A Coup In The Night: Hirohito Deposed In 1945

Would to the Soviets have invaded Hokkaido in this scenario? As much as I know, the Soviet Navy in the Pacific lacked the proper amphibious assault capability to pull off for this one.

en.wikipedia.org/wiki/Project_Hula#Soviet_lack_of_adequate_naval_capability

It took almost a month after the Japanese surrender to finish occupying the Kuriles and landings were conducted in October of 1945; they simply lacked the capacity invade Hokkaido in 1945 and if they tried it would've been a blood bath as the Japanese had ~100,000 troops and 450 aircraft stationed there.

We don't have to guess whether the Japanese could concentrate their forces; they already had by August. 

IGHQ had been stockpiling aviation fuel for months in preparation for the invasion, with total inventory being 1,156,000 barrels by July of 1945. Much the same had been done for pilots, with IJA having 2,000 pilots with at least 70 hours of flying time while the IJN had 4,200 on hand who were considered sufficiently trained for night or low light missions; given the type of challenges those conditions presented, that means they were well trained. Overall, when the Japanese formulated KETSU-GO starting in July of 1945, the plan called for 9,000 aircraft to be brought to bare against the invasion fleet. Contemporary to this, the Japanese inventory already contained 8,500 ready planes and IGHQ expected another 2,000 by the fall. When the Allies conducted a census in August following the surrender they found 12,684 aircraft of all types in Japan, suggesting that IGHQ's estimates were spot on for 10,500 aircraft by November. As for planned uses, of the 9,000 to be used in KETSU-GO, kamikazes were to comprise 6,225 of the total.

That last bit is perhaps the most important, as experience at Okinawa had shown that a 6:1 ratio existed in the expenditure of kamikazes to achieve a successful ship sinking. Japanese planning held, and U.S. estimates agree with them, that they believed in the initial 10 days of the invasion they could sink at least 500 transports out of the expected 1,000 the U.S. was bringing for the attack. This would've amount to the loss of about five divisions and much of the logistical network, crippling the invasion before it even stormed the beaches. There is every reason to believe this would've worked, as the Japanese would've enjoyed several advantages they didn't have at Okinawa, such as:

• The mountainous terrain meant that Japanese attacking aircraft would've been shielded from radar detection almost until they were right up on the fleet. At Okinawa, the U.S. had been able to deploy destroyers as pickets dozens of miles out but that wouldn't have possible here because the invasion fleet obviously had to be closely anchored off Japan.
  
• The "Big Blue Blanket", which was an Anti-Kamikaze tactic devised by the U.S. during Okinawa, involved masses of fighters kept aloft and being fed data by the picket ships. However, this would've been impossible to counter the Japanese here, as the U.S. was only bringing 5,000 total aircraft from the Far Eastern Air Force in the Ryukyus and the carriers of the 3rd and 5th Fleets. The problem, as outlined by Giangreco, was that U.S. planning called for TF-58 with its 1,900 plans to be 600 miles to the North attacking targets in Honshu instead of supporting the 7th Fleet. This left just two carrier groups to provide a combat air patrol for the fleet, which means that American fighters would've been outnumbered by the Japanese by about a staggering 10 to 1. In other words, even if every American fighter pilot became an ace during those first 10 days, thousands of Japanese aircraft would've still broken through.
  
• The Japanese had 60 airfields on Kyushu (with more being constructed, 75 expected by D-Day) and the aforementioned fact of short distances to target meant that mechanical issues, a problem that plagued kamikaze operations during Okinawa given the hundreds of miles distance from Japan to the island, would not have been anywhere near as prevalent.

