Typhoon "Louise" and Operation Downfall....

Okay, so it is accepted wisdom that the Typhoon that unexpectedly struck Okinawa on October 9, 1945 (nicknamed Typhoon "Louise") would have caused a 45-day delay in the invasion of Kyushu had the war not ended in August 1945.

I've wondered about this for a little while now, because of information like this map and this map which show that for the invasion of Kyushu (Operation OLYMPIC, later renamed Operation MAJESTIC in August 1945) of the 14 divisions planned for use (12 assault and 2 follow-up) only ONE division was to be mounted from Okinawa while 1 division was to be mounted from the Marianas, 9 divisions were to be mounted from the Philippines and 3 divisions were to be mounted from Hawaii. Furthermore there were 3 divisions in reserve for MAJESTIC with 1 division based in the Ryukyu Islands (essentially Okinawa) and 2 divisions based in the Philippine Islands.

Thus out of the 17 divisions available for MAJESTIC only 2 divisions were based in or to be mounted from Okinawa.

How then could there really have been a 45-day delay in the planned launch of MAJESTIC if there were 15 divisions available for use and not based in or mounted from Okinawa and MAJESTIC required 14 divisions?

Is it that the "US analysts" referred to who made this assessment didn't know what they were talking about? Or that they were referring to instead a 45-day delay in the launch of the division that was to be mounted from Okinawa to invade southern Kyushu instead of to the entire operation?
 
Hm, without looking anything up about it i always thought the threath of the Typhoon was not because it was to hit just Okinawa, but also hit Kyushu later on. That, would have been devastating enough for invading troops.

However, the most important part of it all i think is the airpower mostly came from Okinawa as that was the only place close enough for short-range bombers and fighters to reach Kyushu(i believe that was why the attack on Okinawa was carried out as well, to provide an airbase close to the japanese home islands). If a typhoon hits, no plane will get off the ground and the invading forces will be without much needed air support. The Japanese on the otherh ands will be able to send all their kamikaze planes from the North to the landing forces, seriously endangering the invasion.

A typhoon is a storm of a very large area, any ships caught in it will be submitted to very heavy beating. US carriers won't be able to launch their planes either, nor will any battleships be able to support landing troops with shore bombardments. So any ships coming from the Phillipines would have to go around the storm(The Typhoon come from the East, just over the Pihllipines making it impossible for ships from the Phillipines to cross it)... Highly unpractical if not impossible to carry out a successful landing.
 
Hm, without looking anything up about it i always thought the threath of the Typhoon was not because it was to hit just Okinawa, but also hit Kyushu later on. That, would have been devastating enough for invading troops.

But the typhoon lasted from October 2 to October 12, 1945.

Operation MAJESTIC was planned for November 1945.

So the typhoon would not have affected any invading troops at all since the invasion wouldn't have occurred yet.

However, the most important part of it all i think is the airpower mostly came from Okinawa as that was the only place close enough for short-range bombers and fighters to reach Kyushu

Hmm...perhaps that is it, but I have noticed that all the accounts about the typhoon's effects on an invasion seem to centre around the shipping damaged in Buckner Bay and not on the aircraft stationed on the island. But again, given that only one division was to be mounted from Kyushu and that the Typhoon occurred almost a full month before the expected invasion date I'm still having trouble seeing how even damaged shipping in Okinawa in an ATL where Japan didn't surrender in August 1945 could have greatly affected the invasion unless it was that all the invasion shipping was supposed to be concentrated in Okinawa from October (which makes it difficult to see how the troops based in the Marianas, Hawaii and the Philippines would get to Kyushu) or unless the invasion was intended to occur in October.

(i believe that was why the attack on Okinawa was carried out as well, to provide an airbase close to the japanese home islands).

Yes, that is correct.

If a typhoon hits, no plane will get off the ground and the invading forces will be without much needed air support.The Japanese on the otherh ands will be able to send all their kamikaze planes from the North to the landing forces, seriously endangering the invasion.

A typhoon is a storm of a very large area, any ships caught in it will be submitted to very heavy beating. US carriers won't be able to launch their planes either, nor will any battleships be able to support landing troops with shore bombardments. So any ships coming from the Phillipines would have to go around the storm(The Typhoon come from the East, just over the Pihllipines making it impossible for ships from the Phillipines to cross it)... Highly unpractical if not impossible to carry out a successful landing.

True, but as I pointed out before the typhoon would not affect the army air force's ability to provide air support because the typhoon would have occurred and dissipated almost a full month before the invasion. So the landing would not be affected by the typhoon and the US carriers would also not be affected by the typhoon.
 
There where tropical storms forecasted in November and December as well. Not typhoon, but weather bad enough that planes won't be able to take off.

