasonable chance of working as intended, we would build and use as many as we needed to achieve our military objectives. In that way, they were considered no differently (at least by military planners) than B-29 bombers or any other weapon in the arsenal. They were, at that point, just another kind of bomb, albeit one with unprecedented explosive power.

    • Cthippo says:

      Consider also the German experience of strategic bombing. The British, and later Americans, began bombing German cities in 1939 and continued to do so on a literally daily basis through the end of the war. Rather than slowing war production, the Germans actually managed to increase it throughout the war. In fact, the month with the highest production of German war material was January 1945. and production continued until the factories were occupied by allied forces. Much production was moved underground into tunnels which could not be harmed by strategic bombing.

      Furthermore, while the atomic bombings were impressive, they never came close to the amount of damage and fatalities caused by large scale firebombing missions. Keep also in mind that the cities on the nuclear targeting list were reserved specifically for atomic bombing. The fire bombing campaign had been so effective that there were concerns that there wouldn’t be enough targets left standing to try these weapons out on. Most other cities in Japan had already been firebombed into the ground, yet the Japanese kept producing arms and fighting.

      Given all that, there was no special reason to think that one or two atomic bombs would end the war. Rather, these would have likely been seen as just another tool in the arsenal.

  2. Blake says:

    Can someone quickly refresh my memory as to how much material the government had just after Trinity/Hiroshima/Nagasaki?

    • They were preparing a third plutonium core for shipping to Tinian in a few weeks, and thought they could produce 3 per month from that point onward. So they wouldn’t have had a third ready for use before August 15th anyway. But the key thing here is that they didn’t know the war was going to end then, and, without Truman’s August 10 stop order, they would have proceeded on the idea that they were to repeatedly use atomic bombs from that point onward.

      Instead, Nagasaki became the last time anyone (so far) ever did use an atomic bomb in combat — a much more distinguishing designation than the second time, in my view!

      • Blake says:

        Thanks much. It being that time of year again, the media is vapidly brimming over with either Chomskyite leftist self-flagellation about the bombings on the one hand or Glen Beck ultraconservative jingoistic apologetics on the other, and so the sober, dispassionate, and deeply analytical facts-only approach of this blog is hugely appreciated.

    • Components for at least one or two more “Fat Man” bombs were in the pipeline and fissile material production continiued. See, for example, this interview –

  3. Tony says:

    There’s also the possibility (and I’m not sure where I read this first, Rhodes maybe?) that Hiroshima and Nagasaki where not done as a one-two punch, boom boom, but more as a message to the Soviets; a way to say to them (and anyone else who might try to pick a fight with the US) ‘Listen: We had no problem hitting the Japanese, twice, and we’ll have no problem hitting you as many times as we find convenient. So do not push us.”

    Put another way, Hiroshima was strategic, Nagasaki was a message.

    “Mess with us, and we won’t just hit you when you’re on your way down, we’ll hit you WHEN your down, and we’ll hit you with the biggest rock we can lay our hands on. Get it?”

  4. Bradley Laing says:

    —I hope this is a reasonable question: based on the state of the Japanese Imperial Army in China, and the state of the Soviet Army invading through Manchuria, could you plot on a map where Stalin would be calling the shots in China, by a certain date?

    • Peter Solem says:

      I think what you’re getting at is the question of what caused the Japanese leadership to surrender (to the United States, as opposed to surrendering to the Soviet Union) – which is a different question than what caused the United States to feel that bombing Nagasaki was a necessary step.

      It’s worth recalling that the Joint Chiefs of Staff under FDR were strong advocates of chemical warfare against Japan in the final portion of the Pacific War, particularly in the case of Iwo Jima. FDR vetoed the plan to drench Iwo Jima with poison gas, after the Joint Chiefs had signed off on it – would Truman have instead approved that plan? Would FDR had gone forward with the atomic bombing of Japan, after vetoing chemical bombardment? Would Japan have surrendered to the U.S. without the use of atomic bombs, once they realized that otherwise Japan (like Germany) would end up divided and occupied by both Soviet and American forces? If Stalin hadn’t declared war against Japan, would the Japanese have refused to surrender, even after say, a third atomic bombing? It is also indisputable that the stated reason for pushing forward with the Manhattan Project – that is, to beat the Germans to the atom bomb – had nothing at all to do with the reasons the atom bomb was actually used – was it just an unstoppable juggernaut at that point? Was the thought of not using the product of all that effort unthinkable to Groves et al.? Did Truman really think it would force a surrender, or was he just along for the ride?

      All very interesting questions, but the question of the thinking of the American military system at the time about the need for a second atomic bomb is probably more accessible than the question of what was the thinking of the Japanese leadership at the moment of surrender.

      • Though there is more evidence on the Japanese point of view than I think most people realize. In the near future I plan to write a post on the Hasegawa thesis, which concerns this question very directly. One of the very best points that Hasegawa makes in his work is that there is no single “Japanese” or “American” policy opinion — because both governments involved rather complicated balances of power within their cabinets. There is a more unified “Soviet” opinion in part because of the concentration of power there was within the person of Stalin himself.

