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#1 Jim Martin

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Posted 18 August 2007 - 1804 PM

I've always dismissed the idea of a Japanese invasion of Hawaii as being logistically impossible, but I've been reading "Shattered Sword: The Untold Story of the Battle of Midway", and it looks like it almost happened.

Yamamoto himself was pushing hard for an invasion of Oahu ("The Eastern Operation"):

It has commonly be supposed that any successful Japanese operation in the Central Pacific would automatically have culminated in an invasion of Hawaii. Certainly this is what Yamamoto had in mind. However, like the notion of operations in the Central Pacific itself, an invasion of Hawaii was by no means accepted within the Navy as a whole, much less by the Army. Admiral Yamamoto and his staff had been contemplating such a venture since the summer of 1941, but few others had contemplated such a notion. During the planning for the attack on Pearl Harbor, the idea had briefly been floated that a simultaneous invasion also occur against Oahu. However, such an attack was judged by Naval GHQ as being far too risky. In September 1941 the notion was dropped, though it was not forgotten by Combined Fleet. Thus, during the strategic debate that reemerged in early 1942, Yamamoto and his staff found themselves rolling not one, but two rocks uphill.

It didn't take long for both Naval GHQ and the Army to get wind of Combined Fleet's ambitions in the Central Pacific, whereupon Naval GHQ moved aggressively to put a stop to them. On 16 December, HQ sent Captain Tomioka down to Hashirajima to meet with Ugaki and discuss follow-on operations. While there, Capt. Kuroshima Kameto, Combined Fleet's "God of Operations," briefed Tomioka on operations aimed at seizing Palmyra, a tiny atoll that lay halfway between Hawaii and Samoa. Tomioka initially believed that this move was designed to help support follow-on operations into Fiji and Samoa, which was Tomioka's own favored axis of attack. Upon returning to Tokyo, Tomioka relayed the results of his meeting to both his boss, Fukudome, and to Fukudome's counterpart on the Army General Staff, Lt. Gen. Tanaka Shinichi. Tanaka saw immediately that Tomioka had been misled and that invading Palmyra was intended as a move into the Central Pacific and a stepping stone toward Hawaii, not Fiji or Samoa. He told Tomioka bluntly that the Army viewed any enlargement of the defensive perimeter as dangerous and unnecessary....


...In reaction to General Tanaka's misgivings, [Capt Tomioka] shortly had Capt Miwa Yoshitake of Combined Fleet staff come up to Tokyo to report further on Combined Fleet's plans. Miwa dutifully arrived on 27 December, 1941, and delivered a briefing on what was coming to be known within Combined Fleet as "Eastern Operation"--the invasion of Hawaii. Tomioka, alarmed, saw that he had indeed been given the wrong impression about Combined Fleet's schemes. He thereupon tasked one of his subordinates, Capt. Kami Shigenori, to prepare a logistical study of the proposed operation. Kami dutifully complied, and by 11 January Tomioka had all the ammunition he needed to shoot Combined Fleet's proposal down. While capturing Hawaii might be feasible, the logisitcal problems associated with keeping the islands' large civilian population supplied were substantial. Hawaii was not even remotely self-sufficient in basic foodstuffs. These necessities, in addition to the needs of the large garrison Japan would have to post there, would require at least sixy transport loads per month--a figure beyond Japan's meager resources. It was obvious that in the face of likely resistance from American submarines, these basic figures would need to be even further expanded.

While Kami was preparting his report, Tomioka was simultaneously working his superiors. At an Army/Navy conference in Tokyo on January 10, 1942, Admiral Nagano discussed the notion of Hawaiian operations with General Sugiyama Gen, head of the Army General Staff. Sugiyama and Nagano agreed that a direct attack on Hawaii was impossible, and that operations into the Fiji, Samoa area made better sense. General Sugiyama liked this option, because it would require less of a commitment from his branch of the service. Nagano liked it, because it was at least an indirect move against Australia.

