# Why did Japan think attacking Pearl Harbor was a good idea? **URL:** \ **Category:** Great Debates\ **Created:** [May 29, 2018, 9:03pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089 "2018-05-29T21:03:36Z")\ **Posts on this page:** 16\ **Page:** 8
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [June 4, 2018, 2:24pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/141 "2018-06-04T14:24:36Z")
The force a fluid exerts on a wall is 1/2(ro_G_h). As the height h increases, they might need a thicker wall. Those are rather tall. ---
**Author:** ![Mr.Miskatonic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mr.miskatonic/32/310_2.png) [@Mr.Miskatonic](https://boards.straightdope.com/u/Mr.Miskatonic)\ **Post date:** [June 4, 2018, 2:55pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/142 "2018-06-04T14:55:06Z")
> [@Corry\_El](#): > > I can’t 100% vouch for that document. Oh, I don’t doubt its authenticity. It looks like it was earlier oil storage tanks located elsewhere that might have either held some other fuel or were was all that was needed for PH when a large portion of the fleet still ran on coal. > [@](#): > > The guy who posted it is as I referred to, just IMO, a little carred away sometimes in his scenario’s of greater Japanese success in the PH operation, including invasion, heavy ship bombardment and so forth. He tends to emphasize facts in favor of his arguments and de-emphasize those against it more than average IMO, though most of us do that sometimes to some degree I think. But I never caught him trying to put forward outright bogus info. I doubt that’s the case. Sounds like the guys borders a bit on what we call Tojoboo. 🙂 > [@](#): > > Also (I have a degree in naval architecture, not a shore side oil tank designer) I don’t understand why such a tank would be as thick as 1.5" in particular. Even a large modern tanker’s shell plating isn’t that thick anywhere. The parts in the relatively low stress areas toward the middle (from bottom to main deck) are typically around 1/2". The upper and lower side shell plating and deck and bottom are thicker (though not 1.5") to counter the stress of waves as the tanker’s hull acts like a big girder, wave crests and troughs spaced a few 100’ apart. Where the structure only has to resist the hydrostatic pressure of the water outside pushing in (and it has to do so assuming no liquid inside pushing back) 1/2" is plenty. Something like 1/2" for WWII era or earlier shore oil tanks is what I would have guessed, especially nearer the top where the hydrostatic pressure is less. Which isn’t to say there are no thicker shore oil tanks, just that that document gives a plausible description IMO. Fair enough, and without having access to Zimm’s discussions with his experts I cannot comment any further, especially since I was poorly recalling a lot of Zimm’s position (I read it not long after it came out) in any case. I wasn’t flat wrong, its just Zimm’s point was not about steel thickness but rather than the tanks weren’t as vulnerable as folks make it out to me, nor was the oil irreplaceable. BTW, do you have a source on that API ammo in the downed Zero? I was under the impression that the IJN pilots didn’t really bother with thinking the machine guns on their planes for much more than soft targets, given what was written about their usefulness against US planes in _Shattered Sword_. ---
**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\ **Post date:** [June 4, 2018, 3:21pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/143 "2018-06-04T15:21:26Z")
> [@Mr.Miskatonic](#): > > BTW, do you have a source on that API ammo in the downed Zero? I was under the impression that the IJN pilots didn’t really bother with thinking the machine guns on their planes for much more than soft targets, given what was written about their usefulness against US planes in _Shattered Sword_. Separate Ball (ie copper jacketed aluminum/lead cored), AP (ie steel cored) and incendiary rounds, put into the ammo belts in threes. The source for that being the load out on the Akutan Zero is “Koga’s Zero: The Fighter that Changed WWII” by Jim Rearden. Background on the types of ammo used by the Type 97 aircraft machine gun can be found on the Japanese language Wiki page on .303 ammo. All three of those types definitely existed. > **[.303ブリティッシュ弾](https://ja.wikipedia.org/wiki/.303%E3%83%96%E3%83%AA%E3%83%86%E3%82%A3%E3%83%83%E3%82%B7%E3%83%A5%E5%BC%BE)** > > .303ブリティッシュ弾（303ブリティッシュだん）または7.7×56mmRないし7.7x56Rmmは、最初は1888年にリー・メトフォード小銃用の黒色火薬を使用する実包として、次にリー・エンフィールド小銃用の無煙火薬を使用する実包として、イギリスで開発された、.311インチ口径のライフル、カービン、機関銃用の実包である。 > 1950年代まで、イギリスとイギリス連邦の標準軍用実包であった。 > .303インチ（7.7mm）は、より古い黒色火薬時代の用語体系に従った、ライフリングの山の頂点間で測定された口径の公称寸法である。ライフリングの谷の間で測定された公称寸法は.311インチ（7.9mm）である。多くの.303インチ軍放出ライフルでは、口径がしばしば.309インチ（7.8mm）から.318インチ（8.1mm）までに及ぶのが見られる。標準の.303実包のために推奨されている弾丸直径は.312インチ（7.92mm）である。 > この実包は軍放出ライフルと共に、特にオーストラリア、カナダ、ニュージーランド、またある程度はアメリカ合衆国と南アフリカでも、狩猟用途に多用された。カナダでは、それが大型... The typically ~3/8" seat armor on US fighters of that time could stop the 7.7mm AP round. Besides being armor plate not mild steel\*, such a round had to penetrate the plane’s aluminum skin at a generally very acute angle then probably cut through some internal aluminum structure after that before hitting the seat armor. Note that while US .50 API has been mentioned, that type of round wasn’t actually used at the time of PH either. At that time similarly US fighters used mixes of AP and incendiary in their ammo belts. The API round became common from ca. 1943. Still, even non AP .50 rounds would easily go through 1/2" of mild steel, so if the person’s off the cuff reference was US capabilities, and not considering that Japanese a/c mg’s were smaller caliber (then, later model Zeroes used a copy of the .50 Browning besides longer barreled 20mm) they might view 1/2" of mild steel as quite vulnerable to ‘a/c machine guns’. \*in a few cases in the early months of the war USN F4F-3 fighters were fitted ad hoc with mild steel ie ‘boiler plate’ behind the pilot’s seat. There’s not enough data AFAIK to know if that actually would have stopped 7.7mm AP. Later on, kits with real armor were issued, then F4F-4’s were fitted with armor at the factory. Likewise F4F-3’s didn’t have self sealing fuel tanks at the beginning, crude liners retrofitted in some not all early actions, but the USN fighters at Midway were F4F-4’s with tank liners as well as seat armor fitted at the factory. ---
**Author:** ![Mr.Miskatonic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mr.miskatonic/32/310_2.png) [@Mr.Miskatonic](https://boards.straightdope.com/u/Mr.Miskatonic)\ **Post date:** [June 4, 2018, 3:32pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/144 "2018-06-04T15:32:58Z")
> [@TokyoBayer](#): > > The US embargoed oil, starting a countdown in which Japan would either have to accept what it considered impossible demands or go to war. Many leaders believed that accepting the demands would be the equivalent of losing a war, so why not go out fighting. Interestingly, some have noted that the re-arming of the US was drastically cutting into the US exports of oil as it was needed domestically for all the new military gear. So much so that the embargo was almost an empty gesture. Mind you, had production increased or re-arming died down that would mean some of the oil was exportable again and the embargo would matter. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [June 4, 2018, 6:37pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/145 "2018-06-04T18:37:33Z")
> [@TokyoBayer](#): > > The US embargoed oil, starting a countdown in which Japan would either have to accept what it considered impossible demands or go to war. Many leaders believed that accepting the demands would be the equivalent of losing a war, so why not go out fighting. > > Because of the status given to the decision of the Imperial Conference, it became difficult for leaders to fight against the incremental steps towards war. Although they attempted to negotiated with the US, what they offered the US and what the US wanted were far enough apart that a negotiated settlement wasn’t really possible. > . Good summation- one thing I need to stress is that only Japan sees it as America forcing them to go to war. Everyone sees it as Japan not stopping it’s military absorption of other nations and areas. One thing I read, which may or may not be true, is that the USA demanded Japan withdraw from China, but we didn’t consider Manchuria part of China. Still basically the USA demanded that Japan withdraw from conquered areas or they wouldnt sell Oil, etc to Japan. Outside of Manchuria , the Japanese army was having a real hard time of it anyway. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [June 5, 2018, 12:15am UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/146 "2018-06-05T00:15:43Z")