Further:

To oppose the 700,000 to 800,000 soldiers and Marines of the Sixth Army (of whom only about 600,000 would be actual "ground troops"), the Japanese Imperial Army planned to gather 900,000 men at the conclusion of their mobilization (already in its final stage), to be bolstered to 990,000 during the actual invasion through the transfer of 4 more divisions across the Shimonoseki strait from Chugoku. This does not even consider the large amount of Naval personnel present, who, as in the Philippines, Okinawa, and elsewhere, would have been inevitably pressed into service. As already mentioned, the topography of Japan and capabilities of the Allied forces meant that it was easy for IGHQ to guess the location, timing, and approximate strength of the expected Allied blows. Rather than the three-pronged flanking attack against only a portion of the Japanese Army anticipated by US planners, the Sixth Army was essentially going to make three frontal assaults straight into the teeth of an enemy that would have outnumbered it roughly 2 to 1 on the ground. The 57th Army in south-east Kyushu alone, for instance, comprised some 300,000 men, 2,000 vehicles, and 300 tanks. By itself, this corresponds almost completely to what General MacArthur initially believed would be present in all of Kyushu by November 1945.​

Unlike in other regions of Japan, the Sixteenth Area Army's preparations in Kyushu were well-progressed by the time of Japan's surrender in August: even though stocks of equipment and ammunition were strained by the rapid expansion of personnel strength, all forces were to be fully outfitted by October 1945 (and the Kanto Plain's Twelfth Area Army - by spring 1946)[11]. Because of this, American troops, badly battered by Japanese bombers before disembarkation at sea, would have landed ashore against an enemy fully expecting them and present in much greater strength than anticipated; indeed, in greater strength than had been previously encountered anywhere during the Pacific War. In the close-in, mountainous country, where US advantages in mobility and firepower are minimized, the combat would have taken on a savage, personal nature, conducted "at the distance a man can throw a grenade." Although "permanent" coastal fortifications were relatively sparse, there was no 'crust' to be broken (like with the German Atlantikwall), but a solid core spanning the entirety of southern Kyushu. American forces, who had no preconceptions of any of this, would have thrown themselves into a meat grinder. Even if they managed to overcome the initial defenses and withstand the enemy's counterattacks, the presence of Japanese forces dug into the mountains of northern Kyushu would have presented a constant danger through to the end of hostilities, as was the case in Italy and Korea.​


There is one more important factor to consider: the weather. As mentioned previously, Typhoon Louise was set to batter the staging grounds on Okinawa in October, scarcely a month before the planned invasion. The damage done by this was estimated to set the landings, originally scheduled for 1 November, back to December at the earliest, which would not only have required a whole new analysis of weather and other environmental conditions but also would have afforded General Yokoyama's defenders even more precious time to prepare. Incalculable too would have been the psychological boost to the Japanese as a whole at the sight of the "divine winds" coming to their aid once again, and the damages done as a result of fighting elsewhere in Asia and by Japanese atrocities against civilians and prisoners of war (POWs). Further storms in the spring of 1946 (Typhoon Barbara) would have presented additional challenges.​

To quote Major Arens' conclusion:​

"The intelligence estimates of the Japanese forces and their capabilities on Kyushu, for Operation Olympic, were so inaccurate that an amphibious assault by the V Amphibious Corps would have failed ... If Operation Olympic had been executed, as planned, on 1 November 1945, it would have been the largest bloodbath in American history. Although American forces had superior fire power and were better trained and equipped than the Japanese soldier, the close-in, fanatical combat between infantrymen would have been devastating to both sides."​

To put this into context, in April of 1945 JCS adopted ratios based on the experiences sustained in both Europe and the Pacific, with the Pacific one being 1.95 dead and missing and 7.45 total casualties/1,000 men/day. Applying that to OLYMPIC results in 878,453 killed or missing and 2,481,233 wounded, or 3,359,686 in total. Take in note, this was before the absolute bloodbath which was Okinawa, even.
 By Okinawa, those Japanese were inflicting about 1:1 losses on the Americans; this is how we got MacArthur's staff calculating the 1:1 parity in the "Sinister Ratio". I ask the audience to, irrespective of anything else, consider what happens when you land 700,000 Americans against 900,000 Japanese at a 1:1 casualty ratio. Basic math tells the story, I rather think. This estimate was based solely on regular IJA forces, and is applied to both OLYMPIC and CORONET. Their estimate did not account for IJN or IJAAF personnel pressed into service nor the civilian militias to be raised.....

