Harry Truman claimed, in his July 25, 1945 diary entry, that:

I have told [Stimson] to use [the first nuclear bomb] so that military objectives and soldiers and sailors are the target and not women and children. Even if the Japs are savages, ruthless, merciless and fanatic, we as the leader of the world for the common welfare cannot drop this terrible bomb on the old Capitol or the new.

He & I are in accord. The target will be a purely military one and we will issue a warning statement asking the Japs to surrender and save lives.

And in his August 9 radio address, he said:

The world will note that the first atomic bomb was dropped on Hiroshima, a military base. That was because we wished in this first attack to avoid, insofar as possible, the killing of civilians.

Supposedly he only found out it was a city when they got reports from Japanese of 200,000 dead.

In "The Decision to Use the Atomic Bomb," Harper's, 1947, Stimson says that he decided to use a "dual target plant surrounded by or adjacent to houses and other buildings most susceptible to damage," and to use it "without prior warning." He also that, on some unspecified date between July 16 and August 9, "I approved four other targets including the cities of Hiroshima and Nagasaki."

Could Truman really have been ignorant of the fact that Hiroshima was a city? Is there evidence as to whether he was misled on this point by Stimson? Is there evidence that he was lying in these statements? Or that he was engaging in self-deception to salve his conscience?

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    Can you source the contention that he did not know that it was a city?
    – justCal
    Oct 14, 2017 at 0:15
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    Did Hiroshima not contain significant military facilities? And was there any military base large enough that the effects of the bomb could be confined to it?
    – jamesqf
    Oct 14, 2017 at 3:28
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    @user2448131: Can you source the contention that he did not know that it was a city? That's what the two quoted passages seem to indicate.
    – user2848
    Oct 14, 2017 at 11:44
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    Question based on false assumptions: Hiroshima was a military base, hosting the military headquarter of the army protecting Western Japan. Everyone knew it was a city, too, obvious from the target size.
    – Greg
    Oct 14, 2017 at 17:45
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    I would be of the opinion (hence not an answer) that Truman's diary would reflect his thoughts. If he wrote in his diary that he directed a military target, and that he only later learned it was a city, then he thought they would only target a military installation. I am also of the opinion that there was no way for Truman to have a mental concept of what the atom bomb would actually do. It was, to him, simply a bomb. OK, a large one, but still a single bomb. There would have been no way for him to grasp the actual magnitude.
    – CGCampbell
    Feb 27, 2019 at 16:30

3 Answers 3


I think we may be operating from a misconception, that the diary entry concerning that the 'target will be a purely military one' and that the statement that 'Hiroshima, a military base' imply Truman did not understand the presence of a city.

The target selection process had been going on for some time. A lot of documents are available and the discussion on narrowing down the city to be bombed can be read National Security Archive-George Washington University. This defines Hiroshima

"This is an important army depot and port of embarkation in the middle of an urban industrial area. It is a good radar target and it is such a size that a large part of the city could be extensively damaged."

(emphasis mine) This was dated May 12 1945. Hiroshima was one of two AA rated targets, the other being Kyoto(a city of 1,000,000 at the time). Hiroshima was selected for its military value. From the wiki (and I know there are many different casualty estimates):

directly killing an estimated 70,000 people, including 20,000 Japanese combatants

and this entry from Yale Law School discusses the military significance of Hiroshima:

Hiroshima was a city of considerable military importance. It contained the 2nd Army Headquarters, which commanded the defense of all of southern Japan. The city was a communications center, a storage point, and an assembly area for troops. To quote a Japanese report, "Probably more than a thousand times since the beginning of the war did the Hiroshima citizens see off with cries of 'Banzai' the troops leaving from the harbor."

So the military effect is established. There were military casualties. The military base existed.

I don't see a problem characterizing Hiroshima, in the radio address of Aug 9, as a military base. (on a side note, if you ask someone in the military where they were stationed, a typical reply might be 'San Diego' for instance-not 'Naval Base San Diego') In the radio address I doubt there was any thought that the public would have any idea where or what Hiroshima was. The term 'a military base' is just descriptive.