> [@Jackmannii](#): > > From numerous accounts I’ve read, hardly any Japanese leaders recognized that “time was running out” before the attack on Pearl Harbor (Yamamoto may have been the only major military figure who realized that the war had to be won in one overwhelming battle before a war of attrition set in, and even he wasn’t optimistic about the outcome). > > Most pooh-poohed the idea that U.S. economic/military strength could become a significant factor because of the allegedly superior Japanese fighting spirit, and that opposition would crumble after the elusive “decisive” Japanese victory. Please see my recent post. The time was indeed running out, but more specifically because of oil. The Japanese navy had a two-year supply of _peacetime_ oil reserves. They needed to obtain more (either by war or agreeing to what they felt was unacceptable terms). While some Japanese leaders believed that they could defeat everyone and all, others were not so sure. Tojo Hideki was one of the those would was worried about the Western powers. He was worried about the growing ABCD (American, British, Chinese and Dutch) powers becoming stronger and strangling Japan. However, when informed exactly how strong the US was becoming, he disregarded that with the Japanese fighting spirit argument. The US and Japan had agreed that the Pacific mandates for both countries would not be fortified. Japan had withdrawn from the League of Nations but didn’t return the mandates (gosh, wonder why) and had fortified them. The US was beginning to in 1941. The US believed that a war was coming, but thought that they had until spring of 1942. > [@John\_DiFool](#): > > War Plan Orange in its original formulation was well-known by the Japanese. The question is whether the high-Navy brass would have read the writing on the wall and altered their plans (as they historically did), played a patient waiting game, vs. charging out of Pearl hell-bent towards the Philippines and their doom. They would have had the loss of the British Force Z as a cautionary tale, note. According to Zimm’s book, the US had already made that change in strategy to wait until they had built up further forces. IIRC, the Orange War plan called for waiting for a six months(?) to move aggressively. In the meanwhile, the US was building up forces and fortifications in the Pacific. Interestingly, while the US rethought the idea of battleship supremacy after Pearl Harbor, the Japanese really didn’t get it. > [@DrDeth](#): > > Except, of course with that Two Ocean navy, about half was on the Atlantic side, and the Japanese did know that Roosevelt wanted to get into a war with Japan. So- _maybe_- they only had to deal with half the US Navy. I don’t know if that would be a valid assumption for future growth, which Japan would be very well aware that the US would not need as large of a navy in the Atlantic. ---
**Author:** ![Malthus](https://avatars.discourse-cdn.com/v4/letter/m/85f322/32.png) [@Malthus](https://boards.straightdope.com/u/Malthus)\ **Post date:** [June 5, 2018, 1:26pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/147 "2018-06-05T13:26:12Z")
Also a factor was just how messed up Japan’s governmental system was at the time – with assassination of government ministers seen as being insufficiently militant being a fact of life for years leading up to the war, the army and navy acting like independent governments (and not at all friendly towards each other), etc. It is entirely possible that making a rational decision on a risk/benefit basis was simply not an option for them; how possible was it for any in the Japanese leadership to tell the army to stop attacking China, if that was the price of avoiding a crippling embargo? ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [June 5, 2018, 1:33pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/148 "2018-06-05T13:33:18Z")
> [@Mr.Miskatonic](#): > > Interestingly, some have noted that the re-arming of the US was drastically cutting into the US exports of oil as it was needed domestically for all the new military gear. So much so that the embargo was almost an empty gesture. > > Mind you, had production increased or re-arming died down that would mean some of the oil was exportable again and the embargo would matter. I have not been able to google anything to support this argument. At the time of the embargo, the US was supplying 60 to 80% of Japanese needs (depending on the sources). I haven’t found anything which said that the exports had already dwindled down to zero. I did [find this](http://pwencycl.kgbudge.com/O/i/Oil.htm) > [@](#): > > California produced about 15% of U.S. oil, some 203 million barrels per year, but actual pumping capacity in 1941 was 1.37 billion barrels per year. Refinery capacity was about 296 million barrels per year. The Los Angeles basin tended to produce medium to heavy crude oil suitable for refining into fuel oil for ships, while fields in the San Joaquin Valley tended to produce lighter crude oil rich in gasoline. Because there was no pipeline connection