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Should The Japanese Have Followed The Pearl Harbor Attack With A Land Assault?


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#181 Rich

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Posted 16 April 2020 - 1727 PM

Assume the Southern Drive is largely (but not quite entirely) off.  The raw numbers are pretty straightforward.   Something about 325 Diahatsu and 185 Shohatsu  available could carry a single-wave assault force of 33,000 troops, plus some dozens of the bigger landing craft.   Over one million tons of shipping, allowing both a 70,000 man assault force with armor against Oahu in addition to 4 Midway- sized air base units and garrisons set up on the outlying islands.   The divisions these could draw from would be 16th, 48th, 4th, 2nd, 7th, 53rd and 54th.  The fleet – including the battleships and many cruisers and destroyers – would require about 350,000-400,000 tons of tanker/oiler supply (out of 645,000 tons available in total) to stay 6 weeks at sea.   Nagumo would gets 9 carriers,  (Hosho, Zuiho, Ryujo added to the original 6 KB) for a total of about 470 combat aircraft including 180 Zeros, (these would not be on Formosa because Luzon is being delayed).   Also, the escort carrier Taiyo with another 20 Zeroes.  Add to that 100 seaplanes and a hundred or more twin engine bombers ready to stage forward to captured fields from the Marshalls.

 

Um, no, there were 312, Daihatsu (14-meter type), 315 Shohatsu (10-meter type), and 60 Toku-Daihatsu (18 meter type) as of December 1941. Aira Takizawa told you that twelve years ago.

 

312 X 70 = 21,840

315 X 30 = 9,450

60 X 120 = 7,200

 

So all your problems are solved man! 38,490 Sekret Ninja SLNF...and some army dudes! You can conquer the world!

 

Oh, wait...

 

Hosho? 1st Fleet air cover? 25 knots? She can't even keep up with Kaga. 11 A5M4 and 8 B4Y1 aboard?

Rjujo? 29 knots at least, but 12 A5M4 and 14 B4Y1 aboard?

Zuiho? 1st Fleet Air cover? 28 knots at least, but 12 A5M4? At least she had 12 B5N.

 

Taiyo? 21 knots? She was completed 2 September, worked up through October and started loading aircraft to ferry to 11th Air Fleet on 10 November at Sasebo. A5M4 again, no Zeroes.

 

Zeros? From Formosa? You mean the Tainan Naval Air Group and 3d Naval Air Group of 21st Naval Air Flotilla? They have 107 A6M2/21.

 

Kido Butai had 126 A6M aboard. 11th Air Fleet had 132 (25 were in Indochina).

 

Only 469 A6M1, A6M2-11, and A6M2-21, A6M3-32, including sub-types, were completed by the end of October 1941, probably the latest production that might get in service...and that's probably being generous. That is also including 113 of the A6M3-32, whose short range was unsuitable for carrier operations. So there were 356 carrier-suitable aircraft...and the Kido Butai and 11th Air Fleet between them had 258 of those.

 

BTW, the IJN had 24 AO and 2 AOG in commission on 7 December 1941. Seven of them - not quite one-third - were required to support Kido Butai. Four others were with the Southern Force's Distant Cover Unit. One (teeny little 380 GRT Moji Maru) was with the South Seas Force. The AO had a combined displacement of 233,657 GRT.

 

 

 

Would it work?  Not necessarily, but the basic numbers are there.  It would probably all come down to whether Nagumo got surprise in the first attack or not.  In the meantime the southern drive could have still cobbled together the occupation of Borneo, Mindanao and maybe even the Celebes in the meantime.

 

The "basic numbers" aren't there.

 

Except the Japanese assumed the conquest of the Dutch East Indies required Malaya and the Philippines as prerequisites.


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#182 glenn239

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Posted 18 April 2020 - 1001 AM

Rich The "basic numbers" aren't there.

 

 

 

 

Nagumo Force – 120 VF, 135 VB, 144 VT = 399 aircraft.

CVL’s – 80 VF, 18 VT = 98 aircraft

CVS and CS = 90 seaplanes

Land Based (Marshalls, etc) - about 200.