Into this lion's den of stacked-deck politics walked Commander Sasaki Akira, a relatively junior member of Combined Fleet staff, to deliver yet another briefing to Naval GHQ on January 13th. His comrade, Miwa, not having gotten a strong negative reaction to "Eastern Operation" on his previous trip to Tokyo, Sasaki was undoubtedly expecting smooth sailing as well. Instead he was treated to Captain Kami's damning logistics study, followed by the Army's flat refusal to sanction an invasion of Hawaii, and topped off with the announcement of Nagano and Sugiyama's joint accord to proceed inot the Fiji/Samoa region instead. Sasaki thereupon retreated to Hashirajima to relay the news to Combined Fleet staff....


So...both the General Staff and Naval GHQ shut down Yamamoto's driving wish to invade Hawaii. Then, Doolittle bombed Japan:

The day after Doolittle's raid, General Tanaka privately told Captain Tomioka that he was rethinking his reservations regarding Operation MI. On the 20th (April 1942), Tanaka not only formally approved of Operation MI (the Midway operation), but also committed the Army to supplying troops for the assault. Even more intriguing, he informally asked Tomioka for more details on "Eastern Operation", which marked something of a watershed in the Army's appreciation for the scheme. The Army initially assented to Operation MI on the explicit understanding that it not be dragged into operations aimed at Hawaii. However, within a month, the Army had done an about-face on this matter, too. On 25 May, just days before the Nagumo force was slated to sail for Midway, the Army issued orders to several units to begin preparing for an amphibious attack against Hawaii. Training for the assault was to be completed by the end of September. Thus, against great odds, Yamamoto had achieved his goal--operations in the Central Pacific aimed at the destruction of the American fleet and the subsequent capture of Hawaii.


So, despite logistical limitations fully acknowledged by the Japanese, the invasion of Hawaii was a go. Obviously, the loss of their carriers at Midway forever ended this plan, but had Midway resulted in the destruction of the American carrier force with minimal losses in Japanese carriers, apparently the Army was planning to be prepared for an amphibious invasion by the end of September.

Had the Japanese not sent CarDiv 5 to Coral Sea to support the Port Moresby invasion, Shokaku and Zuikaku would have both been available to support MI, as had been planned. This would have given the Kido Butai 6 flight decks to the Americans' 3. Even after Shokaku was damaged, the authors point out that she still had enough aircraft intact and repairable that, had they been cross-decked to Zuikaku, the latter would have had a nearly-full complement of aircraft, essentially giving the Japanese 5 carrier groups with which to attack Midway. The addition of these assets may have resulted in a far different result at Midway.

Given a Japanese victory at Midway, Oahu would have been invaded in the late summer/early fall of 1942.

What happens?
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#2 KingSargent

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Posted 18 August 2007 - 1842 PM

The IJA was right. Hawaii was impossible. The defenses had been considerably beefed up since 7/12/41 and even if the Japanese had been able to get there and ashore it would have taken a long time at the end of a very long supply chain.

The whole plan is a grandiose symptom of Victory Disease. The first six months of the war had gone so astonishingly well the Japanese thought they could do anything.

And even if it succeeded and Oahu fell, it would do nothing to stop the vast American buildup that was gaining steam every day.

We did this a few years ago, and I thought that in a surprise move in the 1941 context the Japanese could have pulled it off. The IJA contribution would be Yamashita and 25th Army sent to Oahu instead of Malaya (Malaya wasn't going anywhere, the Japs could have it whenever they wanted) with Nagumo hovering off the islands providing air cover.

I still think so, except that they couldn't get there and couldn't resupply if they did.

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But supposing they manage it and the US is deprived of its forward base?

IMHO Australia would have seen an even more massive build-up than occurred. Sydney would have eclipsed Pearl Harbor as a base (it's a better harbor anyway). Emphasis would have been on retaking resources (oil) in the NEI instead of island-hopping the Central Pacific.

End result same, except the Japanese would be unable to resist committing atrocities in Hawaii, America would be REALLY pissed-off, and Japan would enter the second half of the 20th Century as a cinder.

The worst part for the US is that kids from Middle America would come home after the war speaking 'Strine. :lol: :lol:
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#3 Guest_aevans_*

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Posted 18 August 2007 - 1842 PM

If you've been reading that book, then you know that even with enough aircraft and crews to outfit a fifth carrier, Japanese doctrine, as it stood in 1942, would have prevented them -- indeed did prevent them -- from putting that carrier to sea, because their strike pakaging relied on two carrier divisions, not individual ship a/c complements.
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#4 Jim Martin

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Posted 18 August 2007 - 1848 PM

If you've been reading that book, then you know that even with enough aircraft and crews to outfit a fifth carrier, Japanese doctrine, as it stood in 1942, would have prevented them -- indeed did prevent them -- from putting that carrier to sea, because their strike pakaging relied on two carrier divisions, not individual ship a/c complements.



