Why did Japan think attacking Pearl Harbor was a good idea?

[Jackmannii]

@MarvinKitFox

If the Pearl Harbor attack had managed to strike its actual targets, the US carrier fleet?
Then YES, the US would have sought a diplomatic resolution.

This sounds like what the Japanese believed (and kept irrationally believing through much of the war). Just win an overwhelming victory against the weak, democratic, pleasure-loving Americans and they’ll sue for peace.

“Big mistake, Indy! Big mistake!!”

[postpic200]

@HubZilla

Inspired by this thread, what did the Japanese think would happen after Pearl Harbor? Yamamato feared “they had awoken a sleeping giant”. While I know the quote isn’t real, it implies most other Japanese leaders did not fear a sleeping giant would awake.

So, why did they think a larger industrialized country with enormous resources would not be filled with terrible resolve? That the Japanese would raid Pearl Harbor and the American go “You got us, we’ll stop bothering you”. Even if it was a pre-emptive strike to prevent interference to the Philippines and Southeast Asia, did they really think the US military would say “They took out our Pacific Fleet, may as well leave them alone, no need to rebuild or challenge them”.

Hindsight is 20/20, Pearl Harbor was a mistake, and we did rebuild a gigantic navy and basically destroyed their country. Why did the Japanese think anything else would happen after attacking a naval installation and declaring war? Maybe not why (they are fanatics, etc), but what else did they think would after December 7?

At the time the US Pacific fleet and the Japanese fleet were almost equal, with Japan having a slight edge. The US was building up it’s fleet, so if Japan was going to strike a blow, that was the time. The Japanese hoped that they could take the fight close if not to the US main land, then the US would then give up much of the Pacific for at least a time, giving Japan the raw materials it need to build up it’s war machine.

Also don’t forget that in the eyes of many, the US would do what the British did, appeasement and try to avoid war. At the time isolationism was seen as the way to go and until Dec 7, the US had no real reason to enter the war. Germany had worked out some compensation for the sinking of the destroyer USS Reuben James. Many in Japan’s higher command felt the US didn’t have the will to fight and win.

So a strong blow, maybe the US would give up the much of the Pacific, or Japan would have a chance to defeat the US, forcing the US to sue for peace, giving Japan the raw materials it lacked.

[Silver_lining]

@Johnny_L.A

Japan had won a war against Russia,fought with the Allies in WWI, and had a modern, British-inspired fleet. They were very confident. But there was a worldwide depression. Japan sought to expand its empire into China and Southeast Asia to secure resources for itself and solve its economic problems. But the United States was standing in the way. The U.S. embargoed many materials that Japan needed. So Japan had to move south for such things as rubber. Japan saw a war with the U.S. as inevitable. But Japan couldn’t reasonably take on the U.S. unless they evened the odds. A devastating surprise attack, it was thought, would keep the U.S. out of a war until Japan could secure its position and the foreign resources.

The idea was sound. Destroy the U.S. Pacific Fleet and bottle up our strategic base at Pearl Harbor. It almost worked, too. They hit all eight battleships were damaged, and four were sunk. At the time, battleships were the capital vessels. Maybe the Japanese didn’t understand how personally we would take an attack, because three of the sunken BBs were raised and all of the battlewagons were repaired (and upgraded). The Japanese also failed to destroy the U.S. fuel reserves in Hawaii. Had they destroyed the fuel, and had they sunk the U.S. carriers too, their plan of keeping the U.S. out of the war might have worked.

Actually, the Battleships were not the key, the Aircraft carriers were, and Japan sunk zero of them. When the general asked how many aircraft carriers did Japan sink during the attack, and the answer was zero, he knew he was in trouble.

Japan had lousy generals. Prior to the Attack all of the Aircraft Carriers went out to sea. If they were wise they would have sent a spy or two out to Hawaii, to confirm which boats were in the harbor before attempting a surprise attack.

[Johnny_L.A]

@Silver_lining

Actually, the Battleships were not the key, the Aircraft carriers were…

From what I read, the thinking at the time was that battleships were the capital ships. WWII proved the aircraft carriers were the ships to beat.

[Mr.Miskatonic]

@Johnny_L.A

From what I read, the thinking at the time was that battleships were the capital ships. WWII proved the aircraft carriers were the ships to beat.