from California to the eastern United States in 1941, and transport by rail or by tanker through the Panama Canal was uneconomical, California production was consumed almost entirely around the Pacific Rim. The Dutch and British had joined with the US in the embargo, so Japan was cut off from the other sources. They had been importing a significant amount from the DEI, although talks concerning importing more had broken down. Cordell Hull, Secretary of State and Frank Knotts, Secretary of the Navy (a cabinet position) were opposed to the sanctions as they believed it was tantamount to declaring war. Several sources claim that Roosevelt had not intended the oil embargo to be 100% and that the Japanese could apply for special permits for importing a certain amount of oil, but that the American leaders who were in charge of oil dispersement refused to allow the Japanese to obtain any. In addition, the embargo also included other raw material required for Japanese industrial purposes as well and their war efforts. As an aside, in her book, Eri Hotta discusses growing problems which were caused by reduced supplies to civilians, such as the disposal of night soil from Tokyo. Prior to civilian rationing because of the war in China, this had been done by truck. > [@DrDeth](#): > > Good summation- one thing I need to stress is that only Japan sees it as America forcing them to go to war. Everyone sees it as Japan not stopping it’s military absorption of other nations and areas. I assumed that all or almost all the readers here would be familiar with that. I’m also assuming the people will not presume my familiarity with the Japanese side involves any sympathy for their actions. > [@](#): > > One thing I read, which may or may not be true, is that the USA demanded Japan withdraw from China, but we didn’t consider Manchuria part of China. It was not that simple. Japanese negotiators were handicapped by the position of their government which was in chaos, with no clear overall leadership. They wanted an unacceptable amount of time to withdraw from China, even if there could obtain a consensus to agree to a withdraw. Again, without a clear leader opposed to the war, things just muddled along. It could also very well have been that even had the US agreed to resume oil shipments, there were enough voices calling for war that the negotiations would have failed by the November 1st deadline which the Japanese had secretly set as the make or bread date. Now back to other things. Both sides made a number of critical mistakes in their assumptions about the other side. Japan’s most obvious one was assuming that the US could quickly settle. Many leaders in the US were assuming that Japan would never attempt a war against the US, and consequently thought the measure such as oil embargo would not lead to war. Japan assumed that their fighting spirit would prevail, and far too many Americans assumed that the Japanese could not fight effectively. The [same cite](http://pwencycl.kgbudge.com/O/i/Oil.htm) claims this. I have no way to vouch for its accuracy, but it’s an interesting tidbit. > [@](#): > > Unlike gasoline, fuel oil is not easily ignited and fuel oil tanks were not as easy a target to destroy as might be supposed. One Japanese pilot who participated in the raid on Wheeler Field recalled strafing some nearby fuel tanks and being surprised that they refused to ignite even after several strafing runs. I’m not going to get involved in that debate, but an interesting point is that it illustrates the difference in the mindsets of the two sides. As I posted earlier, one Japanese officer said that they didn’t attack the oil tanks because they weren’t thinking of US logistics. Had they been thinking of US logistics, they they would have thought more about their own logistics. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [June 5, 2018, 3:49pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/149 "2018-06-05T15:49:50Z")
> [@Malthus](#): > > It is entirely possible that making a rational decision on a risk/benefit basis was simply not an option for them; how possible was it for any in the Japanese leadership to tell the army to stop attacking China, if that was the price of avoiding a crippling embargo? The Japanese leadership _was_ the Army. The Diet was pretty irrelevant by then. ---