I haven't finished it yet, Tony. :P But the point remains that if the IJN had withheld CarDiv 5 from the Moresby op as they'd initially tried to do, all 6 carriers would have gone to Midway.
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#5 Guest_aevans_*

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Posted 18 August 2007 - 1924 PM

I haven't finished it yet, Tony. :P But the point remains that if the IJN had withheld CarDiv 5 from the Moresby op as they'd initially tried to do, all 6 carriers would have gone to Midway.


But why would they do that? The Port Moresby invasion fleet needed air cover, and Japanese ashore air bases weren't very well developed in the area, at that time.
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#6 KingSargent

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Posted 18 August 2007 - 1937 PM

But why would they do that? The Port Moresby invasion fleet needed air cover, and Japanese ashore air bases weren't very well developed in the area, at that time.

They could have not gone after Port Moresby at all.

It really amuses me that everybody at staff level on both sides acted like Moresby was a harbor equivalent to San Francisco. In 1942 it was "two tin sheds and a rickety pier."
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#7 Jim Martin

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Posted 18 August 2007 - 1941 PM

But why would they do that? The Port Moresby invasion fleet needed air cover, and Japanese ashore air bases weren't very well developed in the area, at that time.


pp. 57-58:

At first, Combined Fleet was of a mind to send just Kaga southward. Having missed the Indian Ocean operation because of the need to repair hull damage suffered in a mooring incident in Palau, she was already in home waters and had just been refitted. This would give Inoue a total of about one and a half carriers, since he already had the brand-new light carrier Shoho under his command. Inoue, however, raised strenuous objections to this.....as a result, Combined Fleet relented and on 12 April issued orders telling CarDiv 5 to proceed via Mako to Truk at the termination of their Indian Ocean sortie. They would be ready to participate in Operation MO thereafter. Yamamoto reasoned that Shokaku and Zuikaku probably couldn't get themselves into to much trouble by participating in Inoue's sideshow and might even garner some additional training in the process...."



As seen in this passage, Combined Fleet was more than willing to send a single carrier to partner with Shoho. Per Yamamoto's own perception, Moresby was a "sideshow" compared to the vital task of knocking out the American carriers, and then taking Hawaii. As Parshall and Tully point out, any target that the IJN took on was worth either committing all 6 carriers to attacking, or NONE of their carriers.
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#8 Guest_aevans_*

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Posted 18 August 2007 - 1943 PM

They could have not gone after Port Moresby at all.

It really amuses me that everybody at staff level on both sides acted like Moresby was a harbor equivalent to San Francisco. In 1942 it was "two tin sheds and a rickety pier."


Aside from being the Allies' main logistics node (and last significant outpost) on New Guinea, you mean?
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#9 KingSargent

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Posted 18 August 2007 - 2025 PM

Aside from being the Allies' main logistics node (and last significant outpost) on New Guinea, you mean?

True, but the idea that the Japanese could have built it into a base to threaten OZ is laughable. The only way they could get engineers and engineering supplies to Moresby was to sail them around New Guinea and past Northern OZ, which was beginning to bristle with air bases. And they are going to get gasoline there by carrying it in cans over the Owen Stanleys?

WE could turn Moresby into a base (never a real big one) because it was a short run from OZ and the Japanese fields on New Guinea's northern coast (and the IJN) could not interfere. But WE could have interfered mightily with the Japanese.
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#10 Tiornu

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Posted 18 August 2007 - 2042 PM

What happens?

A victory in the naval Battle of Midway does not necessarily imply a successful invasion of Midway. And the conquest of Midway does not imply that the Japanese would be able to hold it for any length of time. I'll try to come up with an analogy. Let's say that the Americans decide not to invade Guadalcanal but Guam instead. Even if the suceed in taking the island, that does not mean they can support the island or maintain sea control there. The Japanese have major bases nearby.
I am skeptical of any hypothetical Japanese invasion of a Hawaiian island.
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#11 Wobbly Head

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Posted 18 August 2007 - 2115 PM

Looking at the land controled by Japan at the end of 1941 it looks like Japan is seriously overstreached holding onto land takes manpower and they had a lot off land too hold. How many spare troops did they have for an invasion and if they did where would they get them?