 

Total of 587 combat aircraft aboard ships, (not including seaplanes carried by battleships and cruisers) plus maybe 200 waiting to stage forward at Marshalls and elsewhere, for a total of about 790 aircraft, not including seaplanes aboard cruisers and battleships.   Nagumo is there to flatten the airfields with 120 Zeroes and 135 Vals in two waves and Short’s air forces are effectively wiped out. (the CVL's with 80 Zeroes cover the carriers and their 18 VT do the scouting).   Lexington and Enterprise then exchange themselves for 2 IJN fleet carriers knocked out, and the US has about 0 aircraft in the Hawaii theatre versus 600 Japanese of which about 350 are carrier based on the 8 flat tops operational and the remaining 250 are seaplanes or land based.   Kimmel has Saratoga in California with 80. 


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#183 glenn239

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Posted 18 April 2020 - 1008 AM

Rich Um, no, there were 312, Daihatsu (14-meter type), 315 Shohatsu (10-meter type), and 60 Toku-Daihatsu (18 meter type) as of December 1941. Aira Takizawa told you that twelve years ago.

 

 

I’d pulled the numbers for the two types from the intial invasion ops here,

 

http://niehorster.or...japan/_ops.html

 

So all your problems are solved man! 38,490 Sekret Ninja SLNF...and some army dudes! You can conquer the world.

 

 

Your numbers are broadly the same scale of capacity as what I just posted.  And that’s a total TO&E lift capacity of 38,000 super duper secret ninjas per wave, not 38,000 in total.  This is the no pissing around scenario, right?  The US defenses of 2 divisions were split between north and south coasts, so that’s a 3:1 advantage in divisions for the attacker in the first wave, rising to 6:1 for the second.   The south coast is also about a 20 mile front spanning from Barber’s point in the west to Wiamanalo Beach in the east.    Coastal artillery was heavy, but one division for a front that size was too thin.  

 

Zeros? From Formosa? You mean the Tainan Naval Air Group and 3d Naval Air Group of 21st Naval Air Flotilla? They have 107 A6M2/21.

 

 

Correct.  If the Southern Drive is off and it’s all east, then the Zeros based on Formosa would be going east, not south.  You are interested in logistics.  Tell me your opinion on how long MacArthur’s air forces could conduct offensive operations at a range of 500-600 miles against shipping hugging the Chinese coast before MacArthur runs out of supplies?   And, after running out of supplies, if Davao has fallen and the nearest operational USN base is in California, how does Short get him more supplies?

 

Hosho? 1st Fleet air cover? 25 knots? She can't even keep up with Kaga. 11 A5M4 and 8 B4Y1 aboard?

 

 

I credited Hosho with being able to accommodate 18 x Tainan Zeroes.   In terms of Hosho’s lower speed relative to Nagumo, the Tainan crews were training to provide air cover to bombers at a range of 500 miles from Formosa.  Why would Hosho being, say, 40 miles north of Nagumo after the dash to the south cause difficulties for those same pilots providing CAP cover for Kido Butai?   Hosho would be constantly falling behind, but never too far behind that she could not perform a CAP function.

 

Rjujo? 29 knots at least, but 12 A5M4 and 14 B4Y1 aboard?   Zuiho? 1st Fleet Air cover? 28 knots at least, but 12 A5M4? At least she had 12 B5N

 

 

Ryujo is credited with 21 x A6M2 and 9 x B5N1, as per Eastern Solomons.  Ditto Zuiho.  Ryujo’s air group is listed here,

 

http://niehorster.or...-air-fleet.html

 

A5M’s and B5N1’s, not B4Y1’s.  The B5N1’s had been superseded in service on the fleet carriers by the B5N2’s, freeing up over a hundred B5N1’s for other duties such as filling Ryujo’s compliment.  AFAIK, there was no need for Ryujo to carry the B4Y.

 

Taiyo? 21 knots? She was completed 2 September, worked up through October and started loading aircraft to ferry to 11th Air Fleet on 10 November at Sasebo. A5M4 again, no Zeroes.

 

 

Until Tainan Zeros proved they could hit Clark from Formosa, Taiyo was earmarked to carry fighters to attack Luzon.  Why would Taiyo not be able to do what Taiyo was actually scheduled to do?

 

Tainan had 107 Zeros.   18+21+21+20  = 60 to cover Nagumo’s carriers, plus 20 more arriving on the slower Taiyo, allowing him to allocate all 120 Zeroes, (not 81) against Pearl Harbor. 

 

Kido Butai had 126 A6M aboard. 11th Air Fleet had 132 (25 were in Indochina).

 

 

KB had 120 Zeroes aboard – 21+21+21+21+18+18 = 120

 

BTW, the IJN had 24 AO and 2 AOG in commission on 7 December 1941. Seven of them - not quite one-third - were required to support Kido Butai. Four others were with the Southern Force's Distant Cover Unit. One (teeny little 380 GRT Moji Maru) was with the South Seas Force. The AO had a combined displacement of 233,657 GRT.

