To demonstrate, or not to demonstrate?

by Alex Wellerstein, published March 6th, 2015

As the atomic bomb was becoming a technological reality, there were many scientists on the Manhattan Project who found themselves wondering about both the ethics and politics of a surprise, unwarned nuclear attack on a city. Many of them, even at very high levels, wondered about whether the very threat of the bomb, properly displayed, might be enough, without the loss of life that would come with a military attack.

1945-06-12 - Franck Report

The Franck Report, written in June 1945 by scientists working at the University of Chicago Metallurgical laboratory, put it perhaps most eloquently:

the way in which nuclear weapons, now secretly developed in this country, will first be revealed to the world appears of great, perhaps fateful importance. … It will be very difficult to persuade the world that a nation which was capable of secretly preparing and suddenly releasing a weapon, as indiscriminate as the rocket bomb and a thousand times more destructive, is to be trusted in its proclaimed desire of having such weapons abolished by international agreement…. 

From this point of view a demonstration of the new weapon may best be made before the eyes of representatives of all United Nations, on the desert or a barren island. The best possible atmosphere for the achievement of an international agreement could be achieved if America would be able to say to the world, “You see what weapon we had but did not use. We are ready to renounce its use in the future and to join other nations in working out adequate supervision of the use of this nuclear weapon.”

They even went so far as to suggest, in a line that was until recently totally etched out of the historical record by the Manhattan Project censors, that “We fear its early unannounced use might cause other nations to regard us as a nascent Germany.” 

The evolution of the "Trinity" test fireball, at constant scale, with the Empire State Building for additional scale reference.

The evolution of the “Trinity” test fireball, at constant scale, with the Empire State Building for additional scale reference.

The idea of a “demonstration” was for many scientists a compelling one, and news of the idea spread to the various project sites. The idea would be to let the Japanese know what awaited them if they did not surrender. This would be more than just a verbal or textual warning, which could be disregarded as propaganda — they would set the bomb off somewhere where casualties would be low or minimal, but its nature easy to verify. If the demonstration did not work, if the Japanese were not receptive, then the bomb could be used as before. In the eyes of these scientists, there would be no serious loss to do it this way, and perhaps much to gain.

Of course, not all scientists saw it this way. In his cover letter forwarding the Franck Report to the Secretary of War, the physicist Arthur Compton, head of the Chicago laboratory, noted his own doubts: 1. if it didn’t work, it would be prolonging the war, which would cost lives; and 2. “without a military demonstration it may be impossible to impress the world with the need for national sacrifices in order to gain lasting security.” This last line is the more interesting one in my eyes: Compton saw dropping the bomb on a city as a form of “demonstration,” a “military demonstration,” and thought that taking a lot of life now would be necessary to scare the world into banning these weapons in the future. This view, that the bombs were something more than just weapons, but visual arguments, comes across in other scientists’ discussions of targeting questions as well.

Truman was never asked or told about the demonstration option. It is clear that General Groves and the military never gave it much thought. But the Secretary of War did take it serious enough that he asked a small advisory committee of scientists to give him their thoughts on the matter. A Scientific Panel, composed of J. Robert Oppenheimer, Arthur Compton, Enrico Fermi, and Ernest Lawrence, weighed in on the matter formally, concluding that: “we can propose no technical demonstration likely to bring an end to the war; we see no acceptable alternative to direct military use.”1

"Recommendations on the Immediate Use of Atomic Weapons," by the Scientific Panel of the Interim Committee, June 16, 1945. The full report (which also discusses the possibility of the H-bomb and many other things) is extremely interesting, as well — click here to read it in its entirety.

“Recommendations on the Immediate Use of Atomic Weapons,” by the Scientific Panel of the Interim Committee, June 16, 1945. The full report (which also discusses the possibility of the H-bomb and many other things) is extremely interesting, as well — click here to read it in its entirety.

I find this a curious conclusion for a few reasons. For one thing, are these four scientists really the best experts to evaluate this question? No offense, they were smart guys, but they are not experts in psychological warfare, Japanese political thought, much less privy to intercepted intelligence about what the Japanese high command was thinking at this time. That four physicists saw no “acceptable alternative” could just be a reflective of their own narrowness, and their opinion sought in part just to have it on the record that while some scientists on the project were uncomfortable with the idea of a no-warning first use, others at the top were accepting of it.