That’s pretty much the case. The mindset was that the BB was the instrument of war. Its why Japan was building such pigs as the Yamato and her sister ship. Carriers were kind of an accident born from Naval treaties (before then they were mostly just curiosities) and the oddball look of Japanese carriers (which were mostly BB conversions). The Akagi had sets of 8 inch deck guns on the sides for crying out loud.

Early WW2 showed that the carriers were actually more crucial.

Mind you, some historians have argued that Battleships were obsolete the moment the first smaller ship fired a long-range torpedo into the water but Admirals were too fond of their big gunned capital ships. There is something to that argument.

[Johnny_L.A]

@Mr.Miskatonic

The Akagi…

From Wiki:

At 04:50 on 5 June, Yamamoto ordered Akagi scuttled, saying to his staff, “I was once the captain of Akagi, and it is with heartfelt regret that I must now order that she be sunk.” Destroyers Arashi, Hagikaze, Maikaze, and Nowaki each fired one torpedo into the carrier and she sank… Two hundred and sixty-seven men of the ship’s crew were lost…

You’d think they’d have gotten them off first! :eek:

[Great_Antibob]

Indeed so. Battleships were considered at the time to be the basis around which to build fleets. The Pacific war forced a re-evaluation.

Japan was keen on building more battleships (like the Yamato and super-Yamato class) but never had the time or resources to pull it off. And by late in the war, it was clear that the era of the battleship was done, anyway.

The US, having lost most of its battleship fleet, didn’t have much choice but to switch to a carrier based approach, which ended up being a bit of a blessing.

If the Japanese were disappointed by not getting the carriers at Pearl Harbor, it wasn’t because they especially recognized that carriers would displace battleships but because they needed to get all the capital ships or at least as many as possible and letting any slip away would come back to bite them.

[OttoDaFe]

Nitpick: it was the Kaga that had 8" guns — which were located so close to the waterline that they weren’t even conceivably much use.

And she wasn’t alone: both the Lexington and Saratoga mounted 8" guns in four double turrets (and the Lex still had hers when she was sunk at Coral Sea).

[bowlweevils]

The arguments that war with the US was seen as inevitable because of the Japanese actions in east Asia can be made much more specific.

Japan was going to invade Philippines, a US colony. Japan believed it had to make as effective an attack as possible against Pearl Harbor to have any chance to induce the US to take a loss of Philippines as just a lost colony not worthy of a real fight over.

And Japan invaded Philippines 10 hours after starting the attack on Pearl Harbor.

[bowlweevils]

@Little_Nemo

But an attack on the East Indies would be primarily a naval war. And the Japanese navy was available for use in 1941.

There’s no need to discuss the East Indies as a hypothetical. Japan invaded the East Indies on December 17 1941, as it had been planning for months. The campaign finished in Japanese victory and official withdrawal of the allies on March 1 1942.

[Capn_Carl]

@OttoDaFe

Nitpick: it was the Kaga that had 8" guns — which were located so close to the waterline that they weren’t even conceivably much use.

And she wasn’t alone: both the Lexington and Saratoga mounted 8" guns in four double turrets (and the Lex still had hers when she was sunk at Coral Sea).

Nitpick nitpick: Akagi also had 8” guns.

[Little_Nemo]

@bowlweevils

There’s no need to discuss the East Indies as a hypothetical. Japan invaded the East Indies on December 17 1941, as it had been planning for months. The campaign finished in Japanese victory and official withdrawal of the allies on March 1 1942.

What makes you think I was presenting this as a hypothetical?

[RockysDAD]

I don’t know the answer to why the Japanese military at the time of Pearl Harbor thought it a wise move, but just consider:

(a) The U.S. was still in the Great Depression. Industrializing to get war machinery to Europe (mostly the UK) was what was bringing the U.S. out of depression.

(b) Japan with full cooperation from the U.S. had become an empire by taking over, years before Pearl Harbor, a lot of China and all of Korea.

© Really, what was more brazen? The attack on Pearl Harbor or the attack on The World Trade Towers.

I am an American living in Japan. Modern Japanese people question that event in history almost as much as others might.

[Little_Nemo]

@RockysDAD

Japan with full cooperation from the U.S. had become an empire by taking over, years before Pearl Harbor, a lot of China and all of Korea.

