Pearl Harbor, 7th December 1939.....

So if they went ahead and committed to a concerted invasion, what key areas on the mainland would they have targeted? One factor that the Japanes would have encountered in invading the U.S., unlike many of the other places they attacked, would be an armed civilian population, too...

I would also suspect the Japanese would have included the Panama Canal as a primary target in addition to the west coast of the U.S.

I dont know US political and industrial geography well enough, but i suspect there would habve been plenty of objectives to choose from....San Diego, Los Angeles, San Francisco, later the Texas oilfields and as you say the Panama Canal.

No doubt there would have been an effective resistance in the US, but the Japanese advance would have been rapid, with any civilian resistance likley to be met with extreme barbarism on the part of the Japanese....a US equivalent to the rape of Nanking is very likley

parsifal said:

I dont know US political and industrial geography well enough, but i suspect there would habve been plenty of objectives to choose from....San Diego, Los Angeles, San Francisco, later the Texas oilfields and as you say the Panama Canal.

No doubt there would have been an effective resistance in the US, but the Japanese advance would have been rapid, with any civilian resistance likley to be met with extreme barbarism on the part of the Japanese....a US equivalent to the rape of Nanking is very likley

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The Japanese never had the amphibious and logistical assets to ever invade Hawaii, let alone the mainland US. The concept of them having this hypothetical capability is more in the realms of fantasy than "what if".

The best they could do is station a bunch of subs near the main ports and then get results as good as, or even better than what the Germans got with Operation Drumbeat.

The main Japanese thrust must always be into SE Asia, followed by advances into the shipping lanes going to Australia.

They would not be amphibious lifts in the sense western nations consider amphibious lifts, but the Japanese DID lift have the amassed capacity to lift 10 Divisions, albeit Gallipoli style, with some light landing craft to support.

The 1941 invasions were supported by the following mercantile additions:

147 troop transports, with an average dislacement of between 5 and 10000 tons, and a lift capacity for each transport of around 4000 men. 6 Hospital ships, 101 oilers and ammunition ships (not all used), 14 armed merchant cruisers, 18 aircraft transports (generally 6-8000 tons each), 6 Seaplane Carriers. Its true what you say about there being a shortage of landing ships, that would allow opposed landings to be undertaken efficiently, however, many of the merchant transports carried up to 20 Daihatsu LCs enabling them to discharge their cargoes directly across the beach, as they did in the Phillipines and Malaya.

Whilst the Japanese landing capability was not efficient, it was there, and certainly sufficient to land tens of thousands of troops in a single wave. They had the capacity to land on the continental US provided there was no great level of armed opposition. Given the state of the US army in 1939, this was a given.....

parsifal said:

Whilst the Japanese landing capability was not efficient, it was there, and certainly sufficient to land tens of thousands of troops in a single wave. They had the capacity to land on the continental US provided there was no great level of armed opposition. Given the state of the US army in 1939, this was a given.....

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And just exactly how were these light infantry divisions supposed to be resupplied?

syscom3 said:

And just exactly how were these light infantry divisions supposed to be resupplied?

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In the same way as they managed to keep their frontline forces "supplied" in the Pacific in 1942-3. At that time Japanese shipping was attempting to import supplies from South East Asia bring it home to Japan for processing, and ship out munitions to the garrisons in the central and southern Pacific. In 1942 they were supporting the equivalent of 10 divisions....in 1943 it had risen to about 20 Division, with about 30% less shipping, though I grant you by that time they were not meeting their re-supply needs.

Because of the split needs of the Japanese war machine (suppying the troops on one hand, whilst trying to organise an import regime on the other) a rough approximation is that they could utilise about 2.5 million tons of shipping for direct military needs (in fact I know they used less than that initially...about 1 million tons to be precise)

In this scenario, if all the Japanese shipping is thrown into the military effort initially, we have 6 million tons of shipping to support up to 30 Divisions in the attack forces. Given that only 4 million tons was needed to support the Anmerican forces fighting in Normandy (with ports of departure in the US), it seems entirely plausible to me that the Japanese unmotorized Infantry formations could be kep adequately supplied.