The what if question about Pearl harbour I would like to know is if Hitler was struck by a sudden burst of comman sence and does not declare war and diplomaticaly distances himself from Japan? That would cause some real problems for the European theartre of war and some serious preasure on the land lease, no US bombing of Germany etc why send military aid overseas when theres a war on with Japan but none with Germany?
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#12 Jim Martin

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Posted 18 August 2007 - 2117 PM

A victory in the naval Battle of Midway does not necessarily imply a successful invasion of Midway. And the conquest of Midway does not imply that the Japanese would be able to hold it for any length of time. I'll try to come up with an analogy. Let's say that the Americans decide not to invade Guadalcanal but Guam instead. Even if the suceed in taking the island, that does not mean they can support the island or maintain sea control there. The Japanese have major bases nearby.
I am skeptical of any hypothetical Japanese invasion of a Hawaiian island.



While I agree that an invasion of Hawaii would have been a mistake, and the IJA and NGHQ were correct in their logistical assessments, Yamamoto was certainly hell-bent on taking Hawaii, and a few days prior to Midway, he finally had the buy-in of NGHQ and the Army as well. It would appear that the invasion would go forward. In which case, the question is, do they take the island? Do the waters around Oahu become the graveyard of Kido Butai? Are the assault troops massacred in the surf? I'm assuming a Japanese victory at Midway means the loss of all three American carriers. What can the Americans muster to defend Hawaiian waters after a loss at Midway?
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#13 Jim Martin

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Posted 18 August 2007 - 2125 PM

Looking at the land controled by Japan at the end of 1941 it looks like Japan is seriously overstreached holding onto land takes manpower and they had a lot off land too hold. How many spare troops did they have for an invasion and if they did where would they get them?


Unfortunately, that's beyond the scope of this book, anyway. I'd suspect you'd have to go back to original sources to determine what their tentative OOB was for the invasion of Oahu, unless someone knows of a book regarding the planned invasion?
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#14 KingSargent

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Posted 18 August 2007 - 2157 PM

Looking at the land controled by Japan at the end of 1941 it looks like Japan is seriously overstreached holding onto land takes manpower and they had a lot off land too hold. How many spare troops did they have for an invasion and if they did where would they get them?

They didn't have any spare troops. The IJA wouldn't pull them out of China. The Pacific War was on a starvation budget. After Singapore fell, Yamashita's troops went to conquer the NEI and Burma. At one point (1943 IIRC) the IJA had one REGIMENT occupying and defending the whole NEI.
Had the IJA sanctioned the use of troops from China, there still would have been the problem of transports and fuel to get a large force to Oahu.

The what if question about Pearl harbour I would like to know is if Hitler was struck by a sudden burst of comman sence and does not declare war and diplomaticaly distances himself from Japan? That would cause some real problems for the European theartre of war and some serious preasure on the land lease, no US bombing of Germany etc why send military aid overseas when theres a war on with Japan but none with Germany?


Trust me, the EEVUL PLOTTER FDR™ would have found a way. He had the USN actively at war with Germany for months before 7/12/41*.

If nothing else, he would have argued "The Commonwealth and the Dutch are our Allies against Japan, we should help them against Germany since they are helping us in the Pacific."
In really dire straits (like Congress having the balls to impeach his ass for making war without permission) he could have said "Hey, I'm giving them all this stuff so they can fight Japan! Is it MY fault they are using it against Germany?"

* Among other things, on 7/12/41 Yorktown and what became TF17 was escorting a large British troop convoy headed for the ME. IIRC, this was the 18th Division which was diverted to Singapore just in time to go into Yamashita's game bag. Yorkie & Co. were diverted to the Pacific via the Panama Canal.
But what if they had kept going through the IO? They would have been in the IO and/or Western Pacific by February '42. If they didn't accomplish anything in the IO, they could at least have been in the Coral Sea long before May.
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#15 Jim Martin

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Posted 18 August 2007 - 2209 PM

They didn't have any spare troops. The IJA wouldn't pull them out of China.