No, not at all. The United States was opposed to Japanese expansion, pretty much from the start. Japanese expansion occurred at the expense of American economic interests.

[TokyoBayer]

The following exchange perfectly demonstrates why my interest in participating in these threads has dwindled.

Little Nemo makes an argument and throws out a factoid supporting it:

@Little_Nemo

We can see, in retrospect, that American economic strength would be converted over to military production and how quickly this would occur. But that wasn’t obvious at the time. The United States was a negligible military power in 1941.

Most countries spent years building up their military forces; Japan and Germany had. So they assumed that it would take the United States a similar amount of time. They didn’t expect that America could achieve military parity with them, much less military superiority, until some time around 1950.

So from the Japanese point of view, the American navy was the only threat America had in existence in 1941; its army and air forces were still on the drawing board. Cripple the navy and America would be helpless for several years. Japan could secure an impregnable position and dictate terms.

My bolding.

I have no idea where this curiously specific, yet entirely false assertion comes from.

So I respond:

@TokyoBayer

This is silly. Certainly, unless the Japanese were absolute idiots not paying attention to the States, then they would have know about the very public Two-Ocean Navy Act of 1940:

(I copied the list of the greatest naval build up in peacetime history)

There simply can’t be any reason to believe that the Japanese would expect the US to take until 1950 to achieve parity. That’s silly. There were enough Japanese who were familiar with the capability of the States.

So, here is a specific argument that the Japanese would know that it would not take nine years to build up equal, let a long superior forces. Mind you, this was peacetime development and not even when the country was on war footing.

The response:

@Little_Nemo

Is the United States capable of paying off the national debt? Yes, certainly. Do you think it’s likely that the national debt will be paid off by 2028? No, almost certainly not. We lack the political will to do something we know we should be doing.

Rather than engage with me and respond to the actually numbers then we get a completely irrelevant, pointless and false analogy. The initial argument was absurd, based on nothing but how someone imagines how the Japanese might be thinking rather than on what they actually were.

Here is what we know, from the respected author of a well-researched book on Pearl Harbor, he give us this as well.

The Japanese calculated that the Americans were building three to five tons of warships for every ton coming out of Japanese yards and that by 1944 the fleet tonnage ratio would be ten to three. The Japanese needed to lure the Americans into a decisive battle quickly, while the fleets were roughly comparable.

Compare that to

That’s the key point that the Japanese and Germans saw in 1941. The United States had a huge economy; but it wasn’t focused on military production.

Simply no.

One of the key reasons the Japanese acted when they did was because they knew that the US was building up a massive force which would overwhelm them and make their 艦隊決戦 Kantai Kessen; “naval fleet decisive battle” impossible.

[soapbox] If one is not familiar with the Decisive Battle Doctrine, then one cannot understand the Pacific War. End. Of. Story. [/soapbox]

The IJN believed that in one stoke, they would destroy the American fleet and win the war.

According to the first stage of the battle plan, fast attack submarines would first be used to weaken the American fleet by 10%, then Japanese bombers from land bases and aircraft carriers would inflict another 10% casualty rate. Air strikes launched from the Japanese carriers would neutralize the American carrier fleet. Fast attack battleships and heavy cruisers, likely operating at night, would then sink or scatter enemy cruiser and destroyer screening formations to allow massed light cruiser and destroyer attacks on the US battleships using long-distance torpedoes. According to plan, this moment would be the “decisive” stage of the decisive battle, when the battleships of the Combined Fleet, centered on the modern Yamato class, would join the battle against the US battleships. Finally, the older battleships would join the fray and mop up the surviving remnants of the American fleet.

The Kantai Kessen dictated their choices of weapon development, ships built, strategies, tactics, training and leadership. It lead to the disaster at Midway. It made for poor planning at Pearl Harbor. It lead them to build superior torpedoes and superior night fighting abilities, which plagued the US in the 1942 naval engagements in the Ironbottom Sound, until advances in radar, tactics and training finally allowed the US to match and then surpass the IJN.

It was a reason why Japanese fleet submarines were focused on enemy warships rather than on transports. Hell, it’s a reason why the Japanese voluntarily went into a unwinnable war to begin with.

It was not – ever – that the Japanese believed they could beat the mighty US because it would take until 1950 for the Americans to achieve military parity. It was that they believed they had a strategy which would allow them to defeat a somewhat superior force, but they also recognized that time was running out.