But that aside, here’s the other fun question to ponder: were they actually unanimous in their position? That is, did these four physicists actually agree on this question? There is evidence that they did not. The apparent dissenter was an unlikely one, the most conservative member of the group: Ernest Lawrence. After the bombing of Hiroshima, Lawrence apparently told his friend, the physicist Karl Darrow, that he had been in favor of demonstration. Darrow put this into writing on August 9, 1945, to preserve it for posterity should Lawrence come under criticism later. In Darrow’s recollection, Lawrence debated it with the other scientists for “about an hour” — a long-enough time to make it seem contentious. On August 17, after the bomb had “worked” to secure the peace, Lawrence wrote back to Darrow, somewhat denying this account, saying that it was maybe only ten minutes of discussion. Lawrence, in this later account, credits Oppenheimer as being the hardest pusher for the argument that unless the demonstration took out a city, it wouldn’t be compelling. I’m not sure I completely believe Lawrence’s later recant, both because Darrow seemed awfully convinced of his recollection and because so much changed on how the bomb was perceived after the Japanese surrendered, but it is all an interesting hint as some of the subtleties of this disagreement that get lost from the final documents alone. In any case, I don’t know which is more problematic: that they debated for an hour and after all that, concluded it was necessary, or that they spent no more than ten minutes on the question.2

1945-08-10 - Groves memo on next bombs

As an aside, one question that sometimes gets brought up at this point in the conversation is, well, didn’t they only have two bombs to use? So wouldn’t a demonstration have meant that they would have only had another bomb left, perhaps not enough? This is only an issue if you consider the timescale to be as it was played out — e.g., using both bombs as soon as possible, in early August. A third plutonium bomb would have been ready by August 17th or 18th (they originally thought the 24th, but it got pushed up), so one could imagine a situation in which things were delayed by a week or so and there would have been no real difference even if one bomb was expended on a demonstration. If they had been willing to wait a few more weeks, they could have turned the Little Boy bomb’s fuel into several “composite” core implosion bombs, as Oppenheimer had suggested to Groves after Trinity. I only bring the above up because people sometimes get confused about their weapon availability and the timing issue. They made choices on this that constrained their options. They had reasons for doing it, but it was not as if the way things happened was set in stone. (The invasion of Japan was not scheduled until November 1st.)3

So, obviously, they didn’t choose to demonstrate the bomb first. But what if they had? I find this an interesting counterfactual to ponder. Would dropping the bomb in Tokyo Bay have been militarily feasible? I suspect so. If they could drop the bombs on cities, they could probably drop them near cities. To put it another way: I have faith they could have figured out a way to do it operationally, because they were clever people.4

But would it have caused the Japanese high command to surrender? Personally, I doubt it. Why? Because it’s not even clear that the actual atomic bombings were what caused the Japanese high command to surrender. There is a strong argument that it was the Soviet invasion of Manchuria that “shocked” them into their final capitulation. I don’t know if I completely buy that argument (this is the subject of a future blog post), but I am convinced that the Soviet invasion was very important and disturbing to the Japanese with regards to their long-term political visions for the country. If an atomic bomb dropped on an actual city was not, by itself, entirely enough, what good would seeing a bomb detonated without destruction do? One cannot know, but I suspect it would not have done the trick.

The maximum size of a 20 kiloton mushroom cloud in Tokyo Bay, as viewed from the roof of the Imperial Palace today, as visualized by NUKEMAP3D. Firebombed Tokyo of 1945 would have afforded a less skyscraper-cluttered view, obviously.

The maximum size of the mushroom cloud of a 20 kiloton nuclear detonation in Tokyo Bay, as viewed from the roof of the Imperial Palace today, as visualized by NUKEMAP3D. Firebombed Tokyo of 1945 would have afforded a less skyscraper-cluttered view, obviously.