In 1939, Japan had strategic oil reserves for about two years of operations. If they captured the required resources on the US mainland, allowed say 6 months for repair of the facilities, they could use the same shipping to do two different tasks....on the outward journey they carry war munitions and replacements, on the return journey they carry raw materials plundered from the US mainland.

The question in this hypothetical is not that the Japanese could initiate the operation, but whether they could finish it. The US has great potential and great powers of recivery. If invaded like that it would take them less than a year to field a force approachiing 50 Divisions. In two years it would double. They could call on ther resources of Canada, and limited resources from England. I dont think, in the finish, the Japanese could complete the task, but they could certainly initiate it, and might have a better chance of getting a negotiated peace that then gives them a free hand in east asia

syscom3 said:

Farce?

You think the war in the Pacific was a farce?

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I never said farce. I said "face" or that which is presented for all to see.

Parsifal, it is indeed an education whenever you have your say. One thought occured to me. I would think the Japanese would have to take Hawaii as a strategic base in conjunction with landing on the west coast. It would simplify the supply chain to future operations wouldn't it? I don't think they would try to take the west coast though since the majority of the United States industrial might was in the East and it would create for the Japanese the same thing the Germans had with Russia. That is to say a very long supply chain and not able to reach the country's industrial base. What do you think?

How many of you realize that in 1939, the IJN only had four fleet carriers available?

NFN

Yes capturing Hawaii would simplify the re-supply issue. I also agree that taking the west coast does not defeat the US, not even conquests as far east as texas defeats the US. And the logistical issues are what would defeat the Japanese in the finish, though the ability for the Japanese to achieve deep penetrations of enemy territory is well demonstrated by their China incursions. The area of occupied China is bigger than France, the low countries and Germany combined.

If the Japanese capture the west coast ports or put them under threat, what is the USN, the primary weapon to retaliate, going to do. As Sys points out the Japanese only had 4 fleet carriers (assuming the hiryu is recommissioned in time), plus they had the Ryujo and the Hosho. The Japanese did have 6 seaplane carriers, to cover their landings. I dont see the USN doing very well at all in this scenario because they would have no safe bases to operate from....its Tshushima all over again in my opinion.

If the USN suffers a heavy one sided defeat and the Japanese offer reasonable terms, I see it as possible for the hJapanese to achieve their goal of a free unfettered hand in east asia as a result of peace negotiations. Its still a long shot, and as you say most unlikely for the Japanese to pursue, but an interesting what if just the same

The Japanese had, by 1939:

6 aircraft carriers: The Soryu and Hiryu, Ryujo and Kaga, Akagi and Hosho. Also often overlooked, are the IJA aircraft transports used to ferry Army aircraft.

They had 10 battleships, 16 Heavy Cruisers, 17 Light Cruisers, 113 Destroyers, a decent amount of submarines and other surface vessels.

Thier merchant ships numbered over 2,000, accounting for well over 5 million tons.

I think the Japanese were pretty well equipped for bringing a fight to the U.S., especially in light of the fact that the Japanese had battle tested crews and equipment by 1939, and the U.S. didn't and was, quite honestly, not prepared for any kind of fight at that point in time...

Only four were fleet carriers capable of 30+ knots. The others were suitable only for escort duties.

Just WTF are your IJN carriers going to do against the Lexington/Saratoga/Yorktown/Enterprise?

You think the USN is just going to roll over and play dead??????????????????????????

Come on you genius's that think that the Japanese could invade Hawaii, let alone the US mainland. What are your D+15, D+30, D+60, D+90, D+120, D+180 D+360 plans? These dates are what the allied SHAEF planners looked at for the ETO/MTO operations plan for 1944/1945. It is not unreasonable for the same type of issues to be put before the IJN/IJA .... what are you going to do???????????????

