Operation Downfall - The Invasion of Japan

Discussion in 'Alternate History Discussion: After 1900' started by Chilperic, Aug 14, 2008.

  1. Chilperic Banned

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    Introduction

    In 1945, Japan was prepared to fight its final battle and make its last stand against the Allies. Having been driven back from the Pacific after 4 years of bitter conflict, defeated at Midway, Guadalcanal, New Guinea and eventually even Iwo Jima and Okinawa, both part of Japanese sovereign territory, Japan readied itself for the final onslaught.

    The Imperial Japanese Navy had lost all its aircraft carriers, and was a shadow of the fleet which had gone to war in December 1941. The Marianas 'Turkey Shoot', the fighting at Leyte Gulf, had wrecked the IJN. This left 23 destroyers and two cruisers to face the American invasion. They had now prepared new tactics such as human torpedoes, midget submarines and the Shin'yo suicide boat.

    The Japanese Air Force was now resorting to desperate measures, including the kamikaze (divine wind). This had been used to devastating effect; in the battle of Okinawa alone, 26 American ships were destroyed by these attacks.

    Japan itself was running out of oil and had only limited resources to fall back on. Being cut off from raw materials by a US trade embargo was one of the reasons Japan attacked the US.

    Additionally, there was the threat of chemical weapons; they had been used by Japan before in China.

    Meanwhile, the US had attempted to test the atom bomb in July but the detonation was too weak and the test was considered a failure. The scientists on the program told Truman that they would have to fix the problem, and this would be done by February 1946. So the Allies prepared for Operation 'Downfall', the invasion of Japan.

    The first part of the operation would involve a landing on Kyushu, known as Operation Olympic. The objective of this was not to capture the island, but to secure airstrips for the bigger attack: on Tokyo itself, known as Operation Coronet. The main operation was set to begin on 1st November, known to historians as X-Day.
     
    Last edited: Aug 16, 2008
  2. oudi14 oudi14

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    OK, so where do we go from here? If you are looking for an interesting read, check out 'the burning mountain' by AlfredCoppel. This dealt mainly with Operation Coronet, which began March Ist, 1946. Now as to what it actually would have been like; I suspect that Operation Olympic would have proven so bloody that Coronet would never have happened. Many speculate that the Japs would have surrendered anyhow, even without the bombs, but I am convinced that Olympic would have gone ahead; there were too many fanatics in the Japanese government and millitary.
     
  3. Chilperic Banned

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    Olympic - Preliminary Invasion, October 25 to October 28

    October 25 (X-7) - The islands of Koshiki Retto come under sustained shore bombardment from the battleships of William Halsey's Third Fleet including the Missouri. Several ships also bombard smaller islets in the region that are designated for attack. Little do the Americans know that Japan has evacuated large amounts of their garrisons on these islands already.

    Meanwhile, a deception plan know as Pastel has been captured by the Japanese. This shows that the US plans to attack Taiwan and Japanese occupied China in an attempt to encircle Japan.

    October 26 (X-6) - The bombardment continues. Several kamikaze attacks result in the loss of 4 destroyers. Attacks also continue on mainland Japan with high explosive shells doing devastating damage to enemy fortifications.

    October 27 (X-5) - Elements of the 40th Infantry Division land on the islands of Ujishima, Kusikakishima, Kuroshima and Kuchinoerabujima. The former two are captured with only 7 deaths, all due to mines; the islands had been completely abandoned. On Kuchinoerabujima, resistance is also light, with a small garrison of Japanese being eliminated by noon. Kuroshima, however, proved to be more difficult. As the infantry landed, heavy machine guns opened up on their positions and fighting is fierce, although by the end of the day American forces have secured 80% of the isle. Only 48 POWs are taken, and all the garrison commanders are found to have either died in battle or committed harakiri.

    Simultaneously, the 158th Regimental Combat Team lands on Tanegashima and faces relatively tough resistance but ultimately defeats the Japanese garrison. Approximately 400 Americans are reported dead by the end of the day.

    Kamikaze attacks have continued with 7 cruisers and destroyers sunk and 4 more damaged. Several midget submarines are reported to have been sunk.

    October 28 (X-4) - 40th Infantry Division lands on Koshiki Retto. Resistance varies: on Tairashimo, US forces landed on Beach Headlight unopposed and reported no Japanese soldiers on the isle. Shimo Koshiki proved harder, with the garrison holding out to the last man. Air support arrived in the form of the US 8th Air Force commanded by Jimmy Doolittle. By the end of the day, Shimo Koshiki was secure.

    Kami Koshiki was relatively well fortified and US forces had a tough time wiping out the garrison, especially on Beach Gearshift where 65% of the US casualties on the island were reported. However, the forts were cleared out with air support and grenades by 1800.

    Airstrips were now being constructed on the captured islands and on some, even radar. Meanwhile, the US fleet decided to lure the Imperial Japanese Airforce into confrontation....
     