At around January skies would have been more clear.
 
There where tropical storms forecasted in November and December as well. Not typhoon, but weather bad enough that planes won't be able to take off.

At around January skies would have been more clear.

Sure, but we actually know what the weather was like in November and December 1945.

In November and December 1945 there were no tropical storms around Okinawa or southern Kyushu so we can forget about the idea of planes not being able to take off due to tropical storms in November and December. There was one tropical storm that did occur around November 1-4, 1945 (Tropical Storm Marge) and it did hit the Philippine Islands, however the fighter based air support was expected to come mainly from Okinawa not Luzon. Given the track of that Tropical Storm though and its strength I don't see how it would have effected a 45-day delay in Operation MAJESTIC though.

I would still like to know if anyone has any idea where this 45-day delay estimate in the invasion really came from and if it was meant to refer to the entire invasion or just the role of the division that was to be mounted from Okinawa.
 
Yes, but they didn't. Thats the whole point i think.

I can look some stuff up about it later maybe.

Okay, you missed it. It doesn't matter if they didn't know at the time. The operation was planned for November 1945. When the date was set the planners themselves already knew typhoons would be a possibility. So the planes are only going to be grounded if there was a typhoon or tropical storm around Okinawa or Kyushu. But as we know there was no tropical storm around either island in November, so we can literally forget about that thread of discussion.

Again, I would like to get back to the original question.
 
OLYMPIC was scheduled for 1 November 45. Assuming the war continued, with Typhoon Louise hitting Okinawa, the delay would likely have not been substantial: a postwar Pentagon Staff Study done in the 1960s (and repeated in 1985) estimated a two-week delay. (see John Ray Skates' afterword to the reprint of Lighter Than a Feather-David Westheimer's what-if novel of Operation OLYMPIC)
 
OLYMPIC was scheduled for 1 November 45. Assuming the war continued, with Typhoon Louise hitting Okinawa, the delay would likely have not been substantial: a postwar Pentagon Staff Study done in the 1960s (and repeated in 1985) estimated a two-week delay. (see John Ray Skates' afterword to the reprint of Lighter Than a Feather-David Westheimer's what-if novel of Operation OLYMPIC)

Thank you!

That's interesting. It makes me further question how accurate Giangreco's articles and books about the invasion of Japan (such as Hell to pay) are.

I first noticed that in his book on the topic he basically dismisses the Soviet's planned invasion of Hokkaido and uses the supposed fact that the Soviets wouldn't have had any air cover for any troops that they could land there. Which of course is rubbish since the Soviets fielded fighter aircraft at the time that had a combat radius that could cover at least western Hokkaido from bases in the Soviet Far East, let alone from any air bases captured in southern Sakhalin....

I then noticed that in his book he makes the rather questionable assumption that once the Americans landed in southern Kyushu, they would have been drawn up past their intended stop lines (running through a range of mountains) to pursue the retreating Japanese towards their planned redoubt (which would have been found in the northern third of Kyushu) along the western and eastern coasts of the islands. Quite why the Americans would do something this stupid is never really adequately explained but of course doing this action would result in even more American casualties.

It now makes me wonder if he has a slight bias towards the idea that lots of Americans simply had to die in an invasion of Japan and so leans towards concepts that would naturally result in increased casualties regardless of whether or not such concepts have grounds in any historical precedence or actual documentation or whether such concepts are the result of old, faulty assumptions (such as the analysts in 1945 who supposedly predicted a 45-day delay after Typhoon Louise if the invasion was still supposed to occur) even if newer research is out there (and in this case, that kind of research - Pentagon Staff Studies done in the 1960s and 1985 - has been around long enough that I don't see how he could have missed it if he spends so much time researching this topic).
 
Well, I did my MA Thesis on the whole invasion: not just OLYMPIC, mind, but CORONET as well.

Sixth Army would've gone no further than the Sendai-Tsuno line, as all of OLYMPIC's objectives would have been met. The object of OLYMPIC is not to seize the whole island, but to secure the ports and airfields (and space for building more of the latter) to support the next operation: CORONET.

Now, if CORONET had failed to induce Japan to surrender, an amphibious operation aimed at Northern Kyushu was a possiblity: ten days after the TRINITY A-Bomb test, the JCS circulated a memo on post-CORONET Operations. Northern Kyushu, the area around Sendai in northern Honshu, Ise Bay-Osaka, and Hokkaido were all candidates, with a target date of 1 July 1946 for the first operation. Keep in mind, these were very preliminary discussions, which the events of Aug 1945 rendered irrevelant. (See The Invasion of Japan: Alternative to the Bomb, by John Ray Skates for more on the invasion: I found it very useful when I did my Thesis)
 
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