Of course, the Chicago scientists suspected that as well, but said it was necessary from a moral point of view. Sure, the Japanese might not surrender, but then, at least, you can say you showed them what was coming first.  As it was, we gave no real warning whatsoever before dropping it on Hiroshima. But here’s the question I come to next: could you demonstrate it, and then drop it on a city? That is, could the United States really say: “we have made this apocalyptic weapon, unleashed the atom, and many other peril/hope clichés — and we have chosen not to use it to take life… yet. But if you don’t give in to our demands, we will unleash it on your people.” How could that not look like pure blackmail, pure terrorism? Could they then turn around and start killing people by the tens of thousands, having announced their capability to do so? Somehow I suspect the public relations angle would be almost impossible. By demonstrating it first, they would be implying that they knew that it was perhaps not just another weapon, not just another way to wage war. And that acknowledgment would mean that they would definitely be seen as crossing a line if they then went on to use it.

As it was, that line, between the bomb as “just another weapon” and something “special,” was negotiated over time. I think the demonstration option was, for this reason, never really going to be on the table: it would have forced the American policymakers to come to terms with whether the atomic bomb was a weapon suitable for warfare on an earlier schedule than they were prepared to. As it was, their imagery, language, and deliberations are full of ambiguity on this. Sometimes they thought it would have new implications for “man’s position in the universe” (and other “special bomb” notions), sometimes they thought it was just an expedient form of firebombing with extra propaganda value because it would be very bright and colorful. Secrecy enabled them to hedge their bets on this question, for better or worse.

Without imagery like this, would the world fear nuclear weapons more, or less?

Without imagery like this, would the world fear nuclear weapons more, or less? When, if ever, would the first use of nuclear weapons in warfare have been?

So who was right? I don’t know. We can’t replay history to see what happened, obviously. I think the idea of a demonstration is an interesting expression of a certain type of ethical ideal, though it went so far against the practical desires of the military and political figures that it is hard to imagine any way it would have been pursued. I am not sure it would even have been successful, or resolved the moral bind of the atomic bomb.

I do find myself somewhat agreeing with those scientists who said that perhaps it was better to draw blood with the smaller, cruder bombs, before the really big ones came around — and they knew those were coming. If we didn’t have Hiroshima and Nagasaki, what would we point to, to talk about why not to use nuclear weapons? Would people think the bombs were not that impressive, or even more impressive than they were? I don’t know, but there is something to the notion that knowing the gritty, gruesome reality (and its limitations) is better than not. It took the Holocaust for the world to (mostly) renounce genocide, maybe it took Hiroshima and Nagasaki for the nuclear taboo to be established (arguably). That, perhaps, is the most hopeful argument here, the one that sees Hiroshima and Nagasaki as not just the first cities to be atomic bombed, but the last, but I am sure this is little solace to the people who were in those cities at the time.

  1. This was part of a larger set of recommendations these scientists made, including those which touched on the “Super” bomb, future governance of the atom, and other topics of great interest. Report of the Scientific Panel of the Interim Committee (16 June 1945), 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), Roll 6, Target 5, Folder 76, “Interim Comittee — Scientific Panel.” []
  2. Karl Darrow to Ernest Lawrence (9 August 1945), copy in Nuclear Testing Archive, NV0724362 [note the NTA has the wrong name and date on this in their database]; Ernest Lawrence to Karl Darrow (17 August 1945), copy in Nuclear Testing Archive,NV0724363. []
  3. On the composite core question, see J. Robert Oppenheimer to Leslie Groves (19 July 1945), copy in Nuclear Testing Archive, NV0311426; Leslie Groves to J. Robert Oppenheimer (19 July 1945), Correspondence (“Top Secret”) of the Manhattan Engineer District, Roll 1, Target 6, Folder 5B: “Directives, Memorandums, etc to and from Chief of Staff, Secretary of War, etc.” []
  4. To answer one other question that comes up: would such a demonstration create deadly fallout? Not if it was set to detonate high in the air, like at Hiroshima and Nagasaki. If it was detonated underwater the fallout would be mostly limited to the area around the bomb detonation itself. It would be hard to actually create a lot of fallout with a bomb detonated over water and not land, in any case. “Local fallout,” the acutely deadly kind, is caused in part by the mixing of heavier dirt and debris with the radioactive fireball, which causes the fission products to descend very rapidly, while they are still very “hot.” []

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32 Responses to “To demonstrate, or not to demonstrate?”