  4. CalBear Your Ursus arctos californicus Moderator Moderator

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    How, one wonders, did Truman come to the conclusion that the Olympic & Coronet would be less costly than the use of the atom bomb? Surely not for Allied troops, and almost as surely for the Japanese.


    A few (of MANY) samples

    JCS Joint Strategic Survey Committee

    Secretary of War Stimson memo to President Truman (Note: The U.S. at the time used the figure of 354,000 battle casualities for Red Army losses in taking Germany)

    US Army Military Intelligence Division and Medical Corps



    And probably the classic illustration of what the U.S. Army thought was going to happen if Operation Downfall occurred


    http://home.kc.rr.com/casualties/
     
  5. CalBear Your Ursus arctos californicus Moderator Moderator

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    Don't forget the Typhoon that struck the amphibious ships marshalling area this week of 1945.

    An Honest-to-God kamakazi!
     
  6. burmafrd Well-Known Member

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    With the info we had at the time, and the very recent experience on IWo Jima and Okinawa, there is no way that anyone with any kind of brain thinks that dropping a couple of bombs -even big ones- is going to be worse then invading the Japanese home islands. Since Truman admited that at the time he just thought they were bigger bombs and that is all, I cannot see how he comes to that conclusion and ok the invasion rather then use the bombs.
     
  7. Typo Banned

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    And to be fair, the existing american firebombing of Japanese cities were causing far more casualties anyways.
     
  8. Amerigo Vespucci Not lurking since Dec. 2002

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    Allow me to point you to this thread, in which I lay out my timeline of events.
     
  9. Markus Banned

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    Actually the Americans f...ing hate the Japanese and had no problems at all killing almost any number of them to save their own troops. So that ain´t gonna happen. Just like Olympic and Coronet IMO ain´t gonna happen, because the Japanese wont´t last that. In august the Soviets will wipe out the Japanese presence in Manchuria and Korea, followed by an invasion of Hokkaido in September.
    Note that Olympic was planned for November and Coronet for March 46.

    By that time Japan has either surrendered or is mostly occupied by the Red Army.

    A few words about the utterly overpessimistic casualty guesstimates: Kyushu, the target of Olympic was seemingly very heavily defended indeed. But that came at the expense of everyplace else, including Honshu, so some in the US military siggested bypassing Kyushu and going straight to ill-defended Tokyo.

    On top of that almost all of the defenders were recently drafted(=untrained) and laccked virtually every weapon needed to fight. They had just 50% of the rifles, 25% of the machine guns and 75% of the artillery and AT-guns their ToE called for. A ToE that as "light" on heavy weapons in the first place.
     
  10. CDurham Well-Known Member

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    True, and while the scientists knew there would be SOME radiation they had little idea about fallout. In fact, since Truman thought its just a bigger bomb, what if he OK's their use as a tactical weapon (read beach clearence device) . It was recomended by Col. Lyle E. Seeman that American forces not enter the area hit by the bomb for at least 48 hours. (we would have had 7 by X-Day) Of course, this doesn't mean they can't land on either side of whatever this "area" is.
     
  11. CalBear Your Ursus arctos californicus Moderator Moderator

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    True and true.

    Not quite as sure about this point (at least the occupation), mostly because I see the Japanese folding once Hokkaido is being overrun.

    Even MacArthur, the eternal optomist when it came to losses, was leaning toward going straight for Honshu. While not the 2,000,000+ predicted using the "Saipan formula" Allied (primarily American) losses would still have been huge invading Kyushu. The Jpanese were primed there, with enough cannon fodder available to make the place damned costly.

    What may have been underestimated is the Japanese total casualties once civilians were calculated. With the starvation that was already rearing its very ugly head considered, along with ongoing fire bombing of every Japanese population center larger than a hamlet, Japanese civilian death tolls could have been beyond belief.
     
  12. merlin Well-Known Member

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    After the Japanese are 'wipeout' who re-populates the 'home islands'!?
     
  13. Markus Banned

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    No need, they fold loooong before any kind of wipe-out takes effect. Had they been as determind to fight to the last men, woman and child as it seemed, they could have done so even after the nukes.

    The way I see it they needed one final big kick in the nuts and IMO a non-nuclear one would have worked too, like the one the Red Army administed in Operation August Storm.


    @CalBear: If a total blockade combined with massive air raids would have been conducted into 46 massive civilian casualties would have been the result, but Japan can only last that long if the USSR stays out of the war. And the USSR had no intention of doing that, given at least four decades of mutual enimity.
     
  14. rudebadger Well-Known Member

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    I see any invasion of the Home Islands happening only if we can't get the A-bomb working. Even then it may not happen. LeMay was getting great, if horrific, results with the fire-bombing of the cities by August. And Japan's imports were being squeezed tighter month by month by the USN's submarine attacks and roving carrier air strikes.