Except that after the Doolittle Raid, they did in fact designate troops for a Hawaii operation, to the extent of pulling them from active operations to begin amphibious assault training.
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#16 KingSargent

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Posted 18 August 2007 - 2210 PM

While I agree that an invasion of Hawaii would have been a mistake, and the IJA and NGHQ were correct in their logistical assessments, Yamamoto was certainly hell-bent on taking Hawaii, and a few days prior to Midway, he finally had the buy-in of NGHQ and the Army as well. It would appear that the invasion would go forward. In which case, the question is, do they take the island? Do the waters around Oahu become the graveyard of Kido Butai? Are the assault troops massacred in the surf? I'm assuming a Japanese victory at Midway means the loss of all three American carriers. What can the Americans muster to defend Hawaiian waters after a loss at Midway?

Midway was a miracle. If it had gone the way all the other 1942 battles did, each side would have lost a CV. Tiornu is right, the Japanese Midway Invasion force wasn't any stronger than the one sent to Wake in '41, but Midway was much more heavily defended than Wake had been.

In any case, if the IJN:USN loss ratio had been even at Midway, the USN had Saratoga in the Pacific (she barely missed Midway) and Wasp was coming over from the Atlantic (she was at Guadalcanal in August, recall).

The time it took between Midway and the hypothetical Hawaiian invasion would have given the US time to build up air power in Hawaii. Oahu wouldn't be the only airbases, either. Not to mention a few skillion USN subs between the Mandates and Hawaii.
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#17 KingSargent

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Posted 18 August 2007 - 2211 PM

Except that after the Doolittle Raid, they did in fact designate troops for a Hawaii operation, to the extent of pulling them from active operations to begin amphibious assault training.

I'll take your word for it
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#18 Jim Martin

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Posted 18 August 2007 - 2222 PM

I'll take your word for it



I just checked the endnotes for that statement by Parshall and Tully:

Stephan, John. Hawaii Under the Rising Sun Honolulu: University of Hawaii Press, 1984

p.117: The original operational order (Dairikushi no.1159) gave notification to Seventh and Second Divisions to prepare for an invasion. These two divisions were soon augmented with the Fifty-Third Division, an independent engineer regiment, and a tank regiment.


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#19 Garth

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Posted 18 August 2007 - 2242 PM

What can the Americans muster to defend Hawaiian waters after a loss at Midway?


Given a projected invasion date of September, allowing ~3 months to concentrate forces and assuming Torch gets put on hold? The three remaining fleet carriers for starters - Saratoga (which just missed Midway), Wasp and Ranger (speculation that the USN would HAVE to accept sending her with her limitations into the Pacific) - plus the one CVE, Block Island. 10 or 11 BBs ... two or three fast BBs (North Carolina, Washington, and probably South Dakota and Indiana), three of the "Big Five" BBs (Tennessee, Colorado and Maryland), the three Mississippis and Pennsylvania.

Possible wildcards (depending on the extent to which the USN would want to gut the Atlantic theatre to save Hawaii and how fast these ships could get there) would be the four CVEs that went with Ranger for Torch, the Nevada (entered her rebuild in June after providing firesupport at Attu) and Massachussetts, Arkansas, New York and Texas.

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#20 KingSargent

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Posted 18 August 2007 - 2254 PM

Given a projected invasion date of September, allowing ~3 months to concentrate forces and assuming Torch gets put on hold? The three remaining fleet carriers for starters - Saratoga (which just missed Midway), Wasp and Ranger (speculation that the USN would HAVE to accept sending her with her limitations into the Pacific) - plus the one CVE, Block Island. 10 or 11 BBs ... two or three fast BBs (North Carolina, Washington, and probably South Dakota and Indiana), three of the "Big Five" BBs (Tennessee, Colorado and Maryland), the three Mississippis and Pennsylvania.

Possible wildcards (depending on the extent to which the USN would want to gut the Atlantic theatre to save Hawaii and how fast these ships could get there) would be the four CVEs that went with Ranger for Torch, the Nevada (entered her rebuild in June after providing firesupport at Attu) and Massachussetts, Arkansas, New York and Texas.

--Garth

That was June 1943 that Nevada was at Attu. I doubt that Ranger would be sent, she was operating with the British Home Fleet while the available Brit CVs went to the IO.
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