  1. Kert VanderMeulen says:

    I think it was in Herbert Blix’s book (but I can’t be positive- I read this a few years ago) that stated that after the Russians invaded Manchuria, Hirohito became convinced that the IJA couldn’t protect the country anymore and that that was a big reason why he wanted to surrender. The officers who inspected the bomb’s damage noted that the effects were felt no more than a foot down into the soil, therefore Japanese citizens should dig shelters to protect themselves from future blasts. The Japanese officers wanted the Americans to invade so that the Japanese could die glorious deaths in battle…

    • This is an interesting and actually quite older debate than most people realize. The United States Strategic Bombing Survey summary report from mid-1946, for example, concluded that “Based on a detailed investigation of all the facts, and supported by the testimony of the surviving Japanese leaders involved, it is the Survey’s opinion that certainly prior to 31 December 1945, and in all probability prior to 1 November 1945, Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.” There are more modern historians who have also concluded this (e.g. Tsuyoshi Hasegawa, Ward Wilson). At some point this year I will post some thoughts about this thesis.

      • Kert VanderMeulen says:

        Yes! I’ve read the survey, too. And didn’t Leahy say that the United States Navy, with a little help from the army (air corps, I presume), had already defeated Japan (with the blockade)? There would have been mass starvation that winter and the emperor would likely have been overthrown- at least he feared a rebellion. And poor Truman- imagine if the Republicans found out that he had spent $2B on a weapon that WAS NEVER USED…

        • Well, it was Roosevelt who spent the money, not Truman. The postwar “what if it doesn’t work” question kept Groves up at night, but I don’t think it did Truman — it never occurred to him not to use the bomb.

          There are complicated historical reasons why the conventional military men liked to dismiss the bomb, especially in the postwar. They feared (for awhile) that it would make them irrelevant, or overshadow their own contributions. So they tended to play it down, rightly or wrongly.

  2. Howard Morland says:

    The key to this whole question is the fact of city bombing. Once you accept a sustained campaign of city bombing as as a valid act of warfare, there’s not much difference between one B-29 with a 20 kiloton nuke and a fleet of B-29s with conventional bombs. We eventually had both, but there were hardly any targets left by the time the nukes arrived on the scene.

    If city bombing ever has a second act, we are all toast.

    The Hiroshima and Nagasaki bombings were militarily and politically irrelevant. They were always going to be “demonstrations,” with the nascent nuclear weapons industry as the prime beneficiary. The only question was who would be under the bombs when they were demonstrated. The answer, of course, was the Japanese cities that had been deliberately spared in order to play that role.

    • What I find interesting, though, is that it is not clear that Stimson really in his gut accepted non-precision city bombing. Which is a separate issue, but I like to bring it up whenever it is asserted that everyone had accepted the morality of strategic bombing — Stimson himself warned Truman that the US could “get the reputation of outdoing Hitler in atrocities” if it kept up a strategy like it did at Tokyo.

      As for them being military “demonstrations,” I agree. And this is the terms in which they targeting planners talked about them: “It was agreed that psychological factors in the target selection were of great importance. Two aspects of this are (1) obtaining the greatest psychological effect against Japan and (2) making the initial use sufficiently spectacular for the importance of the weapon to be internationally recognized when publicity on it is released.”

  3. Ralph Benton says:

    Without doing too much research, I can’t find an example of a new weapon that was demonstrated first, prior to actual use. Poison gas, aerial bombardment, rocket weapons, jet planes, etc., all of these were introduced into warfare without much consideration of a demonstration.

    And as you mention, would it have done any good? I don’t think so. Even if the Germans had first killed a thousand farm animals in an open field with chlorine, the British and French would not have agreed to a cease-fire.

  4. M Tucker says:

    “How could that not look like pure blackmail, pure terrorism?”

    But isn’t that a part of how war works? You pound the enemy and then ask for unconditional surrender while promising to continue the destruction if the answer is no. I really believe that coercion, or blackmail, is a fundamental part of war.

    I have met many people who think the problem is that the lack of a demonstration is equivalent to a sneak attack without a declaration of war; like the attack on Port Arthur prior to the receipt of a declaration or the attack on Pearl Harbor prior to a receipt of a declaration…those darn Japanese, they are really good at that! It always leads to righteous indignation and venomous hate. That is how the people I have encountered who feel strongly that even if a demonstration did not work should have still been tried.