**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\ **Post date:** [June 5, 2018, 7:19pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/150 "2018-06-05T19:19:30Z")
> [@Mr.Miskatonic](#): > > Interestingly, some have noted that the re-arming of the US was drastically cutting into the US exports of oil as it was needed domestically for all the new military gear. So much so that the embargo was almost an empty gesture. In “Bankrupting the Enemy” Miller shows graphs of Japanese oil imports from the US by year. The annualized rate in the months of 1941 pre-embargo dropped around 30% from the 1939 volume (1940 was in between) to around the level prevailing in the mid 1930’s. So it did decline just before the embargo but not enough to make the embargo nearly an empty gesture, even temporarily. And it was attributed in part to soft sanctions. The US didn’t say it was refusing to export all oil to Japan till mid 1941 (except \>=87 octane gasoline exports banned in mid 1940), but export licenses had to be granted and they were increasingly slow walked especially for crude particularly suitable for gasoline production, and for gasoline near the octane limit of the 1940 ban. Although in the total picture sure, a faster growing US economy cushioned the blow for CA oil producers from creeping restrictions then outright Japan export ban by boosting oil demand elsewhere in the US. US real GDP grew 17.7% in 1941, final general recovery from the Depression in part from rearmament. As Pac War encyclopedia points out there were no oil pipelines to the US West Coast then (one Canadian pipeline has a terminal in Anacortes WA now, otherwise there still aren’t). But shipping oil to rest of US via the Panama Canal wasn’t prohibitive. It happened then and it’s not unheard of even now (other direction usually). ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [June 6, 2018, 2:43am UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/151 "2018-06-06T02:43:37Z")
The Trans Mountain pipeline, built in the early 50s, terminates on the BC coast, doesn’t it? ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [June 6, 2018, 4:06am UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/152 "2018-06-06T04:06:28Z")
> [@Little\_Nemo](#): > > I enjoy discussing historical issues. I don’t enjoy arguing. So when I feel things are reaching the point of being an argument, I just stop responding. > > I’ll admit I have difficulty with this sometimes. I’m human and I fall into the [“someone is wrong on the internet”](https://xkcd.com/386/) trap. But I’m trying to work on this and develop the attitude that it’s not my responsibility to change minds. I tell myself that I’ve said what I wanted to say on a subject; if people want to read what I think, it’s there. If they don’t want to read what I think, writing it several more times won’t change that. What do you call it when you make a statement which is obviously wrong, then when challenged you retreat because you don’t like “arguing?” Where did you get that idea that the Japanese believed that the US would not achieve parity until 1950? Here is yet [another cite](https://ssi.armywarcollege.edu/pdffiles/pub905.pdf) (from the US Army War College) which says your statement is completely rubbish: > [@](#): > > The first assumption was that time was working against Japan—i.e., the longer Japan waited to initiate war against the United States, the dimmer its prospects for success. This assumption was grimly realistic. As the embargo took hold and the United States accelerated its rearmament, Japan’s economic and military power vis-à-vis that of the United States began to rapidly decline. In the critical category of naval tonnage, Japan in late 1941 possessed a competitive 70 percent of total U.S. naval tonnage (including tonnage employed in the Atlantic), but the Japanese correctly projected, based on existing naval building programs (and excluding estimated losses), that the ratio would drop to 65 percent in 1942, 50 percent in 1943, and 30 percent in 1944. The Two-Ocean Navy Act passed by Congress in July 1940 called for a 70 percent increase in U.S. naval tonnage, including construction of 18 aircraft carriers, 6 battleships, 33 cruisers, 115 destroyers, and 43 submarines. You seem to believe that a debate is simply repeating yourself again and again, even in the face of authoritarian cites. This is the Dope. You can’t get away with that. ---
**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\ **Post date:** [June 6, 2018, 1:57pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/153 "2018-06-06T13:57:45Z")
> [@Northern\_Piper](#): > > The Trans Mountain pipeline, built in the early 50s, terminates on the BC coast, doesn’t it? My statement for review: “As Pac War encyclopedia points out there were no oil pipelines to the US West Coast then (one Canadian pipeline has a terminal in Anacortes WA now, otherwise there still aren’t).” I believe it’s correct. The Trans Mountain has one terminal in Anacortes, WA and another in Burnaby, BC after going across western Canada from Edmonton. But other than that one Canadian pipeline with a US terminal, there are no oil pipelines to the US West Coast. ---