 

 

I said oilers and tankers, not just oilers.  Total number of both types combined translated to about 650,000 tons capacity.  An invasion fleet might have 160,000 tons of fuel capacity aboard for a cruise radius of about 7,000nm.  Plus, about a 10% overload of 16,000 tons.  It might take a radius of 21,000nm to achieve the mission, meaning something about 16 oilers with roughly 160,000 tons plus another 200,000 tons available on tankers to replenish the oilers without these having to sail all the way back to Japan.  It’s doable only if the Southern Drive is seriously curtailed.   The number of oilers I track at 27 for 275,000 tons capacity and the number of tankers at 39 at 372,000 tons capacity.


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#184 Rich

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Posted 18 April 2020 - 1446 PM

412 B5N2 were completed through August 1941 and end of initial production. Production did not begin again until April 1942, with another 200 built. There were 144 with the Kido Butai. I wonder where the other 268 went?

365 B5N1 were completed through 1 January 1940. The lack of success of the B5N1 was what led to the B5N2 for frontline service...and the remaining B5N1 were converted to B5N1-K trainers, 48 at the 1st Naval District, and 12 at the 2d Naval District. The 12 on Zuiho were the only one's truly "operational". I wonder where the other 193 went?

Zeroes? Okay, sure, Kido Butai had 120 aboard, whatever you like to ignore, all /21 types. 11th Air Fleet had 132. Out of 290 completed /21 through October. I wonder where the other 38 went?

 

Okay, so all operational carrier assets trundle off to assault Hawaii. Check.

 

Good to see your consistency...all vessels that can carry oil are fleet oilers. Check.

 

"Seriously curtailed"? In your scenario, there cannot be any invasions in Malaya or the Philippines, so no Second and Third Phase operations against the Dutch. It just requires the Japanese to not be Japanese and ignore their strategic objectives as they saw them. Check.

 

Have fun storming the castle! :D


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#185 glenn239

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Posted 21 April 2020 - 1338 PM

Correction on Hosho - in checking, her elevators were too small for the A6M2 Zero.


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#186 glenn239

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Posted 21 April 2020 - 1501 PM

Rich "Seriously curtailed"? In your scenario, there cannot be any invasions in Malaya or the Philippines, so no Second and Third Phase operations against the Dutch.

 

 

Luzon and Malaya could not happen in December 1941.  Thailand, Borneo and Mindanao could using second line IJA and IJN air forces for cover.   Any second phase after Hawaii would be an advance northwards from Mindanao against Luzon, and an invasion of Java from Indochina using airpower based at Borneo and 1st Air Fleet in support.  This, of course, requires that Kido Butai survives a Hawaiian adventure sufficiently intact to undertake a subsequent operation.  

.

It just requires the Japanese to not be Japanese and ignore their strategic objectives as they saw them. Check.

 

 

Yes, it’s totally at odds with historical Japanese outlook and intentions and a completely theoretical exercise.  But the raw capabilities were there had the intentions been different.

 

412 B5N2 were completed through August 1941 and end of initial production. Production did not begin again until April 1942, with another 200 built. There were 144 with the Kido Butai. I wonder where the other 268 went?

 

 

Some will have been lost in China or in accidents.  I don’t think the IJN had too many in reserve when the war started.   After Pearl Harbor the establishment on the carriers dwindled, as if the number of B5N2’s actually in reserves was quite small.  I seem to recall a number of land based units being equipped with B5N2’s in the early 1942 timeframe, to the tune of perhaps about 60. 

 

365 B5N1 were completed through 1 January 1940. The lack of success of the B5N1 was what led to the B5N2 for frontline service...and the remaining B5N1 were converted to B5N1-K trainers, 48 at the 1st Naval District, and 12 at the 2d Naval District. The 12 on Zuiho were the only one's truly "operational". I wonder where the other 193 went?

 

 

Once withdrawn from frontline service, these were available for various training and or land based or second line combat units.  If committed at Hawaii, the B5N1 was not suitable for anti-ship combat from CVL's.  The torpedo attack capacity of the lighter carriers was minimal.   The primary advantage of the lighter carriers at Hawaii were the additional Zeros and scouting capacity, and that they could transfer their aircraft to outlying bases as they withdrew.