    I know that the scientists were really worried that one or both of the bombs would be a dud. They worried a lot about having one land unexploded and recovered by the Japanese. Didn’t they have some kind of failsafe built in to destroy an unexploded bomb? What if they called for the Japanese to watch a demonstration and nothing happened?

    I agree with you that a demonstration was not really on the table and it is not really clear that the two bombs really influenced the final surrender, even if it was mentioned by the Emperor in his famous speech. I find it very interesting that all of our military leaders did not think dropping the bombs were necessary. Nimitz, Halsey, MacArthur, Eisenhower, Marshall, Leahy, King, not one said it was necessary. I know that Nimitz and Halsey both advocated for a blockade and continuation of “conventional” bombing, if you want to consider firebombing conventional. That might be an interesting counter factual to explore.

    Great Post!

    • The question for me is at what point does that function of war, the politics by other means, become too blatant to coexist with narratives of bringing peace, liberation, good postwar intentions, etc. For a country like the USA, which generally dislikes having to justify its actions with might-makes-right, it presents a troublesome public relations issue.

      As for the failsafes: they did not think Little Boy design would be a dud (even if it failed to detonate exactly correctly it would still probably detonate anyway, because of its simplicity of assembly method), and the Fat Man bomb had scuttling charges in the nose (the four plungers you see in the photographs) that would guarantee at least a “dirty bomb” scattering of plutonium should the firing mechanism fail to trigger. They had high but not unlimited confidence in the bombs going off.

      As an aside, I like to point out that firebombing did have a much lower mortality rate per square mile than the atomic bombs did, even at Tokyo. And Tokyo is the exceptional death count for the firebombing, by a long shot — it accounts for something like 90% of the firebombing deaths during the Japanese campaign, as I understand it.

      • Jonah Speaks says:

        In a book Compton wrote several years later, he said Oppenheimer under-estimated the number of atomic bomb deaths by a factor of four, because he neglected to account for the fact (obvious, ex post) that Japanese civilians would have no warning and would have no time to run for shelter. As a technical point, I do not know by how much atomic bomb deaths could be reduced, if there were (say) a ten-minute air raid warning and shelter to run to.

  5. I would recommend on this subject Richard B. Frank’s Downfall: the End of the Imperial Japanese Empire that contains a detailed description of the debates within the highest levels of the Japanese Army, the Imperial government, and the Emperor’s inner circle in August 1945. Frank judges that the Soviet invasion was not decisive because the leadership of the Army and the Emperor did not initially realize the extent of the collapse of Japanese defenses in Manchuria. Frank notes that when the Emperor intervened decisively in the early hours of 10 August he explained his decision to his leadership citing Japan’s internal situation (collapsing morale from the blockade and bombing) and two military considerations: inadequate preparation to resist invasion and the vast destructiveness of the two atomic bomb attacks along with the toll from conventional bombing. He made no reference to the Soviet intervention.

    On 14 August in further discussions with his military leadership he cited the enemy’s “scientific power,” a reference to the atomic bomb, and the Soviet intervention. This was his only reference to the Soviet intervention he made in this period and it is joined with the atomic bomb. In his Imperial Rescript broadcast to the Japanese people on 15 August announcing his decision to end the war the Emperor spoke explicitly on only one point, the enemy’s use of a “new and most cruel bomb, the power of which to do damage is indeed incalculable, taking the toll of many innocent lives.” There was no reference to Soviet intervention. Six months later the Emperor dictated a lengthy statement, Showa Tenno Dokuhakuroku, on his role in the decision to surrender. This statement was kept secret and not released until after his death in 1989. In it he mentions a number of concerns that motivated his decision including fear the Japanese race would not survive a prolonged war, fear for the survival of the national polity, and fear of American capture of sacred symbols of the divine status of the Imperial line. The Soviet intervention is not cited as a specific concern.

    • I know Frank’s book, but there are other books as well, with other evidence. It is a complex issue of archival record and interpretation, not to be resolved in a blog comment discussion.

    • Itaru Kaneko says:

      I almost agree with quotation of Frank’s book.

