Why Bomb Hiroshima and Nagasaki?

Why didn’t the US drop an A-bomb or H-bomb nearer to Tokyo itself? Didn’t we take a calculated risk that the Japanese might not surrender? How many working bombs did we have at the time?

If we were really trying to end the war as quickly as possible why pick two industrial but non governmental cities? Or was it to spare innocent lives?

Part of the reason was so that they wouldn’t kill all of the men whom they were trying to get to surrender.

I seem to remember that cities with an historical signifiance were excluded from the list of potential targets. Might have been the case for Tokyo.

The USA had only the two bombs that were actually used. Producing others would have taken several months, if the first ones had not caused Japan to surrender.

Tokyo had already been pretty much eradicated by conventional bombing on February 23/24, March 9/10 and May 26, 1945. The atomic bombs were dropped August 6th and 9th. Roughly the same number of people. albeit all civilians, died in the Tokyo firebombings as at Nagasaki and Hiroshima combined.

Bombing Tokyo would only show our ability to make rubble bounce. There were a number of cities that were big enough to be significant but which had previously not been subjected to the devastation that conventional and firebombing that Tokyo (or the other really important cities) had.

Taking a more or less pristine city and laying waste to it more starkly demonstrated the Americans’ powerful new weapon. One plane. One bomb. One city.

IIRC, part of the reason was that, being relatively far from most US air bases (before Okinawa was taken), Hiroshima and Nagasaki had mostly avoided heavy bombing up until that time.

Some good primary source material here, including Truman’s diary and the order itself. Hiroshima was first and Nagasaki third on the list of cities; Kokura was second. Truman considered Hiroshima “a military base” and a valid target; he actually said he wanted to minimize the number of civilians killed.

Sorry, submitted too fast: The Wikipedia article on the bombings is a good objective overview.

We also needed to see the complete effects of the blast, so that we could refine the weapon later. That could only be accomplished by nuking a previously unrubbled city.

Our primary rationale for choosing Hiroshima was that it was nominally a “military target” because it housed the Imperial Army Headquarters for western Japan, it was relatively undestroyed (not even close to pristine, though… USAAF estimated listed it at 40% destroyed prior to August), and it was large enough for the full effects of the bomb to be felt. Tokyo was considered (as was dropping the bomb on the Imperial palace) but dismissed as a target because it had largely been destroyed and would be difficult to justify as a military target. Also, destroying the top of the Japanese government could have thrown the nation into chaos.

Nagasaki was not designated as a primary target for the bomb. The intended second target was the city of Kokura (modern Kitakyushu), the location of the Kokura Arsenal, one of Japan’s centers for weapon and munition production. Kokura was covered with heavy clouds so the B-29 moved on to Nagasaki (which was really a pretty insignificant city).

Two. There had been one other one and that had been used as a test bomb at the Trinity site. If the Japanese hadn’t surrendered it would have been several months before more bombs were available.

Nagasaki was also an industrial city, albeit a relatively small one. One comparison I read was that Nagasaki was the equivalent of Toledo, Ohio or Gary, Indiana.

The USAAF compared Nagasaki to Akron, Ohio in their report. Nagasaki was involved with shipbuilding, but it’s designation as a secondary target had more to do with it’s location on the way back from Kokura than any inherent value as a target.

No H-Bomb (hydrogen fussion) was ever used in (hot) war, they both were A-bombs.

There were actually all the components for another Fat Man device en route to Tinian at the time of the Nagasaki bombing. (For each of the bombs, pieces were shipped seperately and then these were assembled on the island just prior to use.) Had there been no surrender - or the stop order from Truman just before that - it was the intention to use that against another city immediately it was available.
Partly because they were running out of suitable cities to target and partly to stockpile a couple or so of them for use against the beaches in any invasion that autumn, at that point they’d have stopped. Offhand, the intended production rate was about one plutonium bomb a month through to the end of the year, though as it turned out in peacetime this wasn’t acheived.

Do you have a cite for that? From what I’ve read there were three atomic bombs available in 1945; the Trinity test bomb, and the Hiroshima and Nagasaki bombs.