Concerning the possibility of Truman being deceived concerning the nature of this target let's take a look at this quote from the page on the target selection:

a large part of the city could be extensively damaged.

It seems to me this portion of text says a lot. It acknowledges the presence of the city, but seems to show a lack of understanding concerning the power of the weapon they are about to unleash. A 'large part', 'could be',and 'extensively damaged' all express uncertainty at the range,the outcome, and the amount of damage.

If we look at the first part of the above mentioned diary article, it discusses the information concerning the weapon test.

An experiment in the New Mexico desert was startling — to put it mildly. Thirteen pounds of the explosive caused the complete disintegration of a steel tower 60 feet high, created a crater 6 feet deep and 1200 feet in diameter, knocked over a steel tower 1/2 mile away and knocked men down 10,000 yards away.

A crater 1200 feet in diameter. A crater this size would destroy a few city blocks, but 1/2 mile away it just knocked over a test structure. This test is what they keep mentioning in later references.

The Truman library has a lot of documents, concerning tests, target selection, ect. The last couple pages of one document has some related reports from after the bomb was dropped, both of which express surprise at the results, and compare to the first test (emphasis mine):

letter from Admiral Edwards to Admiral Leahy, 6 Aug

"visible effects greater than any test"

letter from Stimson to Truman, also 6 Aug

..."first reports indicate complete success which was even more conspicuous than the first test.

There is no doubt that there were military objectives at Hiroshima. I don't think there were any illusions that there would be no civilian casualties. But it appears from the documents, that they were in no way expecting to completely destroy an entire city (possibly 'extensive' damage), and that they were all surprised by the results (since they kept comparing results to the earlier test detonation, which was minor in comparison).

So concerning the 'purely military' nature of the target. The target was the military facility at Hiroshima; the expectation was its destruction; and they understood there would be collateral damage(I hate that term),but not its vast extent . This was the 'purely military' aspect of the selection of this target. If he did not desire a military target, Kyoto with its population of 1,000,000 would have likely been selected (the other AA rated target),to not minimize but to maximize civilian casualties, and the horror of this moment in history would have been (if possible) greater yet.

(I hope this somewhat clears up the last half of the answer. My goal was to show that the massive casualties may have been unexpected, since the individuals involved all kept thinking and comparing to the original test. This, combined with the fact that they rejected targets which contained more civilians, shows the consideration which makes this target 'military' in nature. Its not that the target would cause only military casualties, but that the reason for the selection of this target over others was due to its military nature.)

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    There is some interesting material in this answer, but I'm having trouble putting together what you're claiming. Truman said, "The target will be a purely military one[...]" You quote it, and I quote it, but I don't understand what you're claiming about it. The second half of the answer seems to drift off topic. Is this material connected to the question and to the rest of the answer? If so, then maybe you could make those connections more explicit.
    – user2848
    Oct 15, 2017 at 6:40
  • @BenCrowell The latter part details the divergence between a potentially purely military target and the massive civilian effect. It suggests 20,000 soldier were targeted but that some portion of the civilian deaths and devastation was unexpected. "Purely" still seems out of place since it was expected to damage infrastructure, but maybe there is some distinction between primary intent versus and expected outcome.
    – user22111
    Oct 15, 2017 at 10:05
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    I apologize for the 'drift'. But @notstoreboughtdirt has the idea I was trying to express. I was trying to show that in these peoples' planning, they kept referencing the test blast, which was relatively small. I think it was possible in their minds that they were targeting the military establishment. The sites they eliminated from consideration show that had the death toll been the primary concern then Kyoto, with 5 times the population, would have been selected, as it was the only other AA target listed. I'm running out of comment space. I will try to clarify the answer.
    – justCal
    Oct 15, 2017 at 13:45
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    It's also worth mentioning that they had no real conception of the effect of the heat and light from the explosion on the surroundings. With chemical explosives the blast produces the damage -- note how in their discussion of the effects of the Trinity test they are focused on blast damage, not on the effects of the heat radiation. I suspect that they expected to make a big crater and blow down buildings further out, but not to badly burn people in the open a mile away. It was too far outside their ken for them to really understand the detailed effects.
    – Mark Olson
    Feb 1, 2019 at 20:57
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    @Ben Crowell You may well be right, but I don't think that the results from Trinity could have possibly had the visceral impact that photos from Hiroshima had. It's one thing to know facts and it's another to feel their reality. It's very hard for someone who grew up post-WW II to appreciate what a different country the past is in that respect.
    – Mark Olson
    Feb 3, 2019 at 22:43