      Probably soviet intervention also contributed. And probably all other factors are considered within military leadership even they were not explicitly reffed. But A-bomb was indeed a big part of that.

      I would like to add how exceptional was that debate. Like Canadian governor, Japanese Emperor usually does not participate politics at all. When government and highest circle of military, could not reach to a consensus on the surrender, PM Suzuki asked emperor’s opinion as a final choice, at the very end of the meeting. It was probably the only case of asking opinion of the Emperor. In that sense, A-bomb also changed the form of highest circle.

      Same as most of Japanese, I hope such thing never happened. In same time, I understand that there were more victim in Asia and probably I doubt that demonstration was better for Japan.

  6. Gene Dannen says:

    Excellent post, Alex. It raises so many issues, I hardly know where to begin.

    Leo Szilard, who had thought longest and most deeply about these issues, changed his view during the war. In a January 14, 1944 letter to Vannevar Bush, he wrote that the postwar peace would depend on the fact that “atomic bombs have actually been used in this war and the fact of their destructive power has deeply penetrated the mind of the public.”

    By the spring of 1945, he had seen further. He saw that the bombs would be used on cities. And he realized that to murder vast numbers of innocent civilians in the hope that it might make repetition of the crime less likely was immoral. The deaths would be certain. The future benefit was only hypothetical.

    I think you give the wartime decision-makers too much credit in suggesting that their statements about the bomb were trying to preserve ambiguity. I think that any ambiguity reflects only their muddled thinking. As they marveled at the power of the bomb, the vast ocean of its implications lay undiscovered all around them.

    As for the common perception that Hiroshima and Nagasaki created a moral barrier to future use of the bomb, I think that there is more truth to the opposite view. All the war-planning of the nuclear arms race was based on the assumption that using nuclear weapons on cities was legitimate. In other words, the nuclear arms race was predicated on the precedents of Hiroshima and Nagasaki. To this day, the USA hasn’t renounced or condemned such use.

    • Thanks for the feedback, Gene. I am not trying to say they were trying to preserve ambiguity actively — I am saying what you are saying that their own thinking was ambiguous and not yet “settled.”

  7. Krepon says:

    Another fine post, Alex.
    I am a fan of John Dower’s work. I recommend Embracing Defeat: Japan in the Wake of World War II.
    The argument that doesn’t show up very much in these debates, but that I find persuasive, is this: Truman, Stimson and the rest were intent to do their utmost to end the war as quickly as possible. They, more than anyone, were acutely aware of the casualty counts. And what was in store the longer the war in the Pacific dragged on. Any argument that would have delayed a surrender would have been — and was — a very tough sell.

    • Hi Michael: I hope you are well! While there is no doubt that they wanted a swift end to the war, there is the question of how much they thought the atomic bomb would help with this, and how to optimally achieve this, and how to weigh that need against all of their other desires (e.g. re: the demands for unconditional surrender, which is an area where Stimson and Truman disagreed deeply). It is a complex issue, and they were trying to come up with the right solution for both the near and far time horizons.

  8. Charles Day says:

    I wonder: Did the US consider nuking an already devastated city like Tokyo or Osaka as a demo?

    • The Target Committee ruled out nuking already-bombed cities because they didn’t think it would provide much “demonstration.” And I would note that Tokyo was still probably the most populous city in Japan in 1945 (3 million or so), even after all of that bombing and death.

  9. Peter says:

    Wasn’t there discussion about using the first bomb on a Japanese naval base on one of the Pacific islands?

    • In 1943 and 1944, there was discussion about possibly using it against Truk/Chuuk lagoon, a Japanese naval base. By 1945 however Truk had been neutralized as an important target.

  10. Jonah Speaks says:

    Also in the Franck report is this sentence: “After such a demonstration the weapon could be used against Japan if a sanction of the United Nations (and of the public opinion at home) could be obtained, perhaps after a preliminary ultimatum to Japan to surrender or at least to evacuate a certain region as an alternative to the total destruction of this target.”

    Since Japan was not scheduled to be invaded until November 1, 1945, there was a three-month period during which domestic and international opinion could be queried on whether and how to drop the bomb. Demonstrating the bomb and then opening the matter up for public discussion would have been the better procedure.