If today’s Pentagon said they had three super weapons, don’t you figure they’d have at least four? :slight_smile:


The components weren’t actually en route at the time of Nagasaki - my memory of the schedule was a few days out - but they were being readied to be flown to Tinian and George C. Marschall was told by Groves on the 10th, the day after Nagasaki, that he expected the next bombing to be on the 17th or 18th.
Groves’s basis for this estimate was a telegram from Oppenheimer the day before (i.e. the 9th) stating when the components would leave Los Alamos for Kirtland and thence to Tinian. The high explosive lenses would leave on the morning of the 11th and the plutonium core would leave on the evening of the 12th. There was already a stockpile of the other components, like the casing, on Tinian.
The timing of the two previous attacks had been left to the military, but events were beginning to move rather fast by this stage. Truman removed that existing freedom on the 10th, allowing the military to continue with preparations for another bombing but requiring that the use of this next weapon depend on his explicit approval. Probably independently, Groves and Oppenheimer agreed to proceed cautiously when it came to shipping stuff. Robert Bacher, who had become Los Alamos’s specialist in handling completed plutonium cores, apparently had this core in the car ready to be driven to Kirtland when Groves cancelled the transfer.

Groves’s estimate to Marshall is quoted in Racing for the Bomb (Steerforth, 2002, p424) by Robert Norris and the exchanges with Oppenheimer are summarised in Critical Assembly (Cambridge, 1993) by Hoddeson et al.

Besides, the H-bomb wasn’t even developed until 1952. Maybe the US would have been able to develop something along the lines of Ivy Mike sooner, though I bet that had the war with Japan even dragged on long enough to give time to collect enough uranium and plutonium to build more bombs, they probably wouldn’t have even tried boosting the yield with tritium. And we are talking about several months here, which would have more firebombing and an eventual full-scale invasion of the home islands during the time more bombs were being constructed. Better to make designs that you know will work than start messing around with new ones which could have the same development time as the Manhattan Project–after all, the hydrogen bomb was not easy to design to get the fusion reaction.

That is true. As an aside, the ancient capital of Japan was Kyoto, at the time a city of around one million people. Some people, Stanton being one, were able to convince FDR and the military powers that be, that Kyoto should be spared. It was the cultural and artistic center of Japan (some 1,000 shrines and temples) and no military facilities to speak of. It is one of the great and beautiful cities of the world. It was spared.

However, because it was big, surrounded by mountains, and untouched by any bombing at all, at one time it was being considered for the first A-bomb. Fortunately, it was eliminated as a target.

It is especially lucky for me, because my wife lived there and was still in school during the war. Because of the physical setup and the type of houses, it is doubtful whether much of anybody would have survived.

I was fortunate enough to live there for two years during the Korean War, and even though things were tough only four years after WWII, it was a wonderful place in which to live.

My wife remembers huge flights of B-29s flying over to bomb Osaka, about 20 miles away. She was indeed, lucky.

That was an eloquent post, so don’t take the following as a nitpick.

The sparing of Kyoto was almost entirely due to the US Secretary of War, Henry Stimson. It’s a story that’s virtually invariably told in terms of him vetoing the city from the target list presented to him, on the grounds that he’d visited it (twice, in fact) and knew it to be a cultural jewel. That’s true as far as it goes. What is very rarely recognised is that Stimson had to fight to get this decision to stick. For Leslie Groves, the head of the Manhattan project, was having none of this. Like the experienced administrator and expert manipulator of bureaucratic systems that Groves undoubtedly was, he realised that the best way to get round Stimson’s veto was simply to pretend it wasn’t there and so he kept adding Kyoto back to the list. (With the rational that a Japanese city of a million people had to be of significance to their war effort.) And Stimson kept scoring it off. Only for Groves to slip it back on. The whole process went on for weeks, back and forth.
Eventually, Stimson bumped it up to Truman while they were at Potsdam. In what he probably took as a minor call, he agreed and Stimson prevailed. Kyoto was spared. The next on the list, Hiroshima, wasn’t.