 

Okay, so all operational carrier assets trundle off to assault Hawaii. Check.

 

â

Check for the most modern types, A6M2, D3A1, B5N2.  Pretty much Operation Kitchen Sink.  But, the recently replaced older types (A5M4, B5N1, D1A1) did form a reserve pool of several hundred planes that could have been tapped for frontline carriers in a pinch.   For example, if B5N2 numbers had run short they could have supplemented with B5N1's.  

 

 Good to see your consistency...all vessels that can carry oil are fleet oilers. Check.

 

 

Fleet oilers could refuel ships at sea.  Tankers could not.   I do not know if oilers could refuel from tankers at sea or not.  Carrier logistics also would have been tight.


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#187 Rich

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Posted 21 April 2020 - 1530 PM

 

Rich "Seriously curtailed"? In your scenario, there cannot be any invasions in Malaya or the Philippines, so no Second and Third Phase operations against the Dutch.

 

 

Luzon and Malaya could not happen in December 1941.  Thailand, Borneo and Mindanao could using second line IJA and IJN air forces for cover.   Any second phase after Hawaii would be an advance northwards from Mindanao against Luzon, and an invasion of Java from Indochina using airpower based at Borneo and 1st Air Fleet in support.  This, of course, requires that Kido Butai survives a Hawaiian adventure sufficiently intact to undertake a subsequent operation.  

.

It just requires the Japanese to not be Japanese and ignore their strategic objectives as they saw them. Check.

 

 

Yes, it’s totally at odds with historical Japanese outlook and intentions and a completely theoretical exercise.  But the raw capabilities were there had the intentions been different.

 

412 B5N2 were completed through August 1941 and end of initial production. Production did not begin again until April 1942, with another 200 built. There were 144 with the Kido Butai. I wonder where the other 268 went?

 

 

Some will have been lost in China or in accidents.  I don’t think the IJN had too many in reserve when the war started.   After Pearl Harbor the establishment on the carriers dwindled, as if the number of B5N2’s actually in reserves was quite small.  I seem to recall a number of land based units being equipped with B5N2’s in the early 1942 timeframe, to the tune of perhaps about 60. 

 

365 B5N1 were completed through 1 January 1940. The lack of success of the B5N1 was what led to the B5N2 for frontline service...and the remaining B5N1 were converted to B5N1-K trainers, 48 at the 1st Naval District, and 12 at the 2d Naval District. The 12 on Zuiho were the only one's truly "operational". I wonder where the other 193 went?

 

 

Once withdrawn from frontline service, these were available for various training and or land based or second line combat units.  If committed at Hawaii, the B5N1 was not suitable for anti-ship combat from CVL's.  The torpedo attack capacity of the lighter carriers was minimal.   The primary advantage of the lighter carriers at Hawaii were the additional Zeros and scouting capacity, and that they could transfer their aircraft to outlying bases as they withdrew.

 

Okay, so all operational carrier assets trundle off to assault Hawaii. Check.

 

â

Check for the most modern types, A6M2, D3A1, B5N2.  Pretty much Operation Kitchen Sink.  But, the recently replaced older types (A5M4, B5N1, D1A1) did form a reserve pool of several hundred planes that could have been tapped for frontline carriers in a pinch.   For example, if B5N2 numbers had run short they could have supplemented with B5N1's.  

 

 Good to see your consistency...all vessels that can carry oil are fleet oilers. Check.

 

 

Fleet oilers could refuel ships at sea.  Tankers could not.   I do not know if oilers could refuel from tankers at sea or not.  Carrier logistics also would have been tight.

 

WelltodoReadyIbex-size_restricted.gif


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#188 Ken Estes

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Posted 29 April 2020 - 2143 PM

Of interest, and new:

 


Advantage Japan: The Imperial Japanese Navy's Superior High Seas Refueling Capability. Authors: Fuquea, David C.1 Source: Journal of Military History. Jan2020, Vol. 84 Issue 1, p213-235. 23p.   The arrival of Japanese bombers and torpedo planes over Pearl Harbor on the morning of 7 December 1941 was a complete shock to Americans. This was not only because the two nations were at peace, but also because the Japanese naval striking force seemed to have possessed a near miraculous ability to support and supply its carriers on the long journey to and from the Japanese home islands into the heart of America's Pacific defenses. It was Japanese mastery of the logistical challenges as much as their audacity that produced the strategic surprise. The ability to keep task forces at sea refueled, regardless of weather, was a capability of which the United States Navy could only dream as the war in the Pacific began. In reality, the Imperial Japanese Navy (IJN), in the war's early years, maintained a near monopoly on large-scale, underway refueling, contributing to its "heady" early success over its American and British naval opponents. [ABSTRACT FROM AUTHOR]      
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#189 Nobu

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Posted 29 April 2020 - 2259 PM

Of great interest!