As for the landings themselves, to quote Gianreco again:

"Juxtaposed against Japanese efforts are the tactical intelligence analyses produced by the U.S. Sixth Army targeting Kyushu—both immediately before the dropping of the atom bombs and several months later, when, with American “boots on the ground,” direct examination was possible of Japanese defense preparations. U.S. personnel were stunned at the scale and depth of the defenses. The Japanese had, to put it bluntly, “figured us out,” said one officer. Chillingly, a highly placed member of the Imperial Army staff told the Sixth Army’s Intelligence chief not only that they expected the initial invasion to be launched on Kyushu in October 1945 but also that they knew the precise locations of the landings.​

Instead of a grinding war of attrition, the U.S. military had hoped for a less costly battle of maneuver, but both the interrogations and the layout of the Japanese defenses indicated that this had not been in the cards. Moreover, the Japanese had expanded their forces on Kyushu far beyond anything imagined by U.S. planners. While neither the highly perceptive positioning of the Japanese defenses nor the increase in forces were apparent before Truman, Stimson, and Marshall left for the Potsdam Conference, by the third week in July it finally became alarmingly clear that a Japanese buildup of stunning proportions had been accomplished right under the noses of U.S. intelligence and was continuing at a rapid pace with “the end not in sight.” Meanwhile, American preparations for use of atom bombs against four specially chosen cities continued apace and the Japanese leadership chose to ignore warnings issued by the Allies at the conclusion of the conference.​

General Marshall, who by now had returned to Washington and been made fully aware of activities on Kyushu, could not assume that the fanatical Japanese would surrender even when atom bombs were raining down on their cities and the Soviet entry into the war dashed their hopes of a negotiated settlement. An examination of alternative invasion sites for Kyushu had been launched when the scale of the Japanese troop buildup had become evident, but both the chief of staff and his commander in the Pacific, Gen. Douglas MacArthur, agreed that none of the sites were adequate substitutes. U.S. leaders were encouraged by the official Japanese government inquiries initiated after the dropping of the first two bombs and Soviet invasion of Manchuria, but optimism that the war might soon be over vanished. Communications had suddenly stopped, and it appeared that Japanese intransigence or indecision was about to scuttle peace efforts.​"

Also, the idea starvation was imminent is a myth that has been debunked since the time of the Japanese surrender. Postwar surveys by both American and Japanese experts concurred that it was not going to happen and the modern research backs it up. To quote Gianreco:

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The potential problems relating to keeping the population of occupied Kyushu fed and relatively healthy during an invasion, however, paled in comparison with those faced elsewhere in Japan after the surrender, and began as early as the winter of 1945–46. Agricultural experts within the U.S. Military calculated in 1944 that there would be enough food available to sustain the population on a subsistence level but had correctly foreseen that “the possibility of localized famines beginning within the first few months of 1946 was a very real possibility.” 15 Some factors, such as the willingness, or unwillingness, of Tokyo and the prefectoral governments to feed millions of “excess mouths” not directly contributing to the war effort, could not be known. U.S. military and civilian officials privy to Magic intercepts duly took note, however, that the anguished warnings by the Japanese ambassador to Moscow, Sato Naotake—including that if the fall 1945 harvest failed the nation would face “absolute famine”—were disdainfully rejected by his superiors. 16 It was also clear that a disruption of the rail system by U.S. air power plus the growing number of refugees would likely collapse the system and that “we’d eventually have to pick up the pieces.” 17

