# Question regarding the attack on Pearl Harbor **URL:** \ **Category:** Factual Questions\ **Created:** [August 19, 2013, 10:26am UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628 "2013-08-19T10:26:03Z")\ **Posts on this page:** 20\ **Page:** 5
**Author:** ![Dissonance](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@Dissonance](https://boards.straightdope.com/u/Dissonance)\ **Post date:** [August 26, 2013, 9:22am UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/81 "2013-08-26T09:22:57Z")
> [@Bremidon](#): > > 1. Several people have strawmanned what I said, but you actually took on what I said head on: that it is plausible that in the first day after the attacks that the military and political leadership swung from underestimating the Japanese to overestimating them. Thanks for actually responding to what I said and not what would have been easier to counter. That isn’t what **Martin Hyde** said in context to the idea that anyone thought Japan was going to land in the mainland US, and no one has straw manned what you said. As someone said, a politician or two may have panicked, but the idea that any of the military leadership or high level political leadership took the threat of a Japanese invasion of the mainland seriously is absurd, much less the idea that the Army was drawing up plans to fall back to Chicago. As noted, there were plenty of troops in California and Washington state alone, and far more throughout the states. This notion that the Japanese Army outnumbered the US Army by 20 to 1 is entirely false. That would mean the size of the IJA was over 30 million men. The US Army had a strength of [1,657,157](http://www.historyshots.com/usarmy/backstory.cfm) on Dec 31, 1941. Japan was logistically incapable of invading the mainland US, and even if it were, the idea that the Army was planning to abandon half of the continent without a fight is utterly rediculous. > [@](#): > > 1. I am not a WWII scholar, I do not claim to be, and I doubt I ever will be. I have, however, spent the last 20 years in Germany, so I’ve maybe picked up on a few different viewpoints that some of the posters on these boards might find interesting. This does not make me an expert, but I thought I would throw out something that those of you in the States might not have heard before. Tuns out I am right about that, at least. Again, sadly not really. The quality of ‘documentaries’ on the Hitler, I mean History channel is piss poor. > [@](#): > > 1. ie. Japanese soldiers in Asia: yes, we now know what strategy the Japanese followed, and in that respect it was fairly predictable as it turns out. What I am curious about is: were those soldiers pinned down in Asia, or could have Japan decided to blow China for the moment and gone full bore after the States to convince them to drop the embargo? Considering that Japan was often able to use local authorities to do their dirty work for them, would they have been able to risk quietly pulling out most of their troops? And yeah, I know next to nothing about the Japanese/Chinese side of things other than the main headlines which is why I’m asking. Not a chance in hell. The entire reason for the oil embargo was to force Japan to quit China, and the reason for the attack on the DEI was to sieze a new source of oil by force. There is no way Japan could “quietly” remove most of their troops from China, and no point in doing so anyway. Without the transports to move them or the shipping to logistically support them, what use would they have been? “Going full bore after the States” was something they simply were incapable of in any way you are imagining it, going full bore would mean possibly trying to land a platoon or two by submarine. Even if there were a plausible option to try invading the US, the only way they were going to convince the US to lift the oil embargo would to be to physically sieze the oil fields in Texas. Why on earth would they consider doing that when the oil in the Dutch East Indies was much, much closer, and didn’t require launching an invasion across the entire Pacific Ocean and then conquering half of a continent before even reaching the oil fields? > [@](#): > > 1. Secret buildup of transports. This is argument you make that is most convincing to me. Could Japan have possibly held such a large project secret? Doubtful, maybe even implausible, but certainly not impossible. In a cold analysis, I would agree with you 100%. Would I have agreed in December, 1941? I’m not sure. Give me time to think about this and see if I can come up with anything else to add any strength to this idea. Japan was short on shipping as it was in 1941. With the loss of access to the use of other nation’s shipping by going to war, even with the seizing of such foreign vessels as they could Japan only had 6 million tons of merchant shipping. This was barely enough to support troop movements, troops and bases over seas and keep the economy going. Japan needed to import just about everything; all of that oil from the DEI needed to be transported home, raw materials from Manchuria, Korea, and China needed to be brough to Japan. Japan couldn’t even feed itself without massive imports of rice and other foodstuffs. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [August 26, 2013, 3:02pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/82 "2013-08-26T15:02:07Z")