    Also of interest is the proposed option for Japan “to evacuate a certain region as an alternative to the total destruction of this target.” Read literally, one can see the germ of an idea to accept evacuations as a substitute for nuclear bombing. This suggestion is not further explained or described in the Franck report.

    My strong suspicion is that the evacuation idea came from Leo Szilard, one of three authors who wrote the report (3 wrote, 7 signed). Szilard later advocated the idea to give a city two or four weeks warning, so evacuations could take place, and then bombing the city. Szilard’s later development of his idea modifies the idea significantly, since evacuations would be merely a prelude to bombing, not a substitute for bombing.

    Both versions of the idea would save lives, and so have moral and humanitarian value. Accepting evacuations as a substitute for bombings is the superior version, because it also saves property, and leaves intact a place for people to return to after a cease-fire is agreed to. A nuclear war need not kill anyone at all, if nuclear-armed nations are prepared to accept evacuation orders as a substitute for nuclear bombings.

    • Kert VanderMeulen says:

      I wonder how much of the decision-making process was driven by all attempts to keep the bomb’s nature from Russia. At Potsdam Truman was almost gleeful that he could dangle the promise of a war-ending weapon in front of Stalin. Of course Uncle Joe played coy- he already knew. But irrational fear of the Soviet Union and its system, which led to decades of poor US policy decisions, had to be considered by the “men in the room” when deciding on a demonstration. Perhaps they were more concerned about firing a dud in front of the Russians than they were about firing a dud in front of the Japanese. And perhaps they reasoned that a city of charred bodies and flattened buildings caused by one bomb would send a stronger message to Moscow than to Tokyo.

  11. Raymond Takashi Swenson says:

    During an Air Force training course, I learned that of the first 9 Plutonium “implosion” bombs, only the first two–Trinity and Nagasaki–and one more, had a nuclear explosion. The implosion mechanism was still imperfect. If the second bomb had fizzled, as later bombs did, it might have been a negative demonstration. There were still die hards in the Imperial Army who did not want to surrender, and occupied the palace grounds to find and destroy the wire recording of the emperor’s surrender announcement.

    • Whomever told you that was either confused or mistaken — all of the Mk-III Fat Men bombs tested were successful. Trinity, Nagasaki, Crossroads Able, and Crossroads Baker were all the same design and all worked fine. Similarly the tests in 1948, which were of optimized bomb designed. The first fizzle bomb test did not occur until 1951, and it was an attempt at a much more radical bomb design. It is true that they were not sure how well the implosion bomb would work in 1945. But they were extremely confident of the Little Boy bomb, which could have been the demonstration bomb.

  12. Thank you for such an interesting article. I can’t help but wonder, if the U.S. had detonated the bomb for demonstration, what type of signal that would have sent to our allies. Too whom would they be demonstrating this too, and for what purpose.
    Secondly, the Japanese did not surrender to the Soviets after the Manchurian invasion, they did not surrender to the British, they surrendered to The United States of America. Japan had to deal with the might of the U.S forces from the Coral Sea to Nagasaki. Soviets in Manchuria was a problem. The U.S. dropping nuclear weapons, and invading the Homeland meant the end of a country. It was the U.S Navy that was permitted to float into Tokyo Bay in September of 1945.

    • Just a quick note: the “they surrendered because of the Soviets” theory argues that they surrendered to the Americans because they didn’t want to end up a divided state, like Germany. In that argument, the Soviet invasion breaks the deadlock in favor of those seeking a diplomatic (as opposed to military) end of the war, because the consequences otherwise would be destined to destroy the Japanese state. If the US could be persuaded to allow the Emperor system to remain in some form, then Japan qua Japan would still exist, and they knew Stalin would never give them that kind of deal. Not saying I agree with that, but just fleshing that out.

  13. Will Thomas says:

    Hi Alex,

    On the subject of who would be the proper experts to consult on the likelihood of Japanese surrender, it seems likely that almost anyone’s opinion would be impressionistic.

