Japanese figure out their goose is cooked before Midway

[Saphroneth]

Whoops. Skipped over the oversized divisions and battalions bit. I am guessing around 90,000 men.

Minimum of 90,000, I think.
Oahu's a bugger - it's just the right size. Small enough to not permit outflanking, large enough to defend in depth.

 

[CalBear]

What was the American garrison on Oahu in the summer of 1942?

Army ground component was 74K+. AAF was 16K+. Two+ Marine Defense Battalions (~2,500 personnel from the 1st, 3rd & 4th, with other elements on the "outer islands") were also in place. There was also somewhere north of 10,000 USN shore personnel (service troops, mechanics, ship-fitters, etc.) plus crews from the ships in port being repaired/refit, this number varied on an almost daily basis.

There were roughly 15,000 troops on other islands, mainly on Hawaii (aka the Big Island).

Combat aircraft were considerably in excess of 300, the majority being AAF fighters. Had Midway gone badly for the U.S. there were already plans in hand to expand the air component to 350+ fighter and two Heavy Bombardment Groups (these additional resources were distributed elsewhere, both to Australia and the ETO once the strategic picture in the Pacific changed).

It is also not unreasonable to assume that the U.S. would have altered deployment of both the 1st & 2nd Marine divisions if Hawaii was seen to be at grave threat. These were the units sent to the SW Pacific IOTL, it would seem likely that at least elements of one division would be allocated to Hawaii. The pre-Midway plan for the Oahu Army garrison called for an additional full division plus fillers to round out TOE of units in place. This would have brought the Oahu Amy Garrison to over 107,000 combat troops.

 

[deathscompanion1]

How many troops could the Japanese shift thousands of miles in one go?

Torch was done from North America but that was against far weaker opposition 200,000 odd troops seems logistically impossible to shift soon enough to do more than pile up more bodies on the beaches.

 

[MattII]

Torch was also well planned (including having broken enemy codes), had some 'local' (it's less than 2000 km from Britain to Gibratar, at least at minimum distance, Plus, well Gibraltar), and the backing of two major industrial nations.

 

[deathscompanion1]

Torch was also well planned (including having broken enemy codes), had some 'local' (it's less than 2000 km from Britain to Gibratar, at least at minimum distance, Plus, well Gibraltar), and the backing of two major industrial nations.

Well yes but the Japanese just did things. I think it would fail disastrously but I'm asking whether they would think it had a hope in hell of succeeding if they make a hopelessly overcomplicated plan and throw loads of men and ships into the meat grinder as they usually did.

 

[Carl Schwamberger]

How many troops could the Japanese shift thousands of miles in one go?

Torch was done from North America but that was against far weaker opposition 200,000 odd troops seems logistically impossible to shift soon enough to do more than pile up more bodies on the beaches.

Japanese Army did a appreciation discussion of attacking the Hawaiian islands. They thought a initial assault force of 5,000 to 10,000 men possible & another 20,000 to 30,000 is sucessive lifts spread over many weeks. They told their naval counter parts they were not much interested. At the time the 'Fiji Operation' was foremost in the mind of senior Japanese leaders. They thought this would cause Australia & New Zealand to sue for peace, and that it would be easy since the Fiji, Samoan, & other islands in the region were lightly defended. They judged a advance force of 5,000 to 10,000 men should be able to accomplish much in that direction.

Had Yamamoto not presented the Midway operation, or been overruled on it, the Japanese main fleet would have been committed to supporting the Fiji operation. Thus there would have been four extra carriers and their air groups opposing the USN attack to the Solomons & Guadalcanal. Conversely the USS Yorktown would have been properly repaird/refitted by this time, the Saratoga returned from its repair/refit, & the Wasp not far behind.

 

[deathscompanion1]

Japanese Army did a appreciation discussion of attacking the Hawaiian islands. They thought a initial assault force of 5,00 to 10,000 men possible & another 20,000 to 30,000 is sucessive lifts spread over many weeks. They told their naval counter parts they were not much interested. At the time the 'Fiji Operation' was foremost in the mind of senior Japanese leaders. They thought this would cause Australia & New Zealand to sue for peace, and that it would be easy since the Fiji, Samoan, & other islands in the region were lightly defended. They judged a advance force of 5,000 to 10,000 men should be able to accomplish much in that direction.

10:1 odds...

 

[Carl Schwamberger]

10:1 odds...