    Truman and the rest might have given these operations a year to see if they could weaken or break the Japanese before any type of invasion were attempted.
     
  15. Chilperic Banned

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    Hmmm, doesnt seem too positive :( Anyway, I'll continue, but I could do with help regarding certain aspects; it is my first TL after all.:rolleyes:
     
  16. bm79 Citoyen Louisianais

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    Hey dude, take heart. An Invasion of Japan timeline is a good idea. I think that you might have to make the POD a failed, or at least less-than-overwhelming Trinity test, though, to make it more feasible.

    Perhaps some technical snafu occurs that leads to an explosion of 1kT or less. The technology would still be proven viable, but in need of more tweaking. Truman in this situation would still work out a deal with Stalin at Potsdam for a joint attack on the Japanese, and the planned invasion would go ahead. The main invasion of the Kanto wasn't planned until March 1946, and the war could still be ended by the nuke after "Olympic"...
     
  17. Enigmajones Ours Is The Fury

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    I think we would have a Korea situation in Japan
     
  18. burmafrd Well-Known Member

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    For those thinking the japanese would have quickly collapsed, you need to do some remedial research. even after the 2 bombs had been dropped, there were several on the Imperial General Staff who wanted to keep fighting. One even hypothesized that we might only have a few bombs (he was right). After the decision was made, pushed by the Emperor, some young fanatics were planning to steal the tape and keep fighting no matter what. There were others who were thinking of crashing the Missouri once she reached Tokyo Bay. If the decision had been made to keep fighting, it would have been horrendous and bloody. Just because you are not proficient in marching and saluting, does not mean that you cannot sit in a bunker and fire a rifle out a slit and hit someone.
     
  19. CalBear Your Ursus arctos californicus Moderator Moderator

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    True. (Although, truth be told, the Japanese were also short of rifles.)

    The ease of mounting a defense, especially one where you really do not expect anyone to survive, from well prepared positions, is one of the reasons the entire Olympic landing operation was under review. As the Intel piled up it was increasingly clear that the Japanese had moved everything they could to Kyushu and that they also lacked the fuel and transportation net to move any of it back to Honshu. There was a serious movement in the Allied JCS Planning Group to go straight to Coronet, or, as an Olympic alternative, invade Shikoku and set up the air bases planned to support the last push onto the Kwanto Plain there instead of the increasingly unattractive Kyushu.

    Even without the Bomb, the odds are 60:40 that the invasion of Kyushu wouldn't happen as originally planned. This likelihood is increased greatly by the fact that the October 8/9, 1945 Buckner Bay Typhoon would have crippled a significant portion of the amphibious force (with God alone knows what sort of positive effect on Japanese morale) and pushed any Kyushu Invasion into January at the earliest. Even without any Soviet involvement in Manchuria or Korea, by January of 1946 Japan would have been half dead from stravation. By March it WOULD have starved to death, at least in the case of large segments of the urban population (those who the B-San hadn't burned to cinders in what promised to become daily air raids) and a rather surprising percentatage of the rural population.
     
  20. DuQuense Commisioned Officer CSN

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    some sugestions

    The weather people all expected the Typhoon to safely pass Okinawa a hundred miles out to sea.
    Then it made an abrupt turn and Lunged at the Island.

    The speculation is that disturbances in the upper astrosphere steering currents caused by the Bombs, caused this.

    No bombs-- the jet stream is undisturbed and the Typhoon misses Okinawa.

    POD 1943, New Mexico

    Oppenheimer was overseeing the radiation tests while several others where --Tickling the Tiger-* Suddenly one of the Scientists stumbled and the two pieces of Uranium where jammed together.
    Instancely the Geiger counters started shrilling, the tests were abandoned for several weeks, while Oppenheimer and the other Scientists recovered from the Radiation Burns.

    The project would be farther delayed when in mid 1944 Oppenheimer and several others died from Radiation Poisoning.

    But by late Novembre 1945, they were ready for the first test bomb. With a couple of production bombs expected early in 1946.


    * not sure if my phase is correct, but it involved slowly pushing two pieces of material towards each other on measuring the increasing Radiation.
    IIRC they used those pool sticks with the Finger thingy.

    The Fate of both Japan and Korea were sealed at the Berlin conference in Septembre 1945, When the three leaders agreed that Russia would concentrate onmopping up the Japanese troops in Korea, while the Americans and British would concentrate on Japan and --Indonesia.



    Remembre Indonesia declared it's independence -- as a Japanese ally --on Septembre 1st 1945.
    It was backed by a newly established Indonesian Military, and the remains of the Japanese troops on the Islands.


    This is also the around the time that Vietnam under Uncle Ho chi Mien declared Independence.
    With three division of Vietnam troops, well supplied with captured Japanese Equipment, and backed by the OSS.