> [@Exapno\_Mapcase](#): > > You don’t have to go back that far. [In the] classic Philip K. Dick novel, _The Man in the High Castle_… he has Japan controlling only the west coast, with the Rockies as a buffer territory between them and the German-controlled eastern half the country… Although it’s far-fetched, I liked that book too. But I thought the Japanese and the Germans split the U.S. at the Mississippi River? ---
**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:** [August 26, 2013, 3:39pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/83 "2013-08-26T15:39:19Z")
> [@Bremidon](#): > > Thanks for taking the time to explain your opinions and your analysis. Let me respond. > > 1. Citing the documentary. Agreed that it sucks that I didn’t tape it. I was asked to name the doc, and I did. We’re kind of moving the goalposts here, although I’m absolutely convinced that this is where the goalposts should have been in the beginning, if we are going to try to follow this one thread to the end. It’s not really moving the goalpost. The assertion is without merit, so we don’t normally allow that to slide by, especially in GQ. > [@](#): > > 1. Secret buildup of transports. This is argument you make that is most convincing to me. Could Japan have possibly held such a large project secret? Doubtful, maybe even implausible, but certainly not impossible. In a cold analysis, I would agree with you 100%. Would I have agreed in December, 1941? I’m not sure. Give me time to think about this and see if I can come up with anything else to add any strength to this idea. Ironically, Japan was dependent on its soon to be enemies for shipping. She lost 50% of her transportation capabilities by declaring war and only through the subsequent invasions would she regain 25% of that back, but that wouldn’t be for a month or so. Everyone knew that Japan could not beat the US in a protracted war. The Japanese knew it, we knew it. The game plan by the Japanese was to shock the US with major defeats at Pearl Harbor, cease enough islands to make a strong defensive barrier in the Pacific and then let us tire ourselves out. They thought we could then sign a peace treaty allowing them to keep China and the DEA. Even if the Japanese had had the logistic capabilities of mounting an invasion of the US, which they didn’t have and our military leaders and the administration knew that, it made zero military sense for them to do so. It would have taken millions of troops to invade the US, plus airplanes which the Japanese didn’t have, tanks which they didn’t have and land transport which they didn’t have. You simply cannot mount a large scale invasion of a hostile country from across an ocean. It simply does not work. It has to be staged. You need local air support. You need fuel. You have to move your landing ships over and have some place to group them. In 1941, the Japanese could not have launched an invasion of Hawaii, let alone the West Coast. During the Pearl Harbor attack, one of the factors for not launching a third wave was that the destroyers would be running too low of fuel. That was for a small fleet. Even if they had had a fleet, they didn’t have enough fuel stockpiled in Japan for the invasion. The idea is completely without merit. For the question if you would have agreed on December 7, with all due respect, it doesn’t matter. The question is if the military or administration panicked and there is nothing on record which suggests that. > [@](#): > > 6)Once it became clear that the pre-war analysis was incorrect and that the capabilities of the enemiy had been underestimated, where can you stop the fall? What part of that pre-war analysis is immediately salvagable? On December 7th, all that the Japanese had done was to demonstrate they had a capability of carrying out surprise attacks. That’s it. The real shock to the US military was the subsequent attacks on Malay, PI, Singapore, Hong Kong, DEA and the other islands, when the Allies started to get their asses kicked for the first several months. However, there was never a question of the Japanese invading the US mainland. > [@Dissonance](#): > > As someone said, a politician or two may have panicked, but the idea that any of the military leadership or high level political leadership took the threat of a Japanese invasion of the mainland seriously is absurd, much less the idea that the Army was drawing up plans to fall back to Chicago. I couldn’t have said it better. Oh, I guess that I did say it. 😃 ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [August 26, 2013, 4:17pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/84 "2013-08-26T16:17:41Z")