    • John F. Opie says:

      It must be remembered that there were a few times before the official begin of WW2 where the Japanese and the Soviets skirmished in Manchuria. In fact, there were over 150 incidents between 1932 and 1934, leading to the Tauran Incident in March of 1936, the Battle of Lake Khasan in July/August 1938 and The Battles of Kalkhin Gol in 1939. In the Tauran Incident, the Japanese trounced the Soviets, in both the Khasan and Kalkhin Gol battles, the Japanese were soundly trounced, with Zhukov’s forces (yes, THAT Zhukov!) effectively destroying the entire Japanese 23rd Infantry Division during the Kalkhin Gol battle. The Japanese were operating relatively light forces at the far end of a poor logistics tail, while the Soviets were operating heavy forces at the far end of a robust logistics tail: this meant that the Soviets would build up their forces, gather their supplies, engage decisively and deliberately, while the Japanese could live better off the Chinese population, could expand their areas of influence (the Chinese army could not match the Japanese in combat) with ease, but lacked the ability to conduct serious stand-up warfare with an opponent with modern weapons.

      This led to the Japanese-Soviet Non-Aggression Pact of 1941, which the Japanese honored even after the Germans invaded the Soviet Union. The Imperial Army of Japan simply had no counter to the mass armored attack supported by aviation assets and large-scale artillery support.

      This is why the Soviet entry into armed combat with the forces of Japan was considered to be such a calamity by the Japanese High Command: while many of their best infantry forces remained in China, the Japanese were facing a military debacle on the level of the destruction inflicted by the Soviets on Army Group Centre on the Eastern Front (i.e. more or less complete destruction of entire divisions and army corps, decimating conventional military forces). Surrendering meant that these forces would survive: if they were engaged by the Soviets, they would have been decimated.

      This gives some insight into the mind-set of the Japanese High Command: the mass killing of civilians did not carry the same weight in their decision to surrender as the risk of losing their army in China.

      • BigGuy says:

        The US Army War College or West Point produced an excellent monograph on Kalkhin Gol. The Red Army wanted to have an overwhelming victory which would keep the Japanese from deciding to attack. They succeeded.

  5. Bradley Laing says:

    Example: “If the Soviet Army siezes the railway yards at [placeholder name], then post-war, Mao and his Comunists will control the provinces of [placeholder name two], no matter what Stalin has already agreed to with us. The war has to end by [palceholder date], or the post-war order will be much worse than planned.”

    • This sort of thing is hashed over in Hasegawa’s book at some length. The short answer is, the uncertainties about the end of the war, the exact character of Soviet participation, and what would be necessary to induce surrender were pretty overwhelming and seem to have prevented anyone from making too much concrete strategy based on such guesses.

  6. Spencer says:

    Yes, I think your interpretation is the best. We must always remember that the atomic bomb was just a continuation of the total obliteration of Japanese cities which had been going along “successfully” without ending the war. Nagasaki was doomed regardless of whether atomic bombs were built.

  7. Periwinkle says:

    I experienced a very unsettling moment of confusion there, seeing Oppenheimer and Groves use “Fat Man” and “Little Boy” to describe whole classes of weapon. Was this usage universal?

    I had always assumed those were nicknames for the two individual bombs. Most “popular” histories imply that this was the case. If that’s an error, it’s a very convenient one, since then the reader doesn’t start asking how many bombs were already in the pipeline when the war ended – and, as you have addressed in previous posts, how many might have been used in anger.

    • John Blankenbaker says:

      Yes, they were design names – IIRC Robert Serber came up with “Thin Man” and “Fat Man”, based on Dashiell Hammett characters, as names for the two different ideas for using Pu.

      Thin Man was a Pu gun assembly and Fat Man was the implosion design. Originally the implosion idea was considered speculative, but Oppenheimer proceeded with it as a hedge.

      When it was discovered that reactor bred Pu was too reactive for a gun design, a U-235 gun design was created. Using uranium made it possible to shorten the overall length of the bomb considerably and so the name “Little Boy” became an obvious (if somewhat sophomoric) choice.

  8. JB says:

    I am a simpleton on this issue.

    Why was Nagasaki bombed?

    Because the Japanese did not adhere to the demands of the United States Government:

    Unconditional Surrender.

    If they had not done so after Nagasaki, I would expect Kokura to be the next target, once the 3rd bomb was fieldable.

  9. […] 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 […]

  10. Warren Platts says:

    I just saw this. Very interesting article, Alex. Your thesis that both types of bombs had to be dropped in order to justify the military-industrial complex of two production facilities makes some sense, but it is also of a piece with the view that the atomic bomb drops were as much of a scientific experiment as anything else. They wanted to see what these new weapons would do–hence the list of cities “saved” from the conventional fire bombing campaign. There was thus no scientific point in dropping an atom bomb on Tokyo–despite the fact that one would think that the Emperor himself would thus be able to see the bomb in action, and so one might be forgiven for thinking that might have a strategic effect on the war!

    So Fat Man had to be dropped in order to see if the design worked, and to compare the effectiveness of the two different types. At the time of early August, production was slow, so to set off Fat Man in a New Mexico desert would have been a “waste” of the only bomb that would have been available after the initial attack. Also, there is the fact that the combat effectiveness of the Fat Man would be better assessed after a drop on an actual city as opposed to an uninhabited desert.

    As for quick one-two punch followed by Truman’s order to “stop” the bombing even though no more bombs were immediately available, that was clearly an attempt to focus the minds of the Japanese leadership. The fact was that another bomb would not be available for another month–or possibly more depending on the contingencies of war. No doubt what happened to the USS Indianapolis was fresh in the minds of the decision-makers. By lighting off both bombs within three days, followed by the apparently magnanimous but in reality disingenuous public “decision” to stop bombing conveyed the impression that the USA did in fact have a stockpile of more bombs on hand that could be used should Japan continued to be recalcitrant.

  11. Peter says:

    I’ve read that quite a few Americans were unhappy with the choice of Nagasaki because it was the only city in Japan with a substantial Christian population.