Timeline of 1945:

  • Feb - firebombing of Dresden
  • Feb/Mar - battle of Iwo Jima
  • Apr 12 - Truman becomes president.
  • May 30 - Groves and Stimson begin to butt heads over targeting Kyoto.
  • Jun 16 - committee rejects a demonstration bombing
  • Jul 16 - Trinity test
  • Jul 25 - Truman's diary entry
  • Jul 30 - torpedoing of the Indianapolis
  • Aug 6 - Hiroshima bombing

The Allies started out by trying to use precision bombing against Germany, but they found this difficult to do, so they changed to carpet bombing. This set a precedent and put military brass and politicians in a mind-set where there was no longer any real pretense of trying to spare civilian lives. The Battle of Iwo Jima convinced military planners that an invasion of the Japanese homeland would be incredibly costly. Against this backdrop, there was irresistible momentum for using the two available bombs on one or more Japanese cities, and opponents like Szilard were sidelined.

When Truman became president, he knew nothing about the bomb and had to have it explained to him. He was not closely involved in targeting decisions. The main people involved were General Groves and Secretary of War Stimson, who was 77 years old. A committee began discussing targeting on May 30, which was before the Trinity test. At this point, the explosive yield of the bomb was highly uncertain. There was a betting pool (Rhodes, p. 656) among six of the top physicists as to the yield of the Trinity test, with people betting on figures of 0, 0.3, 1.4, 8, 18, and 45 kilotons. This meant that while the targeting decisions were being made initially, there was so little knowledge that nobody could actually project civilian versus military casualties, or the effect to be produced by dropping the bomb in one spot versus another.

The torpedoing of the Indianapolis, with men dying horrible deaths in shark-infested waters, hardened attitudes toward the Japanese. A committee had rejected a demonstration bombing, which was associated with the idea of putting bombs under international control. These hardening attitudes were to some extent vindicated after the Hiroshima bombing, when George Marshall was shocked to find that one bomb hadn't even been sufficient to convince the Japanese to surrender unconditionally (Rhodes, p. 736).

The debate over targeting Kyoto

Before FDR's death, Groves and Stimson began an ongoing battle as to whether to target Kyoto. Stimson wanted to preserve the historic city, for reasons that continue to be debated, while Groves wanted to target it. This battle went on for a long time, so basically any possible debate as to military versus civilian targets never really happened, because it was diverted into this channel. Truman seems to have been involved in the whole targeting discussion only because Stimson kept invoking Truman's support in Stimson's pet cause of not targeting Kyoto.

The criteria used for targeting do not really appear to have included any consideration of Japanese civilian deaths. They were concerned with not killing American POWs (there were none in Hiroshima) and with using targets that had not yet been hit by conventional bombing -- a pristine target would make it easier to determine afterwards what the nuclear bomb's effect had been.

Reading Rhodes, I felt confused about why Stimson didn't want to bomb Kyoto. Wellerstein has an interesting discussion of this, and seems to indicate that historians are puzzled by this as well. Stimson had visited the city during the US occupation of the Phillipines, and may have gone there on his honeymoon. Kyoto had historical and religious significance (Wallerstein, Kelly, Malloy). Kyoto was a tempting military-industrial target (hence Groves's desire to target it), but according to Kelly's analysis Stimson probably wanted to spare the city in order to minimize Japanese anger and resistance, which he believed would be excited by the destruction of a historical and religious site. Malloy seems to agree with this, citing a couple of relevant lines from Groves's autobiography.