Are you telling me the the Japanese are going to execute the most sophisticates amphibious invasions in history without the proper amphib assets, without any type of doctrine and without any type of logistic support???????

Are you telling me that an invasion force of the magnitude you are proposing is going to sail several thousand miles without detection? Rightttttttt ..... theyre never going to be seen ...... theyre invisible.

Come on .... think about it .... remember those D-day + x dates ..... think you might want to factor the US manpower and industrial mobilization dates into the equation???

Sys, I'm playing Devil's advocate here, working out a scenario...

In all honesty, if the Japanese fleet can steam halfway across the Pacific and kick our ass on 7 December 1941, what makes anyone consider that they couldn't put something together a couple years earlier when the clouds of war weren't as obvious on the horizon? Also, the Japanese would have had the luxury of time on thier side to complete a thorough plan with followup plus thier codes hadn't been broken at this point in time, either.

As of 1939, the U.S. Navy had 5 aircraft carriers, 15 battleships, 18 heavy cruisers and 19 light cruisers, etc...not all of these assets were in the Pacific, and most hadn't been placed on a heightened state of readiness since the war in Europe hadn't taken off yet.

Keep in mind that the U.S. lost 6 carriers during the war, 5 of which were lost in 1942, during the height of Japanese naval power. (this does not include escort carriers)

The P-39 wasn't ready for action yet, the P-40 was just getting under way in production and the B-17B was the current model in production. That meant that the front line fighters the Army had, was the P-36 and early P-40...the Navy had the F2 Buffalo and the F4F in it's early form, which was still undergoing development.

I think that the United States military would NOT roll over, but given the events and thier indication of a poor war-readiness that unfolded in 1941, such as Pearl Harbor, the Phillipines and other assets that came under initial attack, it shows that this would have been a real uphill fight.

Its a difficult operation, but the question here arose as a result of it being assumed the Japanese would react in a certain way and attack specific targets. Thats about as dangerous as it gets, because if there was one thing the japanese demonstrated pre december '41, was that they were unpredictable. Yammamoto basically intimated that if Japan wanted to take on the Americans, they had better be prepared to fight all the way to Pennsylvania Avenue. This hypothetical builds on that summation.

Now you mentioned what would the USN be doing whilst this was going on. If the Japanese undertook a smash and grab, occupying all the ports on the west coast, then the ability of the US to react becomes very difficult. You are trying to compare the historical situation faced by Japan and the very real limits placed on her strategic choices as a result of shipping limits. All very true, but fails to take into account that the Japanese were attempting to support two supply lines and not one. The first was the raw materials merchant shipping lanes from the Indies to Japan. The second was the munitions lines from Japan to the garrisons. Now, if there was just one front for the japanese to worry about, then they have the resources of their entire shipping fleet at their disposal. If this attack takes place prior to the violation of Dutch and Norwegian neutrality, they also have access to nearly 7 million tons of neutral shipping to continue to bring in non military cargoes like oil and rice from the Indies to Japan. Shipping is not going to be a constraint under those circumstances. The Japanese can call upon almost their entire merchant marine for a single front war. They are simply not going to have anything like the logistics problems they had historically. The Americans do not have an effective sub fleet in 1939, so losses to Japanese shipping are going to be minimal

You mention that the USN would not sit idly by while their country was invaded, and I agree, they would likely implement some variation of their war plan Orange, and the Japanese would implement a variation of their reaction to it. In 1941, the USN had considered a War Plan Orange style reaction to the invasion to the Phillipinnes, and shelved it....they knew that they would more than likley lose most of their fleet if they tried. In 1943 -4 they did finally, and successfully implement a war plan orange variant, but with massive reinforcement, fast battleships, Hellcat fighters, Essex class carriers, Fletcher class destroyers, Gato class subs, to name just a few of the technological advantage they needed to bring into effect enmasse. In 1939 they had none of those things, and would suffer from no effective bases for thousands of miles and no effective fleet train. It would have been a disaster waiting to happen.

You suggest that a similar amount of planning would be required to invade the continental US in 1939, as was required in Normandy/France in 1944. This however fails to take into account the differnt opposition levels and experience of the respective defenders. In 1944, the Germans were still the most well trained army in the world, and could call on an army of 39 Divisions. The defenders had had 4 years to entrench and improve their positions, and potentially could call on the resources of several hundred further divisions. Small wonder that the Allies had to go to extraordinary lengths to plan for this invasion.

By comparison, in 1939, the west coast of the US might be defended by the best part of a division, with perhaps another two divisions at some notice. It would have been critical to withold some of that 100000 man army for further exansion and training. There were no tanks, pitifully few AT weapons and no combat experience. Against that we have 10 Divisions of battle hardened veterans, backed by at least 500 tanks, and oodles of fight. Why would it be necessary to put the same effort into what would essentially be an unopposed landing(s) to one where an inexperienced army was landing into the teeth of enemy opposition. I just dont see that there is any comparison.

One might argue that the Americans would get some advance warning, but judging by their efforts pre-Pearl harbour, I dont see this as doing them a hell of a lot of good. The more US resources that get sucked into this maelstrom the better actually.....the best option in my opinion would be to retreat to the Rockies and hold out in the mountains until the country could mobilze itself. A forward defence, or worse a naval defence is about the worst thing the US could elect to do in these circumstances

That's about what I thought. It would take time for what was then a neutral nation to mobilize and make some kind of concerted effort. I think it would be imperative for the U.S. to hold the mountains at any rate. In the mean time the European theater would be just picking up steam I think. England may have a bigger fight due to a lack of extra materials from the U.S..

As I recall, Germany had an alliance with Japan as well though I don't know the date of that alliance nor how that may play out.

One factor being ignored in this discussion about a fantasy involving an invasion of the continental US by the Japanese in 1939 is that the the regular army of the US was indeed small and poorly equipped in that time period. However, the reserve or national guard forces, though also poorly equipped, were fairly numerous and would constitute a serious opponent for any invasion force, especially one as poorly equipped,( from a modern mechanised point of view,) as the Japanese army would have been. There were also, in 1939, many veterans of WW1 in the US which could have been armed and immediately gone into combat. Another point is that in 1939, just like today, the civilian population of the US was probably more heavily armed than any other population of a large modern country in the world. Not only were there guns in almost every household but ammunition was available in every hardware and corner grocery store in every small town in America. Any Japanese army would have been essentially foot soldiers with little if any mechanised or armor capability. Essentially, an invasion and the subsequent occupation of any part of the US would have not been that much different from the American Revolution except for the repeating rifles and automatic weapons. Another factor which would have played a major role in the attitude and morale of the defending forces would have been the racial overtones. The Japanese were considered to be subhumans by most Americans. An attack by these "primitive barbarians" would have unleashed all the racist characteristics which underlie the American psyche. If the Japanese could be brutal and uncivilised during WW2, the Anglo American could be equally or even more so in 1939. The Japanese could never have landed and resupplied a large enough force to have had any chance of conquering and subduing even a portion of the US. Trying to do so would have been the same as sentencing the force to death.

Traditionally it was the communists who organised the best resistance movements. This happened in Yugoslavia, the Soviet Union, and China most prominanetly, but in fact in every country that resistance movements were set up, it was the communisists who played the biggest part in the successful prosecution of the resistance war. Even in western europe, where SOE played such a crucial role in arming and assisting the French resistance, it was the communists that provided the organizational skills to rally and organize the civil population into resisting the occupying forces. The reasons for this are varied, but mostly due to the fact that from a very early point in their existence, the communists had learned to act and organise civil resistance even before the war had begun. They had the clandestine organizations, the secret methods of communication and the like. None of the other resistance movements came close to being effective in any sense....even in Poland it was the communists who provided a great deal of organising ability to the Polish resistance, though they were not actually in control. And as far as I am aware, the communist movement in the US was virtually nonexistent in 1939

The other thing about resistance movements is that they generally take a lot of time to organise before they have any real effect. Titos partisans were not any sort of resistance until well into 1943 and they had access to all manner of weapons, including tanks and artillery. The Soviet resistance movements were very similar....though resistance was promulgated for all bypassed red army formations, and a good deal of anti-german sentiment manifested within 3 months of the invasion, it was not until the latter part of 1942 that the Soviet partisans began to have any real effect. The french resistance was the same.

Whilst American sentiment might lend itself to civil disobedience, they lacked the clandestine orhganizational skills to have any reall effect in the short term. Perhaps after two years of the war an effective resistance may have occurred, but in terms of an immediate and spontaneous resistance movement, it would have been similar to all the others....inneffective until it was too late.

The great problem for the Americans would not be manpower....thats relatively easy to overcome in such a large country as the US. But delivering coherent and trained formations from that mass of humanity is the real problem, and the number one problem facing the US army in WWII. To illustrate the point, the US began to mobilize in the latter part of 1940....full rearmament began before June 1941, and continuing all the way through 1942. At the end of 1942, the US had no more than five divisions world wide ready for offensive operations, with perhaps another 5 capable of defensive operations...by the time of Normandy this figure had risen to about about 40 Divs in total....the expansion of the American army was a painfully slow process because of the small size of the training cadre. In this scenario, the training cadre would be even smaller,, because at least a portion of the army would be needed to fight in the front lines.

Whilst the Japanese army is considered inferior in the west, it fought in fact virtually unsupplied from 1944 on, and in places like Guadacanal, even earlier. When it was supplied it demonstrated time and again just how dangerous it could be. These guys fought Zhukovs siberians (who in turn defeated Germany's finest) in 1939, and whilst defeated, demonstrated their proficiency nevertheless. Against untrained troops it demonstrated it could defeat them with ease. And this is precisely what would happen in an invasion 39 scenario. The US would be forced to commit untrained, poorly armed formations to battle, that would fall apart just like the Soviets (in 1941) , the Chinese and the filipino troops did when they were committed in an untrained state. The US forces would have been steamrolled if they tried to fight in anything but the most favourable defensive positions. Any attempt at offensive action for the first two years would more than likley have ended in a debacle, and given the US military's penchant for elan and the attack at all costs, this seems a very likley outcome to me. Encirclements and pockets in the hundreds of thousands to rival the east front are not out of the question

IN 1942 Australia was faced with the prospect of an invasion. By then it had the best part of 10 Divisions deployed, with a total manpower strength approaching 700000 men. To that force was added a further two divisions of US Infantry. The Japanese believed they would need a force of ten divisions and a million tons of shipping to conquer Australia. The armed forces at the Austrlian governments disposal had had around two years of miliatary training, but were inadequately armed. Despite this they were far better from a readiness point of view than the US would have been in 1939. And yet the Australian army agreed with the Japanese assessment....if the Japanese had invaded, the Australians did not think they could stop them

What needs to be understood about the US in 1939 was that it was a much more rural country than it is today. These rural areas were loaded with hunters and people in agribusiness who were used to using guns for extermination of varmints and predators and for recreation. The problem the Japanese would face is that they would only have a very small force that could be landed and supplied. It would not be a resistance movement they would face or an insurrection because they would not be allowed to conquer much territory but the armed citizen would constitute a militia and they, along with reserve, national guard and regular troops would simply overwhelm the Japanese force. See Bunker Hill and Concord. A Japanese invasion of the west coast would be akin to a mouse crawling up an elephant's leg with rape on his mind.

Nice analogy about the elephant than the mouse. Unfortunately, you are making assumptions that I simply cannot fathom. You believe that the japanese would be landing with a limited force, and would be overwhelmed by large forces of irregular troops, drawn from the back woods country of the US. In fact the Japanese would be invading with an initial invasion wave of between 5 and 10 division, just in the initial assault waves, initially to capture the port and airfield facilities on the west coast, and then to move rapidly as possible west. The initial assault waves would outnumber any defenders by at least twenty to one, and behind that would be following another 25 Divs to continue the advance. Against this would be a regular force of perhaps 2 Divs, backed up by an unlknown irregular force, which you believe would organize, arm and train itself immediately, and do so managing to avoid all the failures that are the trademark of untrained militias, simply because they are American. Give me a break. These formations in open warfare, if they could be thrown together in the 3-6 months of a campaign like this, would be absolutely mown down eith only their patriotism and elan to rely on.

You are grossly underestimating the effectiveness of the Japanese soldier in these conditions. They managed to defeat Chinese forces whilst outnumbered at least 10-1, they overran untrained, but organized western armies in the far east with ease, in this scenario they would have the full resources of their China Expeditionary forces, with a massive advantage in numbers quality experioence, equipment and supply, yet you believe they are going to be stopped by farmers armed with privately owned rifles, based on the premise that they could do it during the American civil war.....sorry, I just dont buy it, and to take your analogy just a little further, think in fact it would be the elephant trying to rape the mouse to be honest.

In the finish, all that you say would have an effect - eventually. The US country boys would make easily trained and effective soldiers. The Japanese would run into supply and resistance difficulties. They would ultimately be defeated, but there would be a terrible cost, and the objective in my mind would not be to subjugate the US, but to seeks terms from them ina variation to the "strike south" policy in Japan

The Japanese desperately needed the oil resources of SE Asia before they committed any forces to a wild goose chase in Hawaii, let alone the mainland US.

The USN in 1939 was capable of inflicting blows upon the Japanese off of Hawaii, and to think the IJN is not going to not suffer any ship losses is rubbish. And any IJN ship thats damaged off of Hawaii meant a very long sail back to any port capable of repairing it.

Now what about that fantasy invasion of the US mainland? You think the Japanese invasion fleet is going to steam at 30 knots to the mainland? Try 5 - 10 knots. Think its all going to be done with zero detection? LOL!!!! Do the Japanese have enough tanker assets to supply the fleet? Nope. Ever consider that the cycle time for a cargo ship to go from Tokyo to San Fran and then back is something like 45 days? Think of the number of merchant vessels that will be doing absolutely nothing for multiple weeks at a time. Now think about how the US will be mobilizing its industrial base at 15 day intervals with multiple rail lines supporting its logistics lines.

Then factor in the geography of the west coast. Rugged mountain ranges along the coast followed by even more rugged mountains followed by deserts and then more rugged mountain ranges. And that doesn't even count several hundred miles of prairie and steppes before they would even be within range of the industrial centers of the midwest. And this is going to be done by a few divisions of light infantry? LOL!!!!!

Now about Hawaii ... think of this. Oahu is big enough for the defenders to maneuver within interior lines of communications. Plus its small enough to defend in depth, with naval gunfire support from Pearl. That's recipe for a tough nut to be cracked by a Japanese force who never had the training, eqmt and doctrine to land a multi-division force on a defended beach, manned by soldiers who had to fight with their backs to the wall.

Allied experiences off of Salerno in late 1943 were still marked by poor planning and execution. And that was with two large invasions already under their belt. Do you think the IJN is going to do everything flawlessly in 1939 with no experience? LOL!!!!!

The Normandy planners could only land five divisions with a invasion distance of less than 100 miles. And even then, the allies could only land an additional division every day. As more troops went ashore, more and more shipping was required for supplies. How are the Japanese going to do anything to the contrary? Pull off the largest invasion in history, one that was equal to, or larger than Olympic/Coronet?

As for the US forces arrayed against them, there was plenty of WW1 heavy weapons available. Including large gun batteries that covered major ports and installations. And if they land outside of these guns, they still have to march through mountains with clearly defined choke points that could hold them for quite some time. Think Anzio and Monte Cassino. A couple of MG's holding up battalions.

And I will repeat this: US manpower and industrial mobilization. More and more and more and more equipped troops as the weeks pass. You think in "days". I think in months.