Judging from the awsome superiority of the Japanese warrior & combat methods, proven in China, Malaya, Dutch East Indies, ect... the degenerate mongrel US soldiers should be not a problem. Most of that 100,000 would be non combat support units. No better than the Korean labor battalions that accompanied the Japanese army. The fall of Singapore would be a good model for a attack on Oahu

 

[deathscompanion1]

Judging from the awsome superiority of the Japanese warrior & combat methods, proven in China, Malaya, Dutch East Indies, ect... the degenerate mongrel US soldiers should be not a problem. Most of that 100,000 would be non combat support units. No better than the Korean labor battalions that accompanied the Japanese army. The fall of Singapore would be a good model for a attack on Oahu

I want so hard to ignore that this is tongue in cheek and rip it to shreds. Its so tempting.

 

[ThePest179]

Most Pacific War experts know how the US figured out Midway would be the location of the next Japanese offensive. On May 19, the Island was ordered to broadcast an uncoded message, that they
would soon be short of fresh water; Pearl Harbor then sent a reply, also uncoded, that a water barge was on its way. Allied listening stations were rewarded the same day with a Japanese message
reporting that “AF” the target of their next offensive, was running short of water. But, what if in mid-May 1942, a Japanese sailor, after transcribing the running short of fresh water message, had
turned to his superior to ask, “Why are they broadcasting this message in the clear? Don’t they care if we know that Midway is running short of water?” What if, acting on this the young communications officer had passed along his doubts? What if more experienced cryptographers and cipher specialists in Tokyo had not dismissed the idea that Imperial Japan’s codes could be broken; what if they had considered the possibility that the Americans could possibly be playing out an intelligence gambit. They might have reasoned, “If the Americans have been able to read some of our messages and are attempting to link potential objectives with cipher designations, would not this little message be an excellent way to trick us into confirming the code word for Midway? What if, with a red flag raised,
naval staff at Imperial General Headquarters Tokyo broadcast the now famous message of May 19, 1942, referring to “AF” being short of water not merely as a routine signal but as the first salvo in a Japanese intelligence offensive designed to lure the Americans to battle on terms favorable to Japan?

That entire statement was ripped right from a book called What If? Is that plagiarism?

 

[Alex1guy]

It's not just the raw tonnage lost, it's the initiative, with a total US navy wipeout at Midway, they could have taken a lot of strategic objective, maybe even Hawaii, that would have been hell to dislodge them from afterwards.

The Japanese at no stage of the war possessed the forces it needed to invade Hawaii while maintaining it's over stretched garrisons in the Pacific, Indonesia and China. The logistics of supplying such a force would be a huge stretch and force the Japanese to fight on the other side of the Pacific miles away from their supply bases against what will be a well entrenched American garrison, who will be receiving reinforcements and supply from CONUS (which is closer).

 

[Carl Schwamberger]

I want so hard to ignore that this is tongue in cheek and rip it to shreds. Its so tempting.

Yeah, would be like shooting fish in a barrel. On a serious note we do have to remember there were more than a few Japanese leaders who took a similar outlook very seriously. ie: There was Col Ichiki who took his 1100 man detachment into a frontal attack against what he was told were 5,000 US soldiers. Victory disease was a very real thing with the Japanese leaders in 1942.

 

[MattII]

Well yes but the Japanese just did things. I think it would fail disastrously but I'm asking whether they would think it had a hope in hell of succeeding if they make a hopelessly overcomplicated plan and throw loads of men and ships into the meat grinder as they usually did.

Depends how much of a battle they have with Midway proper. If it's similar to Wake, then they might decide not to bother, figuring that such a major base that much further away would be impossible to take, and even more so to keep supplied.

 

[Glenn239]

How many troops could the Japanese shift thousands of miles in one go?

Though the problem was huge, the core issue wasn't the logistics, it was airpower and the inability of the IJN to attain it. By summer 1942 Hawaii's land based airpower was beyond the IJN carrier fleet's capacity to deal with, while the outer island airfields were all adequately garrisoned meaning that in any offensive the Japanese could only count on seaplane bases to enhance their carriers.

 

[Glenn239]

Japanese Army did a appreciation discussion of attacking the Hawaiian islands. They thought a initial assault force of 5,000 to 10,000 men possible & another 20,000 to 30,000 is sucessive lifts spread over many weeks.

That's the first time I've ever seen it claimed that the 3 divisions (2nd, 7th, 52nd) earmarked in May 1942 by the IJA for the assault landing totalled only 10,000 men. I thought after reinforcement, it would have been more like 50,000 - 75,000 men.

What's your source?

 

[usertron2020]

It's just that since Midway was the target of their next offensive this one might stand out. Was taking some initiative really considered insubordination? I thought that was something the Army thought not the Navy.

The Navy was similar, if not as extreme.

The Japanese Imperial Naval General Staff wanted Operation FS to go forward first, but Combined Fleet was pushing for Operation MI. After the Doolittle Raid, both the IJA and the IJN could not face the Emperor without MI. But Yamamoto took the diplomatic step of promising the Naval General Staff that following their victory at MI then FS would be next.

Remember, even with Task Force 16 and 17 lost, the USN would still have Saratoga, Wasp, and Ranger to draw on.

To get into the OP, maybe a coup? a TL before the war?

It was army last ditchers who launched coups, not navy peace-makers.

Army ground component was 74K+. AAF was 16K+. Two+ Marine Defense Battalions (~2,500 personnel from the 1st, 3rd & 4th, with other elements on the "outer islands") were also in place. There was also somewhere north of 10,000 USN shore personnel (service troops, mechanics, ship-fitters, etc.) plus crews from the ships in port being repaired/refit, this number varied on an almost daily basis.

There were roughly 15,000 troops on other islands, mainly on Hawaii (aka the Big Island).

Combat aircraft were considerably in excess of 300, the majority being AAF fighters. Had Midway gone badly for the U.S. there were already plans in hand to expand the air component to 350+ fighter and two Heavy Bombardment Groups (these additional resources were distributed elsewhere, both to Australia and the ETO once the strategic picture in the Pacific changed).

It is also not unreasonable to assume that the U.S. would have altered deployment of both the 1st & 2nd Marine divisions if Hawaii was seen to be at grave threat. These were the units sent to the SW Pacific IOTL, it would seem likely that at least elements of one division would be allocated to Hawaii. The pre-Midway plan for the Oahu Army garrison called for an additional full division plus fillers to round out TOE of units in place. This would have brought the Oahu Amy Garrison to over 107,000 combat troops.

About the only division not to be called on would be the Americal Division, as it was needed where it was.

How many troops could the Japanese shift thousands of miles in one go?

Torch was done from North America but that was against far weaker opposition 200,000 odd troops seems logistically impossible to shift soon enough to do more than pile up more bodies on the beaches.

Not to mention that Torch was against Vichy French troops who were not expected to resist for long, if at all.

Torch was also well planned (including having broken enemy codes), had some 'local' (it's less than 2000 km from Britain to Gibratar, at least at minimum distance, Plus, well Gibraltar), and the backing of two major industrial nations.

Plus Axis intervention was going to be initially somewhat haphazard.

Well yes but the Japanese just did things. I think it would fail disastrously but I'm asking whether they would think it had a hope in hell of succeeding if they make a hopelessly overcomplicated plan and throw loads of men and ships into the meat grinder as they usually did.

The feasibility study made (pre-Midway) for an invasion of the Hawaiian islands showed to the Japanese that it was beyond their means. Though how they might have felt after a successful MI and FS is anybody's guess.

This study [1] showed that the Japanese would NOT have air superiority, would be outnumbered on the ground, and could not expect to effectively eliminated Oahu's defensive gunnery as the fleet would be needed against Oahu's air defenses and the USN's remaining fleet units.

1] Source: Costello's "Pacific War"

Japanese Army did a appreciation discussion of attacking the Hawaiian islands. They thought a initial assault force of 5,000 to 10,000 men possible & another 20,000 to 30,000 is sucessive lifts spread over many weeks. [2] They told their naval counter parts they were not much interested. At the time the 'Fiji Operation' was foremost in the mind of senior Japanese leaders. They thought this would cause Australia & New Zealand to sue for peace, and that it would be easy since the Fiji, Samoan, & other islands [3] in the region were lightly defended. They judged a advance force of 5,000 to 10,000 men should be able to accomplish much in that direction. [4]

2]

3] New Caledonia, which as CalBear has described would be a monumental disaster. Fiji and Samoa, along with the New Hebrides and Ocean and Nauru Islands, were either lightly or completely undefended. But they were not the golden prize, as their relatively small size did not allow for the exploitation of major air bases.

New Caledonia OTOH was half the size of Formosa and defended by the well-led [5] and highly trained (in jungle warfare!) Americal Division, a rare Army outfit whose high standards even the USMC respected.

4] They judged wrong.

5] By the future 7th US Army commander Alexander Patch!

Had Yamamoto not presented the Midway operation, or been overruled on it, the Japanese main fleet would have been committed to supporting the Fiji operation.

You'd have to have the Doolittle Raid forced to withdraw without an attack for that to happen.

Thus there would have been four extra carriers and their air groups opposing the USN attack to the Solomons & Guadalcanal. [6] Conversely the USS Yorktown would have been properly repaird/refitted by this time, the Saratoga returned from its repair/refit, & the Wasp not far behind.

I'm not sure of what you mean? What is the timing for this ATL FS operation, and what are the results of TTL's Coral Sea?

Judging from the awsome superiority of the Japanese warrior & combat methods, proven in China, Malaya, Dutch East Indies, ect... the degenerate mongrel US soldiers should be not a problem. Most of that 100,000 would be non combat support units. No better than the Korean labor battalions that accompanied the Japanese army. The fall of Singapore would be a good model for a attack on Oahu

Where are Oahu's water supplies? Do the Big Guns of Oahu only have a 10-30 degree traverse?

The Japanese at no stage of the war possessed the forces it needed to invade Hawaii while maintaining it's over stretched garrisons in the Pacific, Indonesia and China. The logistics of supplying such a force would be a huge stretch and force the Japanese to fight on the other side of the Pacific miles away from their supply bases against what will be a well entrenched American garrison, who will be receiving reinforcements and supply from CONUS (which is closer).

Which is why the IJA said to the IJN "Fuggedaboutit" This is speculating about a post-MI/FS Japan victory scenario.

Depends how much of a battle they have with Midway proper. If it's similar to Wake, then they might decide not to bother, figuring that such a major base that much further away would be impossible to take, and even more so to keep supplied.

Agreed. Though taking New Caledonia is a relative ASB action anyway. The Combined Fleet simply lacks the fleet train needed to lurk in the vicinity of New Caledonia long enough to take the island even if they HAD both the amphib and troops available. CalBear in another thread compared Operation FS to Okinawa. "Staking out goats for the tiger". Except at Okinawa when an Essex class got skunked, there was another to take its place while said skunked Essex went to Ulithi, Oahu, or the CONUS for extended repairs. IJN carriers when hit, if they don't sink, are irreplaceable in the OB. By the time the Taiho comes on-line, the Essexes will be arriving assembly line style.

Though the problem was huge, the core issue wasn't the logistics, it was airpower and the inability of the IJN to attain it. By summer 1942 Hawaii's land based airpower was beyond the IJN carrier fleet's capacity to deal with, while the outer island airfields were all adequately garrisoned meaning that in any offensive the Japanese could only count on seaplane bases to enhance their carriers.

Agreed. And at New Caledonia they'd face the same problem: Conducting offensive amphib operations completely outside of land-based air range.

That's the first time I've ever seen it claimed that the 3 divisions (2nd, 7th, 52nd) earmarked in May 1942 by the IJA for the assault landing totalled only 10,000 men. I thought after reinforcement, it would have been more like 50,000 - 75,000 men.

What's your source?

Maybe it was a typo? Or maybe that represents why the whole idea of invading Oahu {by the time of MI) was rejected by the IJA?

 

[usertron2020]

That entire statement was ripped right from a book called What If? Is that plagiarism?

AH.com is not spacebattles.com, [1] this site is considered more educational than literary. As long as his post is not part of an update by an OP in an ATL, it is AFAIK OK.

1] Plagiarism being spacebattles' bugaboo.

 

[Glenn239]

Where are Oahu's water supplies? Do the Big Guns of Oahu only have a 10-30 degree traverse?

Depends on the battery and the timeframe. Open air batteries (like the 16" guns circa December 1941) as well as the rising mounts had 360 degree fire capacity, but were also vulnerable to attack. Casemated guns had limited traverse. In terms of positioning, the north and south shores had most of the defensive firepower, the east and west coasts much less, (the twin mountain ranges on Oahu formed the main protection from landings here).

Maybe it was a typo? Or maybe that represents why the whole idea of invading Oahu {by the time of MI) was rejected by the IJA?

The 2nd, 7th and 52nd infantry divisions were earmarked for the assault on Oahu by the IJA in May 1942. These orders were cancelled after Midway. See Hawaii Under the Rising Sun.

 

[MattII]

Could a Battleship fire from dry-dock?

 

[Glenn239]

Yes, provided that its magazines were full and it had trained spotters connected by radio or telephone.

Edit - not sure a battleship actually on supports in dry air would fire its main guns. I think it would at a minimum need to be in the water.