> [@Elendil\_s\_Heir](#): > > Although it’s far-fetched, I liked that book too. But I thought the Japanese and the Germans split the U.S. at the Mississippi River? I was going by this [obsessively detailed fan map](http://upload.wikimedia.org/wikipedia/en/8/8d/Man_in_the_Hight_Castle_Dick.png) on the Wikipedia page. Bremidon, what Robert McNamera famously described as the “fog of war” is quite real, but it is not impenetrable. Consider what the U.S. already knew by the end of 1941. Control of the sea is hugely - if not all - important. There was far more worry about the Atlantic coast than the Pacific coast because of German submarine warfare attacking supply ships. The size of the Pacific and the lack of an equivalent Japanese attack force insured that an invasion force would effectively be a suicide mission, something unthinkable at the start of the war when the Japanese were moving into a dozen territories at once, needed every man and ship, and were totally confidence of winning. The Germans had also called off their invasion plans for Britain, in large part due to this lack of control and to the lack of control of the air. Please read the [Operation Sea Lion](http://en.wikipedia.org/wiki/Operation_Sea_Lion) page at Wikipedia. If the Germans could not pull this off with all of northern Europe at their back, it was pure pulp to imagine the Japanese doing this over 5000 miles of empty ocean. We had broken the Japanese naval codes. This was not a panacea, since the traffic was sketchy, it took long periods of time to decrypt, and codes were changed frequently, but it meant that we had basic knowledge about Japanese plans and movements. The necessary few clues were not broken in time to ward off Pearl Harbor, but in the longer term a U.S. invasion force preparation would have stuck out from everything else. You seem to be supposing that because Pearl Harbor was a surprise, anything could happen. From my very first post to you through all those from others supplying large amounts of information from other angles we’ve been offering mountains of evidence that nobody at any time ever took a west coast invasion - much less a battle across the country - seriously. This is not attacking a straw man. You made the claim, and then kept defending its plausibility. Your arguments for that defense are nothing more than your personal belief that it could have happened. Yet you admit, and demonstrate, a complete lack of understanding of the period, or of basic logistics. You claim your stay in Germany has given you access to different viewpoints. You have not indicated what those are or how they are relevant to this particular topic. You keep insisting that something might be out there and we are required to prove to you that you are wrong. Amazingly, we have patiently and repeatedly done so, although I lost my patience a while back. I will repeat one thing: there’s no there there.\* - If you don’t understand that idiom (I don’t know your level of English, although your posts are excellent) try [this page](http://www.urbandictionary.com/define.php?term=there%27s%20no%20there%20there). ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [August 26, 2013, 4:44pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/85 "2013-08-26T16:44:23Z")
It’s just preposterous to think that anyone in the military would have considered that for a Japanese invasion of the US mainland, the defensive positions would have been Iowa or Illinois. Do you realize just how far that is? It’s over 1500 miles inland, across the Fucking Rocky Mountains. Let’s assume for a moment that Japan’s capabilities were vastly underestimated. Further, let’s assume for some reason they would consider abandoning China to do an invasion of the US mainland purely for psychological factors, to pressure the US into caving. So they land in California and Washington state. What plan has them marching across the US continent? In what way does driving their invasion toward Chicago make any sense? What would they be trying to accomplish? And how are they going to get there? ---
**Author:** ![Dissonance](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@Dissonance](https://boards.straightdope.com/u/Dissonance)\ **Post date:** [August 26, 2013, 6:14pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/86 "2013-08-26T18:14:06Z")
> [@TokyoBayer](#): > > I couldn’t have said it better. Oh, I guess that I did say it. 😃 I was half falling asleep when I wrote that post and couldn’t remember who said it, sorry about that. 😃 ---
**Author:** ![Daylate](https://avatars.discourse-cdn.com/v4/letter/d/9dc877/32.png) [@Daylate](https://boards.straightdope.com/u/Daylate)\ **Post date:** [August 26, 2013, 7:01pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/87 "2013-08-26T19:01:36Z")
It’s funny how these weird ideas start. My mapping program shows that the distance from Chicago to the Pacific Coast is almost 1,900 miles. And a few thousand Japanese soldiers are going to cover that distance, conquering as they go? How much gasoline would have been required for the trucks alone? I have a mental image of battalions of Japanese soldiers lining up at Greyhound terminals, all buying tickets for Chicago. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [August 26, 2013, 8:27pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/88 "2013-08-26T20:27:20Z")