[TokyoBayer]

Following up on the previous post in which is quoted:

The Japanese calculated that the Americans were building three to five tons of warships for every ton coming out of Japanese yards and that by 1944 the fleet tonnage ratio would be ten to three. The Japanese needed to lure the Americans into a decisive battle quickly, while the fleets were roughly comparable.

Looking at the book, he adds that the Japanese had calculated that the US shipbuilding capacity would likely double during war, while the Japanese capacity was already at maximum.

While it’s certainly very true that the Japanese believed their fighting spirit – Yamato-damashii (大和魂, “Japanese spirit”) – to be unequaled by any, and that this would compensate for the superior industrial capacity, there simply isn’t any mention anywhere that any of the leaders believed that the US lacked the ability to produce products. That frankly is absurd.

Alan Zimm explains that “the Japanese had little chance for victory in a long war, so they adopted a short war strategy. They built their forces for it and trained their men. They had no solution for the ‘long war’ scenario–to they ignored it.”

[TokyoBayer]

@Mr.Miskatonic

Zimm, in his book “Attack on Pearl Harbor”, notes that if the Japanese attack the oil fields, and had their absolute best day (i.e. managed to match their best training runs with no opposing aircraft and AA fire) they might have made hits on 25% of the tanks.

Zimm’s book is interesting. I’m not sure what is being asked of you, that somehow an offhand comment from an admiral, given completely without context is somehow more authoritative than carefully documented and researched scholarly work.

From a message board, someone has saved us the trouble of retyping Alan Zimm’s arguments.

"Alan Zimm has quite firmly debunked the myth that destroying the oil tank farms would have been easy. As oil silos would take hits, more flames and smoke would obscure the targets. There would be plenty of misses. They could not have been strafed. These were big oil silos with thick sides, floating tops (no oxygen inside the silos), fire suppression systems, berms to prevent leaking fuel from spreading to other silos, and good spacing between them. To overcome such defences, the Japanese would have needed to crack the tanks open with bombs to light them up. I’m not sure if the 60kg bombs that the A6M2s could carry would have done it (I highly doubt it), but in all likelihood they would have needed to use 250kg bombs carried by the D3A1s. Even if theoretically one could light fuel oil inside an oxygen free silo with a fire suppression system by strafing it, the Japanese aircraft capable of strafing which took part in the attack were armed with 7.7mm MGs (D3A1s with 2x7.7mm) and 20mm cannon (A6M2 Model 21s with 2x7.7mm and 2x20mm). The Japanese did not use AP or API ammunition like the Americans. They used AI and fuseless HE in their 7.7mm MGs and several different kinds of HE in their 20mm cannon. These shell types were great for destroying aircraft, but were useless for punching through the thick skin of oil silos.

Overall, Alan Zimm’s conclusion (accepted within the academic community) was that the Japanese could have done significant damage to the oil tank farms (though certainly not 100% destruction as people kind of just assume), but at the cost of a full wave of dive bombers. The results would have been the USN pulling tankers over to Pearl to act as temporary fuel storage while new oil silos were constructed (and the underground facilities then under construction would have no doubt been accelerated). Zimm gave a window for inconveniencing the Pacific Fleet of a few months. Nowhere near the apocalyptic appraisals of Kimmel, Nimitz and the older historiography.

One can still debate whether or not the value of hitting the oil tank farms was better than, say, hitting various light fleet units in harbour. I don’t really have a firm opinion myself, as the argument against bombing the oil tank farms isn’t nearly as slam dunk as the silly “destroy the port facilities” nonsense. The Japanese ended up doing neither option anyway, and instead the majority of the second wave dive bombers blew their loads on Nevada (other BBs too IIRC). This is very recent scholarship, so it hasn’t yet leaked into the popular conception of the battle. That process can take years, if not decades. The popular understanding of most of WWII is typically 30-50 years out of date compared to where the academic community currently is, simply because the vast majority of people don’t have time (or the ability in the case of academic journals) to read the newest books and, more importantly, journal articles on any given subject."

It seems that the myth that the oil tanks were particularly vulnerable is one of those things that everyone knows and simply accepts. It’s interesting to read books such as Zimm’s “Attack on Pearl Harbor” which are more authoritative.