Truman's character

There is clear evidence, from after Hiroshima, for a picture of Truman's feelings of guilt, emotional dissembling, and lack of understanding of the technical issues. Oppenheimer and Truman met for the first time on Oct. 25, 1945. My info on this meeting is from Bird and Sherwin, pp. 331-333. Oppenheimer was shocked by Truman's ignorance when Truman claimed that the Russians would "never" be able to build a bomb. Oppenheimer wrung his hands and said, "Mr. President, I feel I have blood on my hands." Truman became very angry about this. This clearly had hit a sore spot. On the one hand, Truman embellished the story later to make himself come out looking tough. On the other hand, he later muttered to himself about having blood on his own hands. The Bird-Sherwin biography quotes contemporaries' opinions of Truman re the nuclear issue on p. 333: that he was "small-minded" and "a simple man." They summarize these common impressions by saying that "Truman's instincts, particularly in the field of nuclear diplomacy, were neither measured not sound--and sadly, certainly were not up to the challenge the country and the world now faced."

A hypothesis about Truman

So I think the basic story here is that the decision was set on track to bomb one or more cities during a period when Truman didn't know about the bomb, and by the time Truman became president, the debate had already been channeled into a decision between Kyoto and other targets. Little was known yet about the yield of the bomb, and Truman understood even less of the technology. He didn't attempt to question the decisions of people who had already been running the bomb project before he heard about it.

Regardless of how passive, uninformed, and uninvolved he was on the targeting issue, he can't possibly have been ignorant of the fact that Hiroshima was a populated city. His diary entries show that he was at least involved and informed enough to have been conscious of the debate about Kyoto. His diary entry shows a cursory moral struggle with the fact that, given the yield measured in the Trinity test, he would clearly be killing something like 100,000 people. This was probably less a real personal struggle than an attempt at test-driving his propaganda for use after the bomb was dropped. His propaganda (and/or self-propagandizing) made use of absurd rationalizations: that Hiroshima was "purely" a military target, and that by targeting Hiroshima rather than Kyoto they were taking some kind of moral high ground.

A more detailed but more uncertain story-line that seems at least plausible to me is the following. This is supported by Kelly and Malloy. Stimson, an experienced imperialist, wanted to spare Kyoto out of cold-blooded calculation regarding the postwar tractability of Japan as a US dependent. Because of this, he made various cynical and specious arguments to Truman, e.g., exaggerating Kyoto's status as a civilian target and Hiroshima's importance as a military target. Truman was incurious and not very smart, and possessed nothing like Stimson's extensive personal experience in Asia. He took the bait and exaggerated the spurious distinction in his own mind in order to self-propagandize and publicly propagandize about US morality. Because the bombing plan had been a long time in the building and had such momentum, it would have taken tremendous moral and intellectual authority, energy, and self-assurance to turn it aside in any significant way. Truman did not have those qualities in such exceptional quantities. However, he did have the moral qualms about mass killing that any non-psychopath would have had, so he needed rationalizations. Stimson gave him one.

In support of this interpretation, it appears that professional historians have also seriously considered the hypothesis that the decision makers were "self-deluded." See Kelly describing Sherry's opinion of Stimson.


Rhodes, The making of the atomic bomb

Bird and Sherwin, American Prometheus: The trumph and tragedy of J. Robert Oppenheimer

Jason M. Kelly, “Why Did Henry Stimson Spare Kyoto from the Bomb?: Confusion in Postwar Historiography,” Journal of American-East Asian Relations 19 (2012), 183-203

Sean Malloy, “Four Days in May: Henry L. Stimson and the Decision to Use the Atomic Bomb,” The Asia Pacific Journal, Vol. 14-2-09, April 4, 2009.