> [@Exapno\_Mapcase](#): > > I was going by this [obsessively detailed fan map](http://upload.wikimedia.org/wikipedia/en/8/8d/Man_in_the_Hight_Castle_Dick.png) on the Wikipedia page… Hmm. That’s not how I remember it. I should look it up again. > [@Daylate](#): > > …I have a mental image of battalions of Japanese soldiers lining up at Greyhound terminals, all buying tickets for Chicago. “One at a time, buddy, and put your Arisaka in the overhead compartment, would ya…?” ---
**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:** [August 27, 2013, 2:46am UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/89 "2013-08-27T02:46:26Z")
The premise of the documentary is so fundamentally flawed, it’s simply absurd. While the US didn’t know a lot on the evening of December 8th, we did know that the Japanese were not in a position to invade the US. Not in the next three months, not in the next 10 years. The military would know that. Roosevelt, as a former Assistant Secretary of the Navy would know that. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [August 27, 2013, 4:50am UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/90 "2013-08-27T04:50:12Z")
> [@TokyoBayer](#): > > The premise of the documentary is so fundamentally flawed, it’s simply absurd. > > While the US didn’t know a lot on the evening of December 8th, we did know that the Japanese were not in a position to invade the US. Not in the next three months, not in the next 10 years. > > The military would know that. Roosevelt, as a former Assistant Secretary of the Navy would know that. Certainly thoughts of air or sub raids on CA were there, and even planned for. But that’s raids, not invasions. ---
**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:** [August 27, 2013, 6:28am UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/91 "2013-08-27T06:28:38Z")
> [@Irishman](#): > > It’s just preposterous to think that anyone in the military would have considered that for a Japanese invasion of the US mainland, the defensive positions would have been Iowa or Illinois. Do you realize just how far that is? It’s over 1500 miles inland, across the Fucking Rocky Mountains. Yes, what natural terrain would give the best advantage to defending US forces? The flat lands of Iowa or Illinois? or the mountains that make up large parts of California, Utah, Colorado, etc? Even if the military feared a Japanese invasion, on what rational basis would they flee one of the best natural defences of the United States, and make their defence in areas that had little by way of land features to multiply their defence forces? ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [August 27, 2013, 2:33pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/92 "2013-08-27T14:33:52Z")
> [@Bremidon](#): > > Oh dear. Does anyone have a reputable site where I can research WWII? Between all the sites that jump straight rom PH to Midway, the references to the History Channel, and the CT site, I’m going nowhere fast. > > I’m going to have to give up for the moment anyway. I was hoping that the ICE would have a better Internet connection that the resional, but it’s turning out to be worse. Oh well. 🙂 Online websites I don’t have; I get most of my detailed knowledge from books. My go-to overview of WWII in general is John Keegan’s _The Second World War_. For more detail on the Pacific War, _Eagle Against the Sun_, by Ronald Spector. For specifics about the Japanese carrier force, although it’s focused on Midway, _Shattered Sword_ by Jonathan Parshall and Anthony Tully. ---
**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:** [August 27, 2013, 3:09pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/93 "2013-08-27T15:09:04Z")
> [@DrDeth](#): > > Certainly thoughts of air or sub raids on CA were there, and even planned for. But that’s raids, not invasions. In contrast to the impossibility of an invasion of the US, some elements of the [IJN proposed to invade Australia in 1942](http://en.wikipedia.org/wiki/Proposed_Japanese_invasion_of_Australia_during_World_War_II), but was promptly rejected the the IJA for many of the reasons given in this thread. First, they didn’t have enough men. > [@](#): > > Japan’s success in the early months of the Pacific War led elements of the Imperial Japanese Navy to propose invading Australia. In December 1941 the Navy proposed including an invasion of Northern Australia as one of Japan’s ‘stage two’ war objectives after South-East Asia was conquered. This proposal was most strongly pushed by Captain Sadatoshi Tomioka, the head of the Navy General Staff’s Planning section, on the grounds that the United States was likely to use Australia as a base to launch a counter-offensive in the South-West Pacific. The Navy headquarters argued that this invasion could be carried out by a small landing force as this area of Australia was lightly defended and isolated from Australia’s main population centres.