Also, thank for you letting us know the price for the kindle version. I hadn’t read it before and it’s a good fine.

[John_DiFool]

@Great_Antibob

Indeed so. Battleships were considered at the time to be the basis around which to build fleets. The Pacific war forced a re-evaluation.

Japan was keen on building more battleships (like the Yamato and super-Yamato class) but never had the time or resources to pull it off. And by late in the war, it was clear that the era of the battleship was done, anyway.

The US, having lost most of its battleship fleet, didn’t have much choice but to switch to a carrier based approach, which ended up being a bit of a blessing.

Note it was Pearl Harbor specifically which initiated the sea-change in American doctrine.

@TokyoBayer

The IJN believed that in one stoke, they would destroy the American fleet and win the war.

According to the first stage of the battle plan, fast attack submarines would first be used to weaken the American fleet by 10%, then Japanese bombers from land bases and aircraft carriers would inflict another 10% casualty rate. Air strikes launched from the Japanese carriers would neutralize the American carrier fleet. Fast attack battleships and heavy cruisers, likely operating at night, would then sink or scatter enemy cruiser and destroyer screening formations to allow massed light cruiser and destroyer attacks on the US battleships using long-distance torpedoes. According to plan, this moment would be the “decisive” stage of the decisive battle, when the battleships of the Combined Fleet, centered on the modern Yamato class, would join the battle against the US battleships. Finally, the older battleships would join the fray and mop up the surviving remnants of the American fleet.

I think that, if they had waited for just such an open-ocean battle that the results would have been much worse for the US, since the Japanese capabilities in the realm of carrier aviation would have been relatively unknown (and our guys would have been even more green than they were at Midway). By doing the Pearl Harbor raid the IJN basically blew the cover off of its secret weapon-you want to wait until a truly crucial juncture to unleash something that you opponents aren’t expecting.

Only, however, if the US had tried to fight the way the Japanese expected them to (see above). 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.

[Jackmannii]

@TokyoBayer

It was not – ever – that the Japanese believed they could beat the mighty US because it would take until 1950 for the Americans to achieve military parity. It was that they believed they had a strategy which would allow them to defeat a somewhat superior force, but they also recognized that time was running out.

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.

[Mr.Miskatonic]

@TokyoBayer

Zimm’s book is interesting. I’m not sure what is being asked of you, that somehow an offhand comment from an admiral, given completely without context is somehow more authoritative than carefully documented and researched scholarly work.

Well, he also quoted an economist and a tourism webpage. So obviously I am wrong and should admit as much.

From a message board, someone has saved us the trouble of retyping Alan Zimm’s arguments.It seems that the myth that the oil tanks were particularly vulnerable is one of those things that everyone knows and simply accepts. It’s interesting to read books such as Zimm’s “Attack on Pearl Harbor” which are more authoritative.

Ah yes, thank you for finding that. My google-fu was not cutting it.

IIRC, A couple of Zimm’s major points was to look at the Japanese bomber’s training runs and generously give them that percentage (where they were trying hit much larger, ship-sized targets and were unmolested during the attacks). Then extrapolated what would happen from there.

The issues for such an attack were:

a) A direct hit from a bomb might crack or breach the tanks. Nothing else in the Japanese carrier plane arsenal was going do to anything. But hey, I was assured the sides of those huge oil tanks were only 1/2" steel thick. So what do I know.

b) A breach was not an assurance of a fire start, given the high ignition temp nature of fuel-oil, their oxygen-free storage, and fire suppression systems. Plus the fact that each tank is in its own berm means the fire isn’t going to spread if they get started.

c) These weren’t just piles of oil in cans. There were pumping mechanisms so that if a breach happened they could pump the remaining oil into other tanks. In addition the tanks were not all full and the Japanese pilots would have no way of knowing which tanks had fuel and which didn’t

So yeah, you could manage some damage if you committed the entire dive-bomber force and accepted the rapidly increasing casualties you are taking (casualties had doubled from the first to second waves as the US had manned its guns and even managed to get some planes in the air). In balance I’d say this was not the ‘grave error’ by the Japanese as some claim.

Also, thank for you letting us know the price for the kindle version. I hadn’t read it before and it’s a good fine.

My pleasure. I would have bought a copy myself to quote but I am on an iPad and Apple & Amazon are butting heads. I couldn’t even download it through Safari. :mad: