What if...the Japanese had landed troops in Hawai'i immediately after bombing Pearl?

Gents,

Along with the Sealion Invasion, this Hawaii topic has generated much discussion over the 68 years since Dec.7'41.

Once he realized the success of the historical air attacks on Pearl Harbor, Admiral Yamamoto expressed his own disappointment at having missed an opportunity to invade those islands and immediately ordered his staff to begin planning. A process which eventually led to the Japanese disaster at Midway.

I have long been convinced of "the Japanese might have pulled it off (but ONLY on Dec.7'41)" side of the debate but I hasten to add that the American invention and use of the A-bomb would still likely have been the end of the Pacific War. At least, I hope so.

Just a couple of years later than the historical 1945.

It is a long and tortured road but if you wish I can show you how and where the Japanese might have found the tankers, the freighters and the troops needed to invade Oahu on Dec.7'41, without having to abandon their first war priority, the capture of the Netherlands East Indies (NEI) oil sources. Nothing else was as important to the soon to be fuel starved Japanese Empire at that time.

However, in my opinion they didn't devote nearly enough thought to the subject of how to keep that oil after they had captured it, as they should have.

I believe that capturing Hawaii MIGHT have accomplished that for the Japanese, or at least that the Japanese might have convinced themselves of it before Dec.7'41, even if the American public did not later decide to "forgive and forget" an even more dastardly sneak invasion there.

A major re-vamping of Japan's entire Pacific War strategy would have been required, under Yamamoto's guidance, but would have required no imaginary warships nor invented troops. The Japanese HAD the military resources needed but just didn't use them as I'll suggest below.

In very brief summary form, the Alternative Timeline (ATL) Japanese would have had to decide to postpone their Original Timeline (OTL) invasions of Luzon, Guam, Wake and the Gilbert Islands so that the troops and shipping historically used there could be used to secretly carry Imperial Japanese Army (IJA) and Japanese Special Naval Landing Force (JSNLF) troops to Oahu. About 2.5 divisions worth.

I can show the availablity of 1,680,000 tons of shipping and an additional 41 Japanese tankers for this "instead of" invasion scenario.

Note however that the OTL Japanese landings on the Philippine island of Mindanao would in fact be slightly strengthened and advanced in schedule so that Japanese land based air (LBA) flotillas could operate from captured American airfields near Davao there in order to isolate and air blockade the American forces still holding Luzon. As per the OTL, Mindanao LBA would co-ordinate with Formosa LBA to suppress the American warplanes and USN submarines/tenders based in and around Manila. Once those American air and sea forces were driven back to Australia or destroyed, Luzon would just become a very large and self-feeding prison camp, already well isolated behind the ATL Japanese frontlines. NO threat at all to the yet to be established sea lines of communucation (SLOC) between Japan and the NEI's oil.

The Japanese would need several more months to both capture and repair the NEI's oil installations (as per the OTL) and during that "slack time" there were many Japanese shipping resources laying idled that COULD have been more boldly used for a Hawaiian invasion instead.

I would point out that Oahu WAS very heavily defended by two Divisions of the US Army, the 24th Infantry and 25th Infantry. Only by the delivery of a surprise atttack greater that the OTL Dec.7'41 raid could the Japanese hope to seize that island fortress and later, the only weakly held other Hawaiian Islands. Details to follow should you find the ATL Japanese strategic premise detailed below to be acceptable.

There is indeed a good arguement that once captured, the Japanese would have had a difficult time in supplying Hawaii over the long term. In the short term however the Hawaiin Islands did have food supplies sufficient for 90 days for all souls (both invader and invaded) not counting the nutritionally empty sugarcane and pineapple crops growing there, nor fish from the seas surrounding (400+ fishing sampans operated out of Hawaiian waters mostly to supply the pre-war export market to the US west coast).

Considering the historical Japanese record of NOT feeding prisoners more than staravtion diets while working them to death, I estimate that the Hawaiian Islands would be fed for about 9 months after capture WITHOUT the Japanese importing any food at all, if necesary. Each and every Japanese ship that did arrive there with food however would leave with a well publicized human cargo intended to both shield that vessel from USN submarine attack and to reduce the number of mouths that needed to be fed there every week.

This would bring them to the time when Japanese successes in repairing the NEI oilfiels would mean that the tankers used for the Hawaiian Operation would be REQUIRED elsewhere, instead. About a year later.

That year would NOT have been wasted by my ATL Japanese.

Provided that their invasion of Hawaii had withstood the inevitable USN Atlantic Fleet counter-attack via the Panama Canal, round about the end of January 1942, that is. Again, details to follow if the discussion goes on that long ...

Had that string of defeats actualy come about, the American West Coast would have been virtualy defenseless and Lend/Lease would have been politically impossible to continue. Both the UK and Russia would have been at the mercy of German forces and Hitler's whims as the Americans rebuilt their west coast defenses.

Yamamoto's "war winning" plan (and not that I think that it would have been guaranteed to have worked) was to then offer to trade the Hawaiian Islands and 500,000 American hostages (including those from the Phillipinies, Guam, Wake, Midway etc) for a comprehensive Pacific wide ceasefire agreement and American recognition of the new expanded boundaries of the Japanese Empire.

As far as I can think, the ONLY possible (if still unlikely) way that the Japanese Empire might NOT have ended with atomic fireballs.

 

I'll buy that

 

After 1 March 1942, the Japanese military leadership decided their war plans had been too conservative and pessimistic. They had expected to suffer a loss of one-fourth of all their forces in their offensives to date. In fact, the losses had been negligible. There offensives had been successful beyond there wildest expectations. Accordingly, Tojo and Yamamoto worked out a compromise agreement to extend the strategic objectives of the war plans to encompass an even larger area for the Greater East Asia Co-Prosperity Sphere. (Manchester 293-294).

Yamamoto's task was to advance Japan's control of the Pacific onwards to Alaska and Midway..... Yamamoto was to advance from the Aleutian Islands and move down the coast of Alaska through Dutch Harbor and Juneau towards Washington, capture Hawaii, and use Alaska and Hawaii as bases for further raids upon the Pacific Coast from British Columbia to California.

(Manchester 293-294; Garfield, 4-8,44, Layton, 383)

Japanese air bases in Alaska would be within three hours bombing distance of the Boeing aircraft plant and Bremerton Naval Shipyard in the Seattle, Washington region (Garfield, 16) At the time 60-70% of the total US Military aircraft production was here on the West Coast within 10-100 miles of the coastline.

BTW Japanese submarine-launched scouting type aircraft were sent over Seattle(Craven, 277-286)

References:

Manchester William: American Caesar: Douglas MacArthur 1880-1964. Boston, Mass.: Little, Brown and Co.; 1978. pages 293-294

Garfield Brian: The Thousand-Mile War: World War II In Alaska and the Aleutians, 1st edition. New York; Ballantine; 1969. pages 4-8,16 & 44

Layton Edwen: And I was There, Pearl Harbor and Midway-Breaking the Secrets, page 383

Craven Frank Wesley & Cate James Lea: The Army Air Forces in World War II, Vol. 1, pages 277-286

 

Jagdtiger1, in your posting #7 you wrote,

The Malaya/Thailand invasions continue on as per the OTL Japanese plans.

If you were to do some google searching you would find that the OTL Japanese had on several occassions put 2 divisions ashore at a time on the Chinese coast between 1932 and 1940. It is not widely known but as the Pacific War got going, the Japanese were the world's leaders in amphibious landing techniques and technology. Their 3 sizes of daihatsu beach landing barges had no rival anywhere and their amphibious landing crews had trained for years in China combat. Hence their unbroken (save for the Wake Island #1 setback) string of Pacific Island invasion victories over the first 6 months of the Pacific War. It wasn't just luck.

One very important point to note though, is that the OTL Japanese specialised in "landing where the enemy wasn't". Unless there was NO other choise (such at Kota Bharu on the north end of Malaya, Wake Island or Corregidor). More specifically, they chose to AVOID prepared and manned defended beaches in favour of landing AT NIGHT on undefended beaches, a few miles further up or down the coast before moving inland to hook around behind the then surprised beach defenders by dawn.

They did train and regularly used light naval units such as minesweepers and the invasion convoy escorting destroyer group (often led by a light cruiser) for the close range direct fire "over the beach" naval gunfire support mission. Neither the IJN's 1941 heavy cruisers nor their battleships were trained for close support "over the beach" gunfire that was developed by the USN several years later during their numerous Mediterranean and Pacific Island landings. Never was IJN gunfire able to "peel bunkers off the beach" as were the USN's battleships able to do at Normandy and Iwo Jima. Both the IJA and the IJN's JSNLF troops prefered undefended beaches suitable for barge landings as identified by extensive pre-war scouting. In the case of Oahu, Yoshikawa of Japan's Honolulu Consulate was the man who would have performed that intell. gathering function.

Certainly in the case of Oahu, any Japanese invasion would by necessity HAVE to be a night landing, in complete secrecy, before dawn on Dec.7'41. If the American 24th and 25th Infantry Divisions were pre-warned and allowed sufficient time to deploy to their assigned beaches, and to dig in there. then no Japanese invasion would be likely to survive the attempt. My ATL Japanese invaders MUST get ashore on Oahu "where the defenders aren't" or they will certainly be destroyed in the surf by prepared American firepower.

Only the particular set of truely bizarre Oahu circumstances observed and regularly reported to Tokyo (via coded commercial telegram) by Yoshikawa would allow the success of an ATL Japanese invasion attempt there. In order to explain those circumstances, much reference will be made to Gordon Prange's thick Pearl Harbor tome, "At Dawn We Slept" so it would be best if you were to have access to a copy in order to follow along.

 

How in the world can the Japanese get that close to Hawaii without being seen? Given their lack of experiance in invasions how are they going to possibly get major forces ashore before the US can react? What kind of support do you think they could assign to this invasion?

 

Lets just pretend they had some capability.

 

lwd, thanks for the reply.

I see that you have chosen to cut to the heart of the matter without wasting time on all of that strategic "stuff".

I like you already.

On the assumption that Yamamoto is actually given "free reign" command of the IJN's Hawaiian strikeforce AND troop support from the IJA ...

Point by point ...

How in the world can the Japanese get that close to Hawaii without being seen?

Exactly the same way as they did historically, with some additional daring.

Please emember that night on Oahu is 12.5 hours long at that time of year with sunrise at 0606 and sunset at 1735.

Prange's "At Dawn We Slept" reports that three Washington approved Japanese repatriation passenger liners passed thru Oahu's Honolulu Harbor in the two months prior to Dec.7'41. Japanese agents on board reported to Tokyo that United States Army Air Force (USAAF) scout planes were first seen 200 miles offshore from Oahu and that the first USAAF attack bombers only "buzzed" the cargo-liners at 100 miles offshore. Yoshikawa reported as late as 1800 on Dec.6'41 that the USN was still NOT flying any long ranged seaplane searches out of Oahu. Thus the OTL Japanese assumed that they could safely approach to within 200 miles
of Oahu WITHOUT being spotted by American air recon at dawn. It was NOT just a random pick that saw the OTL Nagumo launch his historical air strikes from 230 mile NE of Pearl Harbor. The OTL Japanese chose that distance based on the known US air recon radius of 200 miles.

My ATL Japanese would do the same by crossing that 200 mile line at dusk on Dec.6'41. A run in at 20+ knots for 12.5 hours gives them a travel distance of 250+ miles before sunrise. Up to 312 if they bump up to 25 knots as most IJN warships could easily do. They didn't need either.

Save just off of the Pearl Harbor entrance channel (the gateguard destroyer USS Ward and others), there was no USN patrol around Oahu at all. None. And Yoshikawa, who regularly rented civilian aircraft for "sight seeing" trips all over Oahu, would have easily reported such to Tokyo.

Who was going to see my ATL Japanese invaders rushing in thru the peacetime Satuday "liberty night" darkness ?

Despite Washington's alerts, no one on Oahu was even looking.

Since my ATL Japanese are not blessed with hindisght, I include for them an additional distraction JUST IN CASE an American or two on Oahu was not "asleep at the wheel" as most there were on Dec.6-7'41.

Prange's book also reports that a 4th OTL Japanese fast repatriatin cargo-liner, the big 17,500 ton 20 knot+ Tatuta (also spelled Tatsuta) Maru (TM) was Washington approved for yet another Honolulu port call on Dec.9'41 while on her way between Yokahama and San Francisco. In reality hers was a deliberate Japanese deception mission designed to lull Oahu's defenders into a false sense of security. What nation would send a passenger ship full of civilians to an island that they palnned to attack ?? Historically she went radio silent and turned back to Japan at 0005 on Dec.7'41.

In my ATL she would have been scheduled instead for an 0530 Dec.7'41 arrival at Honolulu and would have led (by 60 or so miles) my ATL Japanese strikeforce across the northern Pacific, sending coded radio messages for her civilian passengers, all the way. A fast moving radio beacon that the American radio direction finding (RDF) types could easily follow all the way from Japan to Hawaii. Never once dreaming that a powerful Hawaii invasion force followed close behind that now scouting cargo-liner.

Given their lack of experiance in invasions how are they going to possibly get major forces ashore before the US can react?

As I just previously posted, the OTL Japanese had been doing 2 division landings on the Chinese coast since 1932 so they were NOT at all inexperienced. Against undefended beaches anyway.

My ATL 1st landing wave (1LW) would be comprised of only 9 Japanese fast troop-carrying vessels hauling some 11,500 lightly equipped troops.

Three big fast cargo liners would each host a regiment (of 3,400 men) of Japan's 7th Infantry Division. That formerly crack division had been badly mauled by Soviet firepower at the Nomonham battles in 1939 but had been resting/refitting/training in reserve status in Japan ever since. They were EAGER to restore their sullied battle honor and had time to train for both beach landings and jungle/mountain combat on Oahu.

On two of the three NYK Lines cargo-liners, their regular lifeboats would have been replaced with three sizes of daihatsu landing barges (30 men, 70 men or a light tank, 125 men or a medium tank) that could be lowered (already fully loaded) over the liner's side by lifeboat davits and their cargo booms for fast troop unloading. Only two full round trips to the beach would be required by each daihatsu to empty the IJA troops off of each liner. More trips for the regiment's heavy equipment to be sure but at least the IJA's light infantry would already be safe from American air attack, coastal artillery fire or naval gunfire, after sunrise.

Also along would be 6 OTL converted ex-DDs, called "patrol boats" by the OTL Japanese, 4 of which would carry 2 daihatsu landing barges and 250 JSNLF troops each and 2 smaller versions each with 1 daihatsu landing barge and 125 JSNLF troops aboard. These would be the "distraction troops" (DTs) to be landed on several of Oahu's shorelines to cause havoc and confusion for General Short's US Artmy defenders. Which shoreline would the surprised Sunday morning peacetime American defenders rush to when ALL were reporting dawn landings and combat ??

Another Japanese infantry division would land on the following (Dec.7-8'41) night, provided that safe landing areas had already been secured by the 1LW.

Thus, my scenario includes a distraction or two designed to keep Oahu's defenders busy and blinded, as follows ...

What kind of support do you think they could assign to this invasion?

I had in mind 8 of the 10 battleships of the Combined Fleet (CF).

Plus escorts to include 1 CV(L) loaded only with Zeros for CAP duties overhead.

Go big or stay home, I always say.

The other two BBs (the older, slower ones) are still assigned in distant support of their Southern Operation, as two were in the OTL.

Their main gun ammo loads would be roughly 75% bombardment HE and 25% anti-warship AP just in case the USN's Pacific Fleet somehow received an advanced warning and sortied for a "Decisive Battle" at sea somewhere off of Hawaii. Or in case the KB's warplanes were not able to complete their anti-warship target assignments within Pearl Harbor. The CF battleships had a 4 knot fleet speed advantage over the older USN battleline (with 30 IJN submarines equipped with WORKING torpedos in close support) so that the CF could stay just out of range as their submarines and the KB's warplanes whittled away at the American Fleet's strength.

Bold I know but it is better to control the time and place of the "Decisive Battle" yourself than to allow your enemy to do so. As per that Mahan source that was just recently posted upthread here.

I'd also like to include the just built Yamato as IJN battleship #9 but to do so I'll need general agreement here that she might have been completed and her crew trained a few months earlier than historically by the shifting of most of her sister Musashi's construction crews over to work on her, in secret. Considering that the OTL Americans still didn't know the real size of those 18.1" main guns in mid-1944, I don't think an earlier Yamato completion to be too much of a "stretch" but your/others opinins may differ. I hope that we can "talk about it". My ATL scenario is NOT dependent on Yamato's presence off of Oahu's shores but she sure would make things easier for my ATL Japanese if her big guns were there.

Yes, I know that 4 additional civilian tanker to fleet oiler (capable of underway refueling - UWR) conversions ( 8 OTL + 4 ATL = 12 now) will be required to fuel the KB + CF across the northern Pacific. In the OTL there were some 49 available, at least until the NEI's oil was available again.

In the OTL, the Combined Fleet did nothing much save cruise slowly out around the Bonin Islands and then back to the Inland Sea in VERY distant support of Nagumo's Kido Butai (KB) carrier strike force. By using the same deceptive radio broadcasting techniques to "hide" them as were historically used by the Japanese to "hide" the KB during it's journey toward Hawaiian waters, I believe that they would arrive there just as undiscoverd as the KB was, historically.

A regular stream of faked radio traffic could easily be genarated to make the listening American code-breakers believe that the CF's battleships were engaged in thier normal gunnery practise exercises in the Bonins. Thus easily explaining any intell reports of IJN BBs loading more main gun rounds that might have reached American ears.

 

Getting the invasion force you have suggested anywhere near Hawaii without being detected is highly problematic. Let's look at the problems:

1) The transports have to leave well in advance of the fleet or the whole fleet has to travel at the transport speeds. This has a number of implications. One of the most important is it leaves a lot more time for the force to be discovered. It's also a much bigger target as far as observation is concerned.

2) When the battle fleet "dissapears" warning bells are going to be going off all over the place. The longer they are at sea the harder the allies are going to be looking for them.

3) Then there's the problem of fuel usage. Japan does have enough fuel for this op but it's going to require most of their tankers and many of the ships will have to refuel at sea some several times.

4) In addition to their being extra searches everyone is going to be quite a bit more alert. One of the things that helped at PH was that the impression was that sabotage was the main thing they had to worry about. If the Japanese battle fleet has been unaccounted for for weeks that perception is very likely to change.

5) Consider also the code breaking situation. The Japanese naval code had been compromised but they changed it just before the PH op. If they change it according to RL then there's a very good chance some details are derived due to the op getting underway weeks earlier. If on the otherhand they change just before the op starts there is a chance that the US will have broken the new code at least to some extent before the strike and gotten some valuable info that way. The absence of the battle fleet will likely spur efforts in this regard.

As for the Japanese practicing landings in China. How long did it take them to get forces ashore? My understanding is Sakai was amazed at how fast the US was doing it at Gaudacanal. At least in the copy of the Caiden book it is stated he thought that the US was doing this much faster than the Japanese. The practice landings in China would also not have been in heavy surf, in areas with coral reefs, vs land, sea, and air opposition. I'm pretty sure the US had at least a small armored force on Hawaii as well as numerous coastal batteries (covering the likely invasion beaches). I certainly wouldn't want to try a night invasion in this situation and or bring my transports in range of shore batteries.

My impression is that if Yamamoto were given a free hand this is the last thing he would have tried. If he had elected to try it given his (and Japan's) proclivity for overly complex plans that tended to underestimate their opponents doing something stupid I wouldn't give them a very good chance of success.

 

O yea of little faith, would I do that to you ?

You may not like my ATL Hawaiian scenario but when you consider the historical 6 months long Pacific romp of the Japanese all over the Allies, even you would have to admit that the Nipponese had some good capability at both island and amphibious warfare.

They hit fast and they hit hard so as to always keep their opponents off balance. Without allowing time to recover or regroup. "Shoesting" invasions were the norm for them, living off the land until supplies were eventually brought forward, was the expected.

Nine (still onging) years of heavy combat against the Chinese AND the Russians had tightened up the IJA while the peacetime garrison Americans had fought nothing more than tiny "banana republic' police actions with the Marines only, since 1918, some 23 lazy YEARS before.

Until the over-confidence set in, the OTL Japanese had lots of capability, and proved it, time after time, when the Allies couldn't even hold.

 

dabrob you have put quite a lot of thought into this. The only problem is that Japans ground forces and logistics chain were committed to Maylasia, Singapore and the Phillipines.

Bottom line is that if Japan thought that a ground invasion of Hawaii was feasible they would have done it. AND If they thought a ground invasion of the Hawaiian Islands was feasible why didn't they just invade the mainland US?

Bottom line is that Pearl Harbor was beyond their capabilities to support and there is no way Japan could have held the islands. IF they would have invaded and diverterted resources to capturing and defending Hawaii then the war would have been over in late 1943 or early 1944 and Berlin would have gotten "Fatman" and Heidleberg would have gotten "Littleboy".

Logistics.........you have to able to support your forces on the ground

 

Its worse than so far suggested:

First, what other invasion does Japan give up to invade Hawaii? They have limited transport available are were using everything they had in the OTL elsewhere.

Next, the largest invasion the Japanese managed to stage was two reinforced infantry divisions in size. This requires about 100 transport ships to haul. So, that would be the approximate maximum size of the forces the Japanese could land in Hawaii.

Hawaii has some of the heaviest coastal defenses of anywhere in the US. Coastal artillery ranges up to 16" in size and those guns outrange anything the Japanese have. Many are in heavy fortifications as well and largely immune to return fire.

The US has two full infantry divisions on Hawaii, along with supporting troops. The Marines have a regiment I believe along with at least one defense battalion like the one on Wake or Johnson Islands.
Worse, the US still has several hundred aircraft after the initial attacks. In addition, most of the US fleet is still intact and now at sea. The US still has three carriers whose locations are unknown.

Bottom line is that Japan might have tried this if they gave up going for say, Malayia and the Dutch East Indies to free up the necessary shipping and manpower to do it. Then, they would be looking at heavy losses in ships, manpower and, material to take the island. They likely would gain little in usable resources beyond sugar cane and pineapples as between US sabatoge and the general fighting most of the useful infrastructure would be demolished.

So, even if they somehow miraculously won and took Ohau they are now faced with a weakened fleet, no means to regularly supply their troops there, a hostile population, and the eventual defeat and reconquest of the island(s) taken by the US. In addition, the loss of not conqueroring the DEI and Malaysia will cripple their economy at home.

This is just a major losing proposition for the Japanese.

 

lwd, thanks for your quick response,

Getting the invasion force you have suggested anywhere near Hawaii without being detected is highly problematic. Let's look at the problems:

1) The transports have to leave well in advance of the fleet or the whole fleet has to travel at the transport speeds. This has a number of implications.

Historically the KB travelled at 14 knots but averaged only 11 due too refueling needs. My 1LW has 9 ships, each capable of 20+ knots. I see no problem.

One of the most important is it leaves a lot more time for the force to be discovered.

By who (whom ?) ? There was no one out in the northern Pacific at that time of year to see them and in the OTL Nagumo had orders to quickly sink anyone that stumbled across his strikeforce. I see no problem.

It's also a much bigger target as far as observation is concerned.

What difference does size make when there is no one else out there to see them ? I see no problem.

2) When the battle fleet "dissapears" warning bells are going to be going off all over the place. The longer they are at sea the harder the allies are going to be looking for them.

If you would re-read my previuos posting you will see that my ATL Japanese will attempt to make the Allies believe that the CF is engaged in gunnery training in the Bonin Islands. I see no problem.

3) Then there's the problem of fuel usage. Japan does have enough fuel for this op but it's going to require most of their tankers and many of the ships will have to refuel at sea some several times.

My previous posting indicates that 12 instead of 8 tankers would need to be converted, in secret, to UWR capability. I see no problem.

4) In addition to their being extra searches everyone is going to be quite a bit more alert. One of the things that helped at PH was that the impression was that sabotage was the main thing they had to worry about. If the Japanese battle fleet has been unaccounted for for weeks that perception is very likely to change.

Bonin Islands. I see no problem.

5) Consider also the code breaking situation. The Japanese naval code had been compromised but they changed it just before the PH op. If they change it according to RL then there's a very good chance some details are derived due to the op getting underway weeks earlier. If on the otherhand they change just before the op starts there is a chance that the US will have broken the new code at least to some extent before the strike and gotten some valuable info that way.

Historically the Japanese removed transmitter keys and shoved folded paper between the contacts to ensure that there were no accidental KB radio transmissions during the approach to Oahu. My Hawaii invasion force would do the same.

With the added bonus of having the American approved Tatuta Maru scouting out ahead. Any radio signal "leak" from the Hawaii invasion group would just be atributed, by any listening RDF Americans, as yet another TM origin civilian radio message.

The absence of the battle fleet will likely spur efforts in this regard.

Not absent. At gunnery practise in the Bonin Islands.

As for the Japanese practicing landings in China. How long did it take them to get forces ashore? My understanding is Sakai was amazed at how fast the US was doing it at Gaudacanal. At least in the copy of the Caiden book it is stated he thought that the US was doing this much faster than the Japanese.

By the time of Guadalacanal the Americans were using Higgens boats and alligators to bring "everything but the kitchen sink" lavish levels of supply, ashore. OTOH my ATL Japanese invaders would be light infantry on a "shoestring" logistics plan of living off of the land on Oahu.

The practice landings in China would also not have been in heavy surf, in areas with coral reefs, vs land, sea, and air opposition.

They were hardly practise landings. Combat was often entered within a mile or two of the surfline crossed.

Please remember that Oahu's peacetime civilian radfio stations broadcast 6 times a day marine weather forcasts for the benefit of the 400+ Oahu fishing sampan fleet. My ATL Hawaii invasion force would also be listening to those forcasts as they neared Oahu so as to be able to choose landing beaches not hampered by high surf.

I'm pretty sure the US had at least a small armored force on Hawaii as

JUst a single company of 12 early versions of the M5 Stewart light tank, easily stopped by the 6x47mm horse drawn AT guns that were a vital part of a Japanese regiments's TO&E.

well as numerous coastal batteries (covering the likely invasion beaches).

There were indeed lots of Coastal Atrtillery Corps (CAC) shore batteries on Oahu but they were mostly placed to cover Mamala Bay to the SW of Honolulu and the Pearl Harbor entrance channel. The 1940 Americans had budgeted to build shore batteries to cover Kaneohe Bay but by Dec.7'41 none had been yet built.

In addition the US Army defenders of Oahu had several 8" railway guns and a host of 155mm GPF artillery pieces emplaced for shore defence work but they were habitually returned to their inland depots over the weekend. General Short was afraid of sabotage, remember. As I'm sure that you know, Dec.7'41 was a Sunday.

I certainly wouldn't want to try a night invasion in this situation and or bring my transports in range of shore batteries.

Trying it on Oahu at any time other than night would be virtually suicidal.

If given a free hand Yamamoto wouldn't have tried it.

I agree completely since Yamamoto knew that Japan couldn't possibly win a Long War against an industrial giant like the US. He only insisted on hitting Pearl Harbor when it became apparent that his political masters were insisting on a Pacific War with America.

My ATL scenario supposes that he had been given a "free hand" to do his best to force a Short War with the Americans rather than a Long one.

If he had elected to try it given his (and Japan's) proclivity for overly complex plans that tended to underestimate their opponents doing something stupid I wouldn't give them a very good chance of success.

You are certainly entitled to your own opinion but I intend to try to change that here.

 

formerjughead, thanks for your comments,

dabrob you have put quite a lot of thought into this.

More that a few hours of research too.

The only problem is that Japans ground forces and logistics chain were committed to Maylasia, Singapore and the Phillipines.

That is why I suggest that Luzon, Guam, Wake and the Gilberts be left behind to "wither on the vine" well behind new Japanese frontlines.

Bottom line is that if Japan thought that a ground invasion of Hawaii was feasible they would have done it.

True enough but if that is really your "only history is allowed" point of view, why is it that you read or post to a "What IF" discussion board ?

AND If they thought a ground invasion of the Hawaiian Islands was feasible why didn't they just invade the mainland US?

California had lots of oil but was already attached to an industrial giant of a country called America which (at least back then) seemed to like having it around.

Not so much nowadays.

OTOH the NEI was awash with oil, was closer to Japan and had a motherland just taken over by Japan's allie, Germany. The NEIs seem a more rational choise to me. Invading Hawaii (and capturing 500,000 hostages) is just a way of getting peacetable "bargining chips" to convince American to agree to an early ceasefire (before the Essex class carriers arrive) and a short Pacific war.

Bottom line is that Pearl Harbor was beyond their capabilities to support and there is no way Japan could have held the islands.

If you had actually read my previous postings you would know that I do NOT intend that my ATL Japanese will keep Hawaii but rather will try to trade it quickly back to American in exchange for a short Pacific War and ownership of the NEI's oil.

IF they would have invaded and diverterted resources to capturing and defending Hawaii then the war would have been over in late 1943 or early 1944 and Berlin would have gotten "Fatman" and Heidleberg would have gotten "Littleboy".

I disagree but that matters little to the topic of discussion here.

Logistics.........you have to able to support your forces on the ground.

Reading ........ I have already stated that I can free up 1,680,000 tons of Japanes shipping and 49 otherwise idled tankers to provide logistical support for an ATL Japanese short/medium term effort against Hawaii.

 

T. A. Gardner, thanks for stopping in,

With 4,300+ posts you must be one of the "heavy hitters" posting here ?

Its worse than so far suggested:

For the American defenders of Oahu, yes it is. My ATL Oahu invasion plan is nowhere near being fully rolled out yet. Let alone explained in detail.

Much like my income tax situation.

First, what other invasion does Japan give up to invade Hawaii?

As already typed, Luzon, Guam, Wake and the Gilberts.

They have limited transport available are were using everything they had in the OTL elsewhere.

As already typed several times, I can free up 1,680,000 tons of Japanese shipping AND 49 idled tankers for short to medium term use against Hawaii. At least until the NEI's oil starts to flow once again.

Next, the largest invasion the Japanese managed to stage was two reinforced infantry divisions in size.

MIne will be two unreinforced infantry divisions AND all of the heavy artillery that the OTL Japanese historically used on Luzon against Bataan and Corregidor etc.

This requires about 100 transport ships to haul. So, that would be the approximate maximum size of the forces the Japanese could land in Hawaii.

Since I have found that 10,200 fighting men could be moved to Oahu by just 3 big 17,000 ton fast cargo-liners, I don't agree with your total of 100 being required. But then, it really depends on the size and types of the vessels involved doesn't it ?

Hawaii has some of the heaviest coastal defenses of anywhere in the US.

No question. The historical problem was that at night and on weekends, Oahu's CAC defenses were historically mostly blind. I'll explain later.

Coastal artillery ranges up to 16" in size and those guns outrange anything the Japanese have.

True for three CAC batteries only.

The 2x16" guns of Battery Williston, for the 2x12" guns of Battery Closson and for the 2x16" of Battery Hatch.

However it must be pointed out that beyond the horizon fire was possible only in daylight, with the aid of airbourne or mountaintop spotters with both line-of-sight to Japanese targets AND communications with the long range capable CAC batteries. Night or the loss of air superiority to the invading Japanese would partially blind these American "big guns". Should Japanese light infantry take the "high ground" from the stunned and surprised US Army defenders, then the CAC's guns would be largely out of the fight.

Many are in heavy fortifications as well and largely immune to return fire.

Yes and no. In heavy concrete fortifictions largely proof against direct, flat trajectory naval gunfire, certainly.

Since they were not yet casemated and thus were completely open to the sky however, all were extremely vulnerable to KB diveombing and to high angle "plunging fire" from IJN warships recently (1934+) retro-fitted with high angle fire main guns.

Also to be noted was that many of Oahu's CAC pieces were old and of short range. The "disappearing" type mounts were also of very limited traverse and could NOT send shells over Oahu's two mountain chain backbones.

The US has two full infantry divisions on Hawaii, along with supporting troops. The Marines have a regiment I believe along with at least one defense battalion like the one on Wake or Johnson Islands.

I do have an ATL Japanese plan in mind for them but you won't like it.

Have you ever imagined the effect of spotterplane adjusted 16" and 14" battleship HE shells arriving just after dawn on two divisions worth of still sleeping troops tightly clusterd together within a lightly built four storey barracks complex (the Quadrangles) located in the centre of Oahu ? On a base that also contained the vast majority of their vehicle parks, light weapons armouries, artillery parks and chemical weapons stockpiles.

Such would be my ATL solution for just after the 0606 sunrise on the morning of Dec.7'41. Yet another auspicious "rising sun" situation for the Japanese Empire.

With that type of a supposedly peacetime Sunday morning "wakeup call", I'd not expect much US Army resistance at any of the ATL Japanese landing beaches. While it would most certainly NOT be of "precision guided weapon" accuracy, the IJN wold be able to walk 16" and 14" rounds back and forth across that barracks area for just as long as the KB's Zero fighters could protect the slowly circling CF spotter biplanes.

All day long comes to mind.

Firing over the Koolau Mountain range of eastern Oahu from just offshore of Kaneohe Bay, the 8 IJN battleships of the CF would target Schofield Barracks (2), the warplanes parked wingtip-to-wingtip at Wheeler (1) and Hickam Fields (1), Honolulu's Fort SHafter - the HQ of general Short (1) and the Aliamanu Crater Ammunition Depot (1), leaving two uncommitted as "spares" for Yamamoto's use later in the day. Depending on the successes achieved by the (earlier than historical) KB air strikes on Pearl Harbor, they migh also be used to rain AP destruction down on any US warships seen to be seen trying to transit the Pearl Harbor entrance channel. An American blockship or two sunk there would be a good thing for Japan in the short term.

Yamato's 9x18" guns would just make it worse for the Americans.

Worse, the US still has several hundred aircraft after the initial attacks.

But flyable ? Nah. Not after my CF battleships pound their airfields just after dawn too.

IIRC the Americans only had 360 odd to begin with and many of those were obsolete for combat purposes. To say that Oahu "still has several hundred after the initial attacks" is not a true representation of the very limited opposition in the air that my KB's ATL 3rd strike would face.

Yes, there is a portion of my ATL scenario dedicated to a 3rd air strike on Dec.7'41 also. More later.

In addition, most of the US fleet is still intact and now at sea.

How so ? Or is that other Enterprise using those teleporter beams again ?
i do so hate it when Kirk interferes.

The US still has three carriers whose locations are unknown.

From an ATL Japnese PoV, quite true, however I reserve 50 torpedo armed Kates on the KB's 6 carriers from the 3rd strike, just in case one or more "turn up" on the afternoon of Dec.7'41.

Bottom line is that Japan might have tried this if they gave up going for say, Malayia and the Dutch East Indies to free up the necessary shipping and manpower to do it.

I have previously listed Luzon, Guam, Wake and the Gilberts instead, along with the use of 7th Infantry Division reserve troops from the Japanese Home Islands.

Then, they would be looking at heavy losses in ships, manpower and, material to take the island.

War just sucks doesn't it ?

I note once again that the OTL Japanese walked all over the Allies for 6 months of the Pacific War without taking the level of losses that you suggest here.

They likely would gain little in usable resources beyond sugar cane and pineapples as between US sabatoge and the general fighting most of the useful infrastructure would be demolished.

I have never claimed otherwise but do you really not see the potentails ?

Hawaii is not to be invaded for the resources that are locted there but rather to deny it's use to the United States:

Without Hawaii's runways, no US warplane has the range to fly trans-Pacific to reinforce Allied holdings closer to Japan.

Without Pearl Harbor, American submarines will burn 5,000 miles more of their fuel just to reach Japanese SLOC lanes, thus shortening their "on station" durations and results.

Without immediate access to the PH or Honolulu fuel stockpiles, the USS Enterprise and her escort group runs dry at about 2300 on Dec.8'41. The nearest American UWR capable fleet oiler is the slow USS Neches then plodding along at 9 knots towards Oahu, some 1,200 miles to the NE. The only real question is, do IJN submarines or KB warplanes find her drifting on Dec.9'41, first ? If not ordered by Adm. Kimmel to attack the KB or CF, the Lexington TF and her 17 obsolete Buffalo fighters can probably reach the Neches for fuel and thus survive to fight again on another day.

The loss of the UWR capable fleet oilers USS Neosho and USS Ramapo within PH furtyher cripples ALL of the USN's Pacific operations for several months, until replacements can be brought in from the USN's Atlantic Fleet via the Panama Canal. Some Pacific Fleet refugees from PH who otherwise escape are caught drifting, also out of fuel, before they can reach the safety of US West Coast ports some 2,400 miles away.

The 20,000 or so sailors of the USN's Pacific Fleet who historically formed the cadre training crews of the eargerly waited new US warship construction classes, now won't. Those new Essex class carriers will now take MUCH longer to get ready for action against the Japanese Empire.

Instead, they are drowned in naval combat off of Hawaii or are being worked to death inside of Japanese work camps on the Hawaiian Islands. Those of higher rank are shipped back to Japan proper for none too gentle "questioning" while those with family also captured on Oahu face an entirely different form of hell on earth. Either work (and hard) for your Japanese conquorers or watch as your family menbers ar used for IJA bayonet practise, one by one.

A captured Hawaii means that examples of the latest US warplanes and weaponry are available, with manuals, spares and trained mechanics at hand to fully explain their secrets to Japan's technical experts. Who woun't take kindly to silence or lies when they have asked a question.

Ditto for America's latest radio and radar secrets. Japan's war fighting ability takes HUGE leaps forward.

Ditto as the Japanese explore the ruins of the radio intercept station HYPO found in the basement of Kimmel's Pacific Fleet HQ. Suddenly Japan KNOWS that it's codes have long been broken and a HUGE American advantage disappears. Or, are the Japanese smart enough to use the discovery to feed the Americans with carefully crafted "disinformation" messages to be used in setting up their own traps for surviving USN warships ? Such techniques could certainly enable the ATL Japanese to entice a counter-attacking US Atlantic Fleet into a deadly trap somewhere off of Hawaii.

Do you really think that FDR would consider 500,000 such American hostages to be of so little value ?

Pineapples and sugarcane ?

Who gives a crap about those ?

Hawaii was FAR more valuable than that.

Finally, the morale consequences to the American body politic would be stupendous, to put it mildly.The US voters would demand heads on platters. Could even FDR weather the resulting firestorm ? I'd think not once word got out that HE had fired Admiral Richardson for suggesting that his move of the Pacific Fleet to Oahu was NOT a good idea.

So, even if they somehow miraculously won and took Ohau they are now faced with a weakened fleet,

I'd have to think that the Japanese and American fleeets would now be much closer to parity than they had ever been before in history.

no means to regularly supply their troops there,

Like I've typed before, 1,680,000 tons of shipping could have been freed up for Operation Hawaii.

a hostile population,

Considering that 40% of Hawaii's population was of Japanese ethnicity, I think that you greatly exaggerate.

and the eventual defeat and reconquest of the island(s) taken by the US.

Granted, the USN's Atlantic Fleet WILL certainly try but I am not confident of their success without benefit of their historically secret Japanese code breaking ability. I'd predict an even fight that could go either way depending on pure luck. Certainly the winner would dominate the Pacific in the short term.

However, to that must be added the effect that a now unchecked German Navy would have on Allied efforts in the Atlantic and on the oil routes of the Caribbean.

Would the American counter-attack on Hawaii cost the UK and Russia their Lend/Lease lifelines ?

Finally, after decades of planning, a Mahanian "Decisive Battle" indeed.

In addition, the loss of not conqueroring the DEI and Malaysia will cripple their economy at home.

I see no compelling reasons that these territories would not fall as per the OTL.

This is just a major losing proposition for the Japanese.

It is true that nothing much trumps an A-bomb but then, way back in December of 1941, nobody knew that such a weapon would even work.

 

Sloniksp, you asked,

Lets imagine, that the 40-50k Japanese soldiers cramped in their vessels managed to somehow land in Hawaii undetected. Then what? Even if they had captured Honolulu what then ?

I think that I've already responded to most of your posting's items in other of my responses but here you raise an Oahu issue that I am still wrestling with.

Once Oahu was invaded and sizable Japanese forces were ashore, what combination of events, in your opinion, would cause General Short to surrender his command ?

I came up with 6 possibilities:

1.) The destruction, fall or blockade of Oahu's only three deep water ports (Pearl Harbor, Honolulu Harbor and the Port of Kaneohe) thru which American reinforcement and resupply must come ?

2,) The Japanese capture of the City of Honolulu, the home of 200,000 of Oahu's then population of 260,000 ? Or, would Short "fight to the last civlian" ? Unlikely I'd think since many living there were the military families of the USN/US Army's troops seving on Oahu.

3.) To the first use of chemiical warfare on Oahu ? Neither the Americans nor the Japanese had ever signed the 1925 Geneva restrictions on the use of chemical weapons in wartime so either could be the first user. Historically the Americans had a large stockpile of chemical weapons already stored on Oahu (at Schofield Barracks) but as of Dec.7'41 had distributed only non-functional training gasmasks to their Hawaiian Island troops. Their civilian poulations had NO masks at all and no proper training in their use even if some were somehow distributed. There were NO children's or baby sized masks available or stockpiled at all.

4.) When the last of the American warplanes/airfields were destroyed/captured thus granting the Japanese invaders unchallenged control of Hawaiian skies ?

5.) When the food/water/ammo ran out ?

6.) When the total destruction of the USN's Pacific Fleet within it's Pearl Harbor base meant that General Short could no longer carry out his primary mission orders of defending that Fleet's home base ?

Historically MacArthur left Manila as an uncontested Open City so as to minimize civilain casualties there but Manila was a Philippine city, NOT an American one.

Personally, I lean towards option #2 since the infamous Japanese Army's 6 week long "Rape of Nanking" began just four short years previous on Dec.9'37. The total deathtoll will never be accurately known but seems to hover somewhere between 100,000 and 300,000 souls.

Had the American defenders of Oahu continued to resist once Honolulu's 200,000 civilians were in IJA hands, the historical parallels would be just too horrific for General Short to ignore, IMO. Especially in light of a Nanking reminder from the IJA commander on the ground in Honolulu.

What are your thoughts on this rather disturbing surrender issue ?

 

I'll give you one thing; you are certainly well thought. The one thing you are missing is that Japan attacked Pearl Harbor to sink the Aircraft carriers. The American Carriers are key to Japan holding any real estate in the Pacific.

As soon as the Japanese even looked like they would try to occupy Hawaii, for even a short period, every US Naval resource would have been allocated to the defense of the Islands.

You propose that Japan occupies Hawaii for a short time ans uses it as a bargaining chip..........wouldn't happen.

Guam, Midway and Luzon would not wither on the vine they would be supplied through the Phillipines, Singapore and Australia. Japan could not hold Singapore without controlling the Phillipines.

 

I have been reviewing my copy of Layton's "And I Was There" and can find nothing to support your assertions. Layton says on Page 383;

"The original goal of the second phase had been the consolidation of Japan's island defense system in the Pacific for operations against the American fleet. After 'a strategic situation of long-term invincibility' had been established according to the Japanese strategic master plan, the plan's ambitious third phase called for the 'capture of Hawaii and the outlying islands, attack on the United States, Canada, Panama Canal, as well as against Central America until the United State loses it's fighting spirit and the war can be brought to a conclusion.'"

In fact, the Japanese never achieved their "Second Phase" objective of "long-term invincibility" for their defensive perimeter, and never produced any detail plans for Yamamoto, or anyone else, to attack Alaska, Hawaii, or the West Coast of the US. These were all fantasies in the minds of Japanese long range planners, as the Japanese had not the slightest capability of successfully projecting their military power to any one of these objectives. The Aleutians operation (Operation AL), according to H.P Willmott, in "The Barrier and The Javelin" was simply to block a possible advance of the US military down the Aleutian island chain with the intent of attacking the Kuriles and northern Japan. On Page 91, Willmott says;

"The immediate objective [of Operation AL] was to secure the the condition -- the neutralization of Dutch Harbor -- whereby the landing operations could be carried out. The Combined Fleet was concerned that in time the Aleutians might be developed by the Americans into a staging post for major operations. It was determined to secure what it saw as blocking positions on the line between Dutch Harbor and the Kuriles and Hokkaido."

In other words the Japanese Aleutians operation was purely defensive in nature and not some prelude to a grand offensive against the continental US.

The idea that some grandiose "Third Phase" plan of operations existed in which the Japanese would launch attacks against impossible objectives on the US West Coast, Central America, and the Panama Canal, is belied by the bitter debates, extending well into May, 1942, between the Combined Fleet, the Naval General Staff, and the Army General Staff. There was little agreement on future objectives, and literally no discussion of what, if anything, might induce the US to negotiate. There was only a sense of confused desperation and the feeling that time was rapidly running out for Japanese options.

The Midway Operation was Yamamoto's brainchild and his primary concern was clearly the destruction of the US carrier fleet. The Naval General Staff opposed the capture of Midway for several very sound military reasons, but lost the debate when Yamamoto (again) petuantly threatened to resign unless the operation was approved. The Japanese Army staff was led to believe that the ultimate objective of the Midway operation was the capture of Hawaii, and agreed to detail three Army divisions for such an objective. These three divisions may, or may not, have received orders to begin training, but by the summer of 1942, three divisions would not have been sufficient to capture Oahu, and, in any case, Japan did not possess the capability to lift or support three divisions at some 4,000 miles distance from Tokyo.

 

There are just a couple of problems with your suppositions.

First, the Japanese didn't have anywhere near a million tons of spare shipping just sitting around waiting for something to happen, regardless of your claim to the contrary. Second an invasion of the Oahu would require the support of the major part of the Japanese Navy, which also was tasked with covering the Malaya operation, the Philippines operation and various other minor points such as Guam and Wake.. Yeah, I know, you plan on ignoring the Philippines, Guam, etc. but exactly what does that buy you in terms of spare naval units?

But the major problems don't really start with logistics although that issue was patently impossible for the Japanese to overcome; the real problems are the defenses of Oahu. You've said that the only way a Japanese invasion of Hawaii can succeed is if the invasion force achieves complete tactical surprise; therein lies the insurmountable problem.

It is axiomatic in warfare that, when attacking a single objective, tactical surprise can only be achieved once.

Yet, in order to successfully invade Oahu, the Japanese had to do three things there, all of which were dependent on tactical surprise for their success and two of the three could not be done simultaneously.

1. They had to destroy completely the American naval force at Pearl Harbor and in the surrounding waters. If they weren't able to do that, any attempt at a landing is purely academic.

2. They had to destroy the American air power based on Oahu. It is a proven axiom that without air supremacy, no assault landing can prevail

3. They had to effect an assault landing against ground defenses as formidable as anywhere in the world.

The real problem is that all three of these conditions can only be brought about by the Japanese through attacks enjoying tactical surprise, but while the first two conditions might be achieved with one series of air attacks during daylight hours, as historically almost happened at Pearl Harbor, an assault landing cannot succeed at tactical surprise unless it is launched during hours of darkness. You can't have tactical surprise by both the landing forces and the carrier air forces; one or the other has to come first, which will deny the necessary condition to subsequent attacks.

In any case, assault landings rarely are able to achieve tactical surprise; a seaborne invasion force is just too difficult to conceal on approach and requires too much time to prepare the landing force once it is positioned off the target beaches. For example, The Japanese carrier force attacking Pearl Harbor remained undetected at 200 miles distance from Pearl Harbor, largely because it could run into it's launch position at 25 knots or better from over 500 miles out. An invasion convoy proceeding at a maximum of around 10 knots does not have any such luxury. In order to be able to launch it's attack it has to be within 4-5 miles of the beach and has to be there, not a few minutes before it launches the attack, but at least two to three hours beforehand. That means it has to start it's run in from under 100 miles. In an area with as much routine air and sea traffic as Pearl Harbor the odds of being spotted at that distance are overwhelming.

I can guarantee that neither the IJA, nor any other Army with any amphibious experience is going to allow their slow and vulnerable transports, packed to the gills with troops and valuable equipment, to steam within 100 miles of enemy air bases as existed on Oahu, nor for that matter an intact enemy naval base. They are going to insist that those bases be destroyed, or at least neutralized, by air or naval attack long before their precious transports come anywhere near the target. Of course, if that happens, there goes your tactical surprise.

Creating the absolute minimum conditions for a successful assault landing precludes the one other minimum condition for the success of that landing; tactical surprise.

There are other objections to the feasibility of a successful Japanese invasion of Oahu on December 7th., but I'll let you figure this one out before I dump them on you.

 

I agree with most of your statements, particularly the comment about Singapore Malaya. The Japanese were able to capture Singapore only because they had naval and air superiority. without the naval and air units that would have to be committed to the Oahu invasion, the Japanese can't take Singapore and if they can't capture Singapore, the NEI probably won't fall either. So they end up with Oahu and no oil; real smart.

I also agree that Oahu isn't going to become any bargaining chip; if the Japanese get real lucky an capture it it just makes the US public even more anxious over Japanese intentions and puts pressure on Washington NOT to negotiate. Yamamoto was extremely stupid to attack Pearl Harbor as he did, but this idea is even dumber if that is possible.