**Author:** ![TokyoBayer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tokyobayer/32/13989_2.png) [@TokyoBayer](https://boards.straightdope.com/u/TokyoBayer)\ **Post date:** [June 7, 2018, 1:55pm UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/154 "2018-06-07T13:55:46Z")
> [@Johnny\_Bravo](#): > > I’m actually reading through a book right now that mentions an interesting tidbit: > > After FDR approved the draft but before Pearl Harbor, a lot of polling was happening to gauge public sentiment about going to war. Apparently at least one poll on the West Coast showed that folks out there were pretty ambivalent about Germany but were much more open to the prospect of war with Japan. Here’s the [1941 Gallup polls](http://ibiblio.org/pha/Gallup/Gallup%201941.htm) concerning war, including this: > [@](#): > > SEPTEMBER 7 > > JAPAN > > Interviewing Date 8/21-26/41 > > Survey #245-K Question #13 > > Should the United States take steps now to keep Japan from becoming more powerful, even if it means risking a war with Japan? > > Yes… 70% > No… 18 > No opinion… 12 > > By Region > > New England and Middle Atlantic > Yes… 72% > No… 19 > No opinion… 9 > > East Central > Yes… 61% > No… 24 > No opinion… 15 > > West Central > Yes… 64% > No… 21 > No opinion… 15 > > South > Yes… 76% > No… 11 > No opinion… 13 Polls much earlier in the year showed that opinion was split on risking war with Japan to save the DEI and Singapore. > [@](#): > > MARCH 14 JAPAN > > Interviewing Date 2/16-21/41 > > Survey #230-T Question #7a > > Do you think the United States should risk war with Japan, if necessary, to keep Japan from taking the Dutch East Indies and Singapore? > > Yes…40% > No… 39 > No opinion…21 There does seem to be much more support for a possible war against Japan than against Germany. There could be racial reasons for this, but also I suspect most people did not believe a war with Japan would be as costly – in terms of lives as well as material – as what it turned out to be. ---
**Author:** ![Mr.Miskatonic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mr.miskatonic/32/310_2.png) [@Mr.Miskatonic](https://boards.straightdope.com/u/Mr.Miskatonic)\ **Post date:** [June 8, 2018, 12:45am UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/155 "2018-06-08T00:45:20Z")
> [@TokyoBayer](#): > > Here’s the [1941 Gallup polls](http://ibiblio.org/pha/Gallup/Gallup%201941.htm) concerning war, including this:Polls much earlier in the year showed that opinion was split on risking war with Japan to save the DEI and Singapore.There does seem to be much more support for a possible war against Japan than against Germany. There could be racial reasons for this, but also I suspect most people did not believe a war with Japan would be as costly – in terms of lives as well as material – as what it turned out to be. I suspect it may two parts to the answer 1. oh boy…getting involved in another Continental European war…hooray… 2. Japan did actually threaten our positions in The Pacific, unlike Germany which could do little more that use U-boats against us. But yeah, I’d say there was an element of thinking Japan would be a pushover compared to Germany was a factor as well. ---
**Author:** ![KellyCriterion](https://avatars.discourse-cdn.com/v4/letter/k/b3f665/32.png) [@KellyCriterion](https://boards.straightdope.com/u/KellyCriterion)\ **Post date:** [June 8, 2018, 6:43am UTC](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089/156 "2018-06-08T06:43:30Z")
One thing that barely gets mentioned in discussions on why Japan attacked Pearl Harbour in 1941, is that 90 years earlier, the United States Navy showed up with gunships in the port of Edo, Japan making various demands to the Japanese around trade, port access for American ships, etc. When the Japanese side stalled the negotiations, the American fleet commander (Captain Perry) threatened the Japanese with war. History records that the Japanese agreed to the demands only under duress, when they realised they wouldn’t be able to defend themselves against an American attack. I think this incident is very relevant when trying to understand the Japanese psyche in 1941. (Wikipedia has an excellent article about the [Perry Expedition](https://en.wikipedia.org/wiki/Perry_Expedition)). [Previous page](https://boards.straightdope.com/t/why-did-japan-think-attacking-pearl-harbor-was-a-good-idea/815089.md?page=7)