[2] There was not universal support for this proposal within the Navy, however, and Isoroku Yamamoto, the commander of the Combined Fleet, consistently opposed it.[3] > > The Japanese Army opposed the Navy’s proposal as being impractical. The Army’s focus was on defending the perimeter of Japan’s conquests, and it believed that invading Australia would over-extend these defence lines. Moreover, the Army was not willing to release the large number of troops it calculated were needed for such an operation from the Kwantung Army in Manchuria as it both feared that the Soviet Union would enter the Pacific War and wanted to preserve an option for Japan to invade Siberia.[4] Looking at the IJA in [December of 1941](http://en.wikipedia.org/wiki/Imperial_Japanese_Army#World_War_II), there were 1.7 million solders in 51 divisions, but 40 of the divisions were either in China or Manchuria. Tojo said that they just simply didn’t have the men and resources to carry out an invasion. And this is with Australia in their own backyard, with seized bases where they could stage an invasion and against a country smaller in population and armed forces to themselves. And > [@](#): > > In December 1941 the Navy calculated that a force of three divisions (between 45,000 and 60,000 men) would be sufficient to secure Australia’s north-eastern and north-western coastal areas. In contrast, the Army calculated that a force of at least ten divisions (between 150,000 and 250,000 men) would be needed. The Army’s planners estimated that transporting this force to Australia would require 1.5 to 2 million tons of shipping, which would have required delaying the return of requisitioned merchant shipping.[8] This invasion force would have been larger than the entire force used to conquer South-East Asia.[9] The Army also rejected the Navy’s proposal of limiting an invasion of Australia to securing enclaves in the north of the country as being unrealistic given the likely Allied counter-offensives against these positions. Due to its experience in China the Army believed that any invasion of Australia would have to involve an attempt to conquer the entire Australian continent, something which was beyond Japan’s abilities.[10] Australia in 1941 had a population of 7 million compared to the US’s 133 million. And, of course, we could look at the IJA’s inability to beat the Chinese despite it being in the middle of a civil war, a lack of competent leadership and no industrial base. Contrast that to the US. We could go on and on, but these are some reasons is why no one is taking the documentary seriously. Children shouldn’t be allowed to play with guns or put together scripts for shows. ---
**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:** [August 27, 2013, 3:14pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/94 "2013-08-27T15:14:07Z")
> [@Sailboat](#): > > My go-to overview of WWII in general is John Keegan’s _The Second World War_. For more detail on the Pacific War, _Eagle Against the Sun_, by Ronald Spector. For specifics about the Japanese carrier force, although it’s focused on Midway, _Shattered Sword_ by Jonathan Parshall and Anthony Tully. I always recommend _Hirohito and the Making of Modern Japan_ by Herbert P. Bix. It covers a lot more than just the war period, but is absolutely essential to understanding some of the dynamics of the Japanese military leadership. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [August 27, 2013, 4:54pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/95 "2013-08-27T16:54:50Z")
> [@Little\_Nemo](#): > > I got your PM on this as well. You may have a point. I’ve been checking and it does appear the British used specially designed torpedoes during the Taranto attack. But it also appears they didn’t publicize this. It may have even been classified. > > Admiral Kimmel testified that he had been told the Taranto attacks took place in deep water (ninety feet) and that attacks in shallow water like Pearl Harbor were impossible. The Japanese also believed Taranto attack had been in deep water and developed their shallow water torpedoes independently. > > So while the actual facts about the Taranto attack proved a torpedo attack at Pearl Harbor was possible, the publicly known facts about Taranto pointed towards the opposite conclusion. Kimmel claimed that? Surely prewar charts for Taranto were available; it’s not some remote atoll. I have a hard time believing nobody in the US Navy knew how deep Taranto was. For what it’s worth, [Wikipedia claims](http://en.wikipedia.org/wiki/Battle_of_Taranto#Influence_on_Pearl_Harbor) the Japanese were working on shallow-water aerial torpedoes for harbor attacks in the early 1930s. ---
