Operation Olympic

[Vingilótë]

If the US Atomic bomb project had been delayed or prevented for whatever reason; even just if Einstein's letter is delayed by a couple years or his conscience, then it seems to me that with minimal butterflies, in 1945, Operation Olympic, the invasion of Kyushu, would have opened the American invasion of the Home Islands.

What we know from OTL is that there are a number of reasons that this may have ended badly; for starters, from what I understand, Japan had correctly predicted the intended target of Operation Olympic, and had accordingly allocated the vast majority of their resources and personnel to Kyushu, furthermore, I've also read that other events, such as Typhoon Louise, could easily have had unintended and dangerous consequences.

It is, of course, possible or probable that the Soviet entry to the war would end it in any case, but even so, what would be the immediate result and consequences of the execution of Operation Olympic, with the above and other factors taken into account?

 

[Gurroruo]

If the US Atomic bomb project had been delayed or prevented for whatever reason; even just if Einstein's letter is delayed by a couple years or his conscience, then it seems to me that with minimal butterflies, in 1945, Operation Olympic, the invasion of Kyushu, would have opened the American invasion of the Home Islands.

What we know from OTL is that there are a number of reasons that this may have ended badly; for starters, from what I understand, Japan had correctly predicted the intended target of Operation Olympic, and had accordingly allocated the vast majority of their resources and personnel to Kyushu, furthermore, I've also read that other events, such as Typhoon Louise, could easily have had unintended and dangerous consequences.

It is, of course, possible or probable that the Soviet entry to the war would end it in any case, but even so, what would be the immediate result and consequences of the execution of Operation Olympic, with the above and other factors taken into account?

Well first off hundreds of thousands of deaths. The Americans would push and be bloodily repulsed the first time. After more bombing they would make beachhead. And the Americans would keep pushing and pouring in hundreds of thousands, but the Japanese wouldn't give. If say the Americans invaded before the Soviet entry then the Japanese would keep fighting. The US might take Japan but at heavy losses in the hundreds of thousands. Remember the Japanese people thought of the EMperor as a God, and he was unwillingly controlled by the military. But in all reality it would turn into a far far worse Vietnam.

 

[Matt Wiser]

I did my MA Thesis on OLYMPIC, and managed to get the actual planning documents (Army Forces Pacific, CINCPAC, and Amphibious Forces Pacific), along with The Reports of General MacArthur. Kyushu would've been secured in about 70 days with 70,000 to 85,000 U.S. and Allied casualties, and about 300,000 Japanese casualties. The Japanese defenses, though formidable, had one major flaw: Hold on the beaches, defend to the death, and no retreat. The same thing tried on every Pacific Island until Pelileu, Luzon, Iwo, and Okinawa, and failed every time. Then, it should be noted that in some areas of Southern Kyushu, Japanese defenses were incomplete, and opposite two beaches in Southern Kyushu (West side of Kagoshima Bay), hadn't even been started. In addition, shortages of fuel, ammunition, motor vehicles, etc. hampered the Japanese defense plan (KETSU-GO), from the get-go. Two of the divisions assigned to defend Kyushu had only been raised in June '45, and hadn't received their full equipment allotment, and one division (146th ID) only had rifles for ten percent of its soldiers.

OLYMPIC would've been bloody, with fighting comparable to Okinawa and Luzon, but the Japanese would've been overwhelmed, and would likely have surrendered prior to CORONET: the attack on the Kanto Plain set for 1 March 1946.

See John Ray Skates' book, The Invasion of Japan, Norman Polmar and Thomas Allen's Code-Name Downfall, and The Reports of General MacArthur. They lay things out very well.

 

[ObssesedNuker]

Also: the Soviets seize Hokkaido.

 

[mcdo]

If you just want to talk about what Olympic would have been like had it happened, that's fine of course. But since you specifically mentioned a delayed US atomic weapons project as your PoD, I do want to mention that the US Strategic Bombing Survey, and quite a few various high-ranking American military officers from the Pacific, were of the opinion that even without atomic weapons, the Soviet entry into the war, the continued bombing, and (in my opinion most importantly) the blockade would have resulted in an unconditional surrender from Militarist Japan prior to the Nov 1 planned start date of Olympic.

 

[Matt Wiser]

A delayed atomic bomb is the POD for the book Lighter Than a Feather, by David Westheimer, which is a "What-if" novel of OLYMPIC. However in his TL, the Soviets do attack Manchuria, but the Japanese fight on.

 

[SunilTanna]

I created the website http://www.operationolympic.com about this exact topic (as well as http://www.operationcoronet.com/). Things like official casualty estimates etc., are all on there.

One thing however that has since occurred to me that there could easily end up being no organised Japanese high command (they might all be killed, split into factions, etc). In that case the end would be very messy, with some groups surrendering, others fighting to the last man, and others hiding out in the woods or mountains to continue resistance indefinitely. Eventually most would die or give up, but there might a few who continue low level fighting for years.

 

[Matt Wiser]

Re: Soviet invasion of Hokkaido...they didn't have the amphibious lift needed, and Soviet planners said in the '90s that detailed plans only existed in Stalin's mind. A Hokkaido landing would've awaited the conclusion of the Kuriles and Sakhalin (Karafuto) operations-and the former was turning out to be a bloody mess, as the Soviets nearly got kicked off one of the islands they landed on.