Alex Wellerstein, "The Kyoto misconception," http://blog.nuclearsecrecy.com/2014/08/08/kyoto-misconception/

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    You might want to try to explain why there is a difference between using atomic bombs on Hiroshima & Nagasaki, and using conventional bombs on Tokyo. More people were killed in the latter: en.wikipedia.org/wiki/Bombing_of_Tokyo
    – jamesqf
    Feb 2, 2019 at 4:04
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    @jamesqf: I'm not clear on why you think that's relevant. The question is about what Truman knew about the targeting of the nuclear bombs.
    – user2848
    Feb 3, 2019 at 2:57
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    It's relevant because the OP appears to be implying that had Truman (or other people in the decision chain) known that Hiroshima was not a purely military target, they would not have ordered the bomb to be dropped on it. But the plain fact of the matter is that civilian targets were attacked throughout the war, by all parties.
    – jamesqf
    Feb 3, 2019 at 4:51
  • Although torpedoed on July 30, the navy only "learned of the sinking when survivors were spotted four days later [Aug. 3] by the crew of a PV-1 Ventura on routine patrol." That is five days (subject to timezone/international-date-line adjustments) following the targeting decision by Truman. You have also made several specious, and possibly defamatory, claims about principals involved in the decision without providing any supporting evidence.. Feb 3, 2019 at 22:02
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    It may be pointed out that Hiroshima was difficult to destroy using conventional bombs (due to it's spread) and fire bombs (as it has rivers creating fire barriers).
    – liftarn
    Feb 4, 2019 at 10:10

I think you may not be properly evaluating the context of the diary entry you provide:

I have told [Stimson] to use [the first nuclear bomb] so that military objectives and soldiers and sailors are the target and not women and children. Even if the Japs are savages, ruthless, merciless and fanatic, we as the leader of the world for the common welfare cannot drop this terrible bomb on the old Capitol or the new.

He & I are in accord. The target will be a purely military one and we will issue a warning statement asking the Japs to surrender and save lives.

You are taking this to mean that Truman believed that Hiroshima was a military base and not a city with civilian inhabitants. That is not the meaning I take from it at all.

Kyoto was considered as a target, and Kyoto's military and industrial value was negligible. Kyoto's value was primarily cultural, historical, and psychological. Destroying Kyoto would have been an attempt to break the Japanese politically through sheer terrorization, with very little direct military benefit at all.

The sense I get from this diary entry is that Hiroshima, compared to Kyoto, was a traditional military target.

One could make an analogy to a hypothetical war against (for example) Saudi Arabia. If one launched a nuclear weapon against Saudi Arabia, one would have to choose between traditional targets with military value, and Mecca. Mecca would be a psychological target and not a military one. If Mecca was up for consideration as a target and you rejected it as a target, you might then write in your diary "We chose to go with a military target instead" even if the target you chose had a large civilian population.

  • I'm sorry I DEved. Kyoto was considered one of the best 2 targets until the end. Kyoto was also considered a military and industrial city by a document, dated on 12 May, 1945
    – user12387
    Feb 21, 2019 at 17:16
  • @Kentaro Tomono, I completely understand your position. To me it's less a matter of whether there was a planning document somewhere describing Kyoto as a military target, and more a matter of what Truman - as a somewhat provincial Midwestern American of the 1940's - would have thought. And to the extent such an American would have had a mental image of Kyoto at all, it would have been of the Kyoto of The Tale of Genji. Hiroshima would have just been a name on the map at that point.
    – tbrookside
    Feb 21, 2019 at 18:49
  • I have no 100% idea what you are talking about. It was a war time. Truman and other high rankings in profiles wouldn't have been dreaming Kyoto as Kyoto Today as it would be in your mind.
    – user12387
    Feb 21, 2019 at 21:08
  • @KentaroTomono If you are referring to the Minutes of the second meeting of the Target Committee, dated 12 May 1945, it does not describe Kyoto as a military target. However, you are right that Kyoto and Hiroshima were both designated AA targets at that meeting, but unlike Kyoto, Hiroshima was described as an important army depot and port of embarkation. Given that distinction and the quote provided here, this answer seems a reasonable interpretation of the evidence. Feb 21, 2019 at 23:05
  • @sempaiscuba Yes, that's the material I refer to. Sorry for that and to tbrookside.
    – user12387
    Feb 22, 2019 at 16:32

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