**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:** [August 27, 2013, 5:11pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/96 "2013-08-27T17:11:57Z")
> [@Sailboat](#): > > For what it’s worth, [Wikipedia claims](http://en.wikipedia.org/wiki/Battle_of_Taranto#Influence_on_Pearl_Harbor) the Japanese were working on shallow-water aerial torpedoes for harbor attacks in the early 1930s. From your cite: > [@](#): > > However, the Japanese had been working on shallow-water solutions since early 1939, with various shallow ports as the notional targets, including Manila, Singapore, Vladivostok, and Pearl Harbour.[19] In the early 1930s the Japanese were using a breakaway wooden nose to soften the torpedo’s impact with the water.[19] By mid-1941 the Japanese perfected breakaway wooden fins for added aerial stability I take that to mean that they had been working on the shallow water solution since 1939 but that they had used the breakaway nose since the early 30s, but not necessarily for a shallow water solution. [This cite](http://www.richardsorge.com/excerpts/1940/) claims that the Taranto attack did influence not only the Japanese but also prompted Navy Secretary Knox to warn Kimmel > [@](#): > > Within a week of the Taranto Attack the Japanese Navy sent Lt. Commander Naito Takeshi to Taranto to “investigate the attack and estimate the damage.” Naito shared the results of his visit to Taranto with Genda Minoru - the soon to be executive planner and strategist of the Pearl Harbor attack and protege of Admiral Yamamoto - who from his office in London quickly forwarded a report of the attack to Tokyo. The close study of Taranto by the Japanese enormously influenced Admiral Yamamoto’s plan to develop his own shallow water torpedo. Prior to Taranto the Admiral "assumed that his pilots would need to develop the highest possible bombing accuracy… [and that] he could not use aerial torpedoes which were devastating ship killers, because Pearl Harbor’s shallow depth was insufficient for an air-launched torpedo’s requirement of roughly 70 feet122 ". Taranto changed all that, for the Japanese discovered that the British had modified their torpedoes for shallow water123. From this intelligence the Japanese would learn how to reconfigure their torpedoes using wooden fins that facilitated operations in shallow water (the British shallow water design was different, but nonetheless inspirational)124. (Prange, At Dawn We Slept, p.320; Volkman, p.182) (See also Appendix IV entitled “Taranto,” October 10, 1941, late October 1941, November 11-13, 1941, and December 6, 1941). > In response to the British Attack on Taranto U.S. Secretary of the Navy Henry Knox orders that the “highest priority must be given to getting more interceptor aircraft, AA guns, and additional radar equipment” in order to protect Pearl Harbor against a surprise attack. Knox also suggested to then Rear Admiral, Commander of Cruisers, Battle Force, and soon to be Admiral and Commander in Chief of the United States Fleet Husband E. Kimmel, that anti-torpedo net barriers should be installed as a protective measure in the Harbor. Kimmel rejected the idea because it “would restrict boat traffic by narrowing the channel.” (Costello, The Pacific War, pp.83-4) ---
**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:** [August 27, 2013, 5:33pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/97 "2013-08-27T17:33:41Z")
The result of some less sleep on this side of the pond and research on Google. > [@](#): > > B. CORRESPONDENCE ON ANTI‑TORPEDO BAFFLES IN PEARL HARBOR > > On February 15, 1941 (Exhibit 49), the Chief of Naval Operations wrote to CincPac regarding anti‑torpedo baffles for protection against attacks on Pearl Harbor. This stated that the shallow depth of water limited the need for anti-torpedo nets in Pearl Harbor and the congestion and the necessity for maneuvering room limited the practicability of the present type of baffles. The letter indicated that a minimum depth of water of 75 feet might be assumed necessary successfully to drop torpedoes from planes and that the desirable height for dropping is 60 feet or less. There were various other considerations stated. The recommendations and comments of the Commander‑in‑Chief were especially desired. A similar letter was sent by the Chief of Naval Operations to the Commandants of various Naval Districts, including the Fourteenth, on February 17, 1941 (Exhibit 54). > > The reply to the request for recommendations and comments was made on March 20 1941, in a letter by Admiral Bloch, stating that the depth of water at Pearl Harbor was 45 feet, and for that and other reasons, he did not recommend anti‑torpedo baffles. CincPac agreed, until such time as a light efficient net were developed (page 293). > > In June, 1941, the Chief of Naval Operations sent another letter to the Commandants of Naval Districts, copy to CincPac and others, referring to recent developments, and to experience at Taranto, which stated that no minimum depth of water could be assumed safe as regards torpedo attack if there were sufficient water around a ship to permit an attack to be developed and a Sufficient run to arm the torpedo, but