    There were some high-level discussions in Britain when the RAF committed to bombing cities in 1941-42. Some scientists argued that not only was bombing incapable of causing catastrophic economic damage to Germany, but the morale effects were unlikely to match anticipations. This was based on a survey of residents of (I think) Birmingham and Hull, who were hit heavily during the Blitz, and their resilience. There was also discussion of the effects of bombing in Abyssinia, of Japan in China, and in Spain. Most subsequent discussion revolved around the anticipated effects on the war effort, but in the minutes of a high-level meeting in November 1942, we find this argument:

    “There was, however, one strong argument in favour of this heavy air offensive which had not yet been mentioned; piecemeal devastation of German cities would bring the horrors of home to the German people in a way that had not hitherto been possible. They might in this way be made to realise that aggression did not pay.”

    That sort of argument would tend to negate the importance of the British experience. Of course, these questions have been debated for many decades, and the general consensus seems to be that British bombing policy was mainly a function of prewar doctrines anticipating the devastating effects of bombing, which were entrenched in the politics of the RAF as an independent service; and in the imperative to show support to the Soviets. Updated studies of the effects of bombing would generally have been subordinated to those established motivations.

    In the American case, I’ve run into a July 1945 study by political scientist Quincy Wright, “Historical Studies of Casualties,” which attempted to correlate casualty counts with capitulation in historical wars. Wright had already published a macro-historical comparative study of wars in 1942, A Study of War. I’m pretty sure this sort of study was inconsequential for policy, but it suggests that, at this time, the social-political dynamics of war were considered a pressing, unresolved problem, certainly academically.

    In a notorious incident, the RAND Corporation later studied the circumstances of capitulation, including under what circumstances the US might consider capitulation – when this was learned by Congress, there were moves to defund the Air Force’s RAND contract.

    Anyway, these are all isolated data points in a much larger picture of historical thought that remains to be synthesized. But it seems like something that can be profitably brought into the picture here.

  14. Will Thomas says:

    On your point about whether, by issuing a demonstration, the US would have been delineating an ethical line, which they might later be forced to cross in an indefensible way, I don’t quite see things the same way.

    My sense has always been that the US-British response to the style of war in World War II – and particularly direct attacks on civilians – was that this kind of war was immoral, but that it had become necessary to avoid greater evil.

    This view of the immorality but necessity of modern war makes possible the idea of the atomic bomb as simply another military weapon, like incendiary attacks. Since it was simply another weapon, that would negate the need to issue any sort of demonstration. This was clearly the prevailing military point of view.

    At the same time, though, it makes it possible to regard the atomic bomb, as a clearly delineated step in an escalating insanity. For the Japanese, offering a demonstration would give them a well-defined opportunity to avoid a new phase in the devastation of their country. For the Americans, offering a demonstration would afford an opportunity to step back from the escalating immorality of war. However, if the Japanese did not respond to the opportunity to surrender, taking that step would not have been morally compromising, because the essential dividing line between morality and immorality in warfare had already been crossed.

    I can see how this sort of position could be regarded as a peculiarly “scientists'” position, because they would regard themselves as having a much keener appreciation of just why the atomic bomb could be regarded as a clearly delineated step in warfare, where the military would regard it as a munition that was highly comparable to an incendiary raid—thus justifying the Chicago scientists’ sense of the need for their intervention.

    This, of course, is a rather condescending view of military thinking, and I suspect Oppenheimer, who worked closely with Groves and other military personnel, would have regarded it as such. He would have known that they would have already taken into account (and already rejected as insufficiently consequential) the peculiar features of the atomic bomb as a kind of display.

    Anyway, that’s my understanding of that question.

    • Ross Mallett says:

      You bring up a point that is often overlooked: the US and Britain had different styles of war in World War II. Particularly in regard to the idea of terror bombing; the British were proponents of what we now call the “shock and awe” concept, of psychological war. Lord Penney served on the targeting committee that selected Hiroshima, and one of its findings was “that psychological factors in the target selection were of great importance”.

  15. Hugh Gusterson says:

    Your final argument in this post (that it was better for posterity to show what the bomb could do to a city) is the same as Philip Morrison made in a guest lecture in my class.

    • Gene Dannen says:

      If the time for such a decision comes again, we can hope that the single individual making the decision chooses to see Hiroshima that way — as a warning rather than a precedent. But who will that person be? And will they? Or not…