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#190 glenn239

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Posted 30 April 2020 - 0834 AM

The TROM of one of the oilers assigned to Nagumo's TF here,

 

http://www.combinedf...m/Kyokuto_t.htm

 

13-14 November 1941:
Oilers KYOKUTO, KENYO, SHINKOKU and KOKUYO MARUs conduct fueling at sea exercises with CarDiv 1's AKAGI, DesRon 1, CruDiv 8, CarDiv 2's SORYU and HIRYU and CarDiv 5's SHOKAKU and ZUIKAKU.

 

18 November 1941: The Hawaii Operation:
Departs Saiki. Seven oilers are assigned to the Hawaii Operation, but the IJN’s practical experience in refueling at sea is almost nil. Earlier in the month, three refueling exercises were held in Sukumo Bay and the Ariake Sea. Now, while enroute to the Kuriles, all units in the carrier formation are refueled ten times.

 

There was no need to refuel the carriers ten times on the way to the Kuriles from Saiki Bay except for training.  The TROMs suggest that the oilers in question were prepared to an extent ahead of time, but also, that the crews had basically zero hands-on experience with at sea refuelling only weeks before the mission was scheduled. 


Edited by glenn239, 30 April 2020 - 0835 AM.

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#191 Rich

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Posted 30 April 2020 - 1143 AM

How is that "new"? The Japanese had 24 AO and 2 AOG in commission and trained for underway replenishment on 8 December 1941...although not all would qualify as a "fast" tanker or "large".

 

The US "only" had 14 of the purpose-designed Cimmaron and Kennebec-class large, fast tankers completed by the same date and only around a dozen were already in commission as of 7 December 1941, plus the 17 older, mostly slower, and not so large tankers acquired prior to 1922. So given the relative size of the fleets, indeed the Japanese were relatively more "capable".

 

Did you think the contrary was ever being argued?


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#192 Ken Estes

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Posted 01 May 2020 - 1904 PM

It is of interest and new when I read that the IJN had over 60 tankers supporting the fleet in Dec41 of which some 30 were capable fast oilers. He also eschews notions that the IJN had to do astern refueling perforce. The IJN also had fitted their CV and BB class ships to refuel smaller ships at sea. [ETA] He also finds the Cimarron's were finished in 1940 without underway refueling gear, and that their design was based upon the IJN "Japanese Flyer" fast oilers that BuCon & Arch had studied for years.

 

Maybe I need to get out more?


Edited by Ken Estes, 01 May 2020 - 1914 PM.

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#193 Rich

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Posted 01 May 2020 - 1959 PM

It is of interest and new when I read that the IJN had over 60 tankers supporting the fleet in Dec41 of which some 30 were capable fast oilers. He also eschews notions that the IJN had to do astern refueling perforce. The IJN also had fitted their CV and BB class ships to refuel smaller ships at sea. [ETA] He also finds the Cimarron's were finished in 1940 without underway refueling gear, and that their design was based upon the IJN "Japanese Flyer" fast oilers that BuCon & Arch had studied for years.

 

Maybe I need to get out more?

Except they didn't. They had 26 oilers, not 30, and they were not all large fast fleet oilers. Yes, there were more tankers "supporting the fleet", because practically every Japanese tanker was technically IJN reserve. However, most of them were empty swinging at anchor, because of the lack of oil. This is nothing new, but it is exaggerated. The Japanese had refitted their "CV and BB class ships to refuel smaller ships"? So what? So did the USN.  They did both astern and abeam refueling...so did the USN.

 

Yes, the Cimmarons were built as emergency defense tankers...the UNREP gear was added later as needed. More were built, more were fitted. The Japanese? Not so many.

 

Yeah, get out more...hopefully to one of our parties in the near future! :D Stay safe Ken!


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#194 RETAC21

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Posted Today, 12:25 PM

Completely unrelated to the topic, but interesting:

http://www.navweaps....ck_Analysis.pdf


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#195 Nobu

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Posted 11 minutes ago

That clips held battleship turrets in was informative. Impressive underwater photography, including what appears to be a giant crab on one of Kirishima's propellers.


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