that such attack in 10 fathoms or more was more likely than in shallow water (Exhibit 55). The torpedoes at Taranto, > > 404 CONGRESSIONAL INVESTIGATION PEARL HARBOR ATTACK > > it was said, were launched in thirteen to fifteen fathoms although some may have been in eleven. > > Admiral Kimmel testified that on this correspondence he based his opinion that there was no chance of an air torpedo attack on Pearl Harbor—and that even after the June letter, he did not think torpedoes would run in such shallow water. He pointed out that the Navy made no effort to place such nets in Pearl Harbor (page 293). He later stated that he did not think an aerial torpedo attack would be made because he did not think such torpedoes would run in Pearl Harbor and did not give this a great deal of consideration for that reason (page 331. I think we can safely conclude that there was not testimony from Kimmel stating that the Taranto attack was done in 90 feet. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [August 27, 2013, 5:43pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/98 "2013-08-27T17:43:36Z")
> [@TokyoBayer](#): > > From your cite:I take that to mean that they had been working on the shallow water solution since 1939 but that they had used the breakaway nose since the early 30s, but not necessarily for a shallow water solution. OK, maybe. It sounded like the breakaway nose would be useful for shallow-water drops, but it could mean something different. [This cite](http://www.richardsorge.com/excerpts/1940/) claims that the Taranto attack did influence not only the Japanese but also prompted Navy Secretary Knox to warn Kimmel [/QUOTE] Interesting website – the web address jumped out at me immediately, considering who [Richard Sorge](http://en.wikipedia.org/wiki/Richard_Sorge) was. The footnote to the part you quoted is somewhat more explicit: > [@](#): > > 123 Most, if not all, American books and articles misstate the history of the torpedoes at Taranto and Pearl Harbor. The literature articulates that the British had fitted their torpedoes with special wooden fins later copied and fine-tuned by the Japanese. The British tested, but did not use wooden fins. Instead, they “used a fine wire cable, coiled on a drum, which connected plane and torpedo. When the torpedo was dropped, the carefully calculated length and breaking point of the wire placed the falling torpedo at the correct depth and angle.” At Taranto the Swordfish had to be traveling at an altitude of 150 feet at slow speed in level flight or with nose slightly down for the weapon to be released. The water depth could not be less than 33 feet, and the distance to the target had to be greater than 900 feet in order for the torpedoes to arm themselves. The modified Japanese version used at Pearl Harbor, however, was far more ingenious and accurate, not requiring the cumbersome wire system of the British shallow water weapon. Japanese engineers instead used a “breakaway wooden fin to stabilize running depth and angle.” Two British torpedoes were found in the harbor without exploding, and were left for Italian, and eventual Japanese inspection (one torpedo was found floating in the harbor, its striking head crushed but the warhead undetonated, another under the Littorio’s keel. This torpedo affair is not trivial. It is pivotal to the understanding of the relationship between the two attacks. (Lowry and Well ham, pp.88-91; Smithers, p.111 Not sure whose words those are: Sorge’s, the site’s editor, or someone he’s quoting. ---
**Author:** ![jsutter](https://avatars.discourse-cdn.com/v4/letter/j/8e8cbc/32.png) [@jsutter](https://boards.straightdope.com/u/jsutter)\ **Post date:** [August 27, 2013, 6:48pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/99 "2013-08-27T18:48:39Z")
> [@Gray\_Ghost](#): > > As an aside to **Sailboat** ’s point about the disadvantage of losing the U.S. fleet at Pearl, I’ve read that in some ways, it was a ‘blessing’ to have had the battleships sunk there. The logic was that, if the battleships weren’t sunk there, they’d have sortied against the IJN in v. late 1941 and early 1942, and been sunk in deep water by aircraft. Like HMS Prince of Wales and Repulse. Getting them sunk at Pearl allowed them to later be raised and available in for shore bombardments during the amphibious landings from 1943-1945. Except for USS Arizona and Oklahoma, of course. > > … And wasn’t it convenient that our carriers happened to be out of town for the event? 😉 ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [August 27, 2013, 7:34pm UTC](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628/100 "2013-08-27T19:34:43Z")
Interesting posts…why was it that the Japanese dive bombers neglected to hit the oil storage tanks at Pearl Harbor? Losing that much oil would have crippled the fleet, just s well as sinking it. [Previous page](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628.md?page=4) [Next page](https://boards.straightdope.com/t/question-regarding-the-attack-on-pearl-harbor/666628.md?page=6)