Some today assert, in effect, that it would have been more humane to have just continued the conventional B-29 bombing of Japan, which in six months had killed nearly 178,000 people and displaced or rendered homeless more than 8 million, than to have dropped the atom bombs or launched an invasion. 18 They also imply that the growing U.S. naval blockade would have soon forced a surrender because the Japanese faced imminent starvation. U.S. planners at the time, however, weren’t nearly so bold, and the whole reason why advocates of tightening the noose around the Home Islands came up with so many different estimates of when blockade and bombardment might force Japan to surrender was because the situation wasn’t nearly as cut and dried as it appears today, even when that nation’s ocean supply lines were severed. 19

Japan would indeed have become “a nation without cities,” as urban populations suffered grievously under the weight of Allied bombing, but over half the population during the war lived and worked on farms. 20 Back then the system of price supports that has encouraged Japanese farmers today to convert practically every square foot of their land to rice cultivation did not exist. There was more food available in rural areas than is generally understood as wheat was widely grown, and large vegetable gardens were a standard feature of a family’s land. 21 Food reserves existed that were largely unaccounted for immediately after the war because responsibility for the storage and distribution of strategic stocks had been moved from national to principally prefectoral control in April due to the anticipated destruction of the transportation system (see chapter 7), and farmers had begun to hoard their crops in contravention of government directives.

The idea that the Japanese were about to run out of food any time soon was largely derived from exaggerated interpretations of the “Summary Report,” to the 104 reports in the United States Strategic Bombing Survey for the Pacific war, and the well-documented fear among some Japanese leaders that shortages could lead to severe unrest. 22 The idea that the Japanese were on the brink of starvation is usually (and rather loosely) attributed to the USSBS and the official Army Air Force history. However, using survey findings, what editors James Lea Cate and James C. Olson did in the multivolume history The Army Air Forces in World War II, was to detail the successful U.S. mine-laying efforts against Japanese shipping, which essentially cut Japanese oil and food imports, and they stated only that by mid-August “the calorie count of the average man’s fare had shrunk dangerously.” 23

Obviously some historians enthusiasm for the point they are trying to make has gotten the better of them since the reduced nutritional value of meals is somewhat different than imminent starvation. But the life-and-death question for a family that might well find itself in one of the areas of “localized famine” within as few as six months was how would the militarists in charge of their prefecture or district, who essentially believed that the population was expendable, allot the dwindling food supplies in the midst of an invasion? One indication of what likely would have transpired came from future prime minister Yoshida Shigeru, who before war-surplus food stocks from across the Pacific were rushed to Japan stated in January 1946 that as many as 10 million might die of starvation and malnutrition in “spot famines” that were forecast to begin by the summer of that year. 

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10 Million sucks, of course, but that's not collapse and is proportionally basically what the Soviets endurred.

   EwellHolmes ,

   So your saying Japan already had ~900,000 men practically on the beaches? That sounds a serious logistical problem.  It also means its going to be a very target rich environment for the covering bombardment.

One third of the defending force was slated for immediate defense on the beaches, with the remainder slated for interior defensive lines stretching across Kyushu. The Japanese by August of 1945 had already stockpiled six months worth of food, ammunition and chemical warfare supplies sufficient to fight the decisive battle in the region and were continuing apace in this regard, so they at the time and Post-War analysis by the American occupational authority rated them as sufficient for at least the six months timeframe logistically speaking.

As for the Kamikazes, we don't have to speculate they would be better than previous kamikazes because we know for an indisputable fact they were. IGHQ, as already stated, was throwing in their last reserves that they had withheld for this exact purpose. The IJAAF having 2,000 pilots with at least 70 hours of flying time while the IJN had 4,200 on hand who were considered sufficiently trained for night or low light missions; given the type of challenges those conditions presented, that means they were well trained. I think it should be also a basic matter of math here, even if they were of the same training as the previous cohorts. Let's do the math, shall we?

At Okinawa, the Japanese achieved a 6:1 ratio of expenditure in aircraft in terms of achieving a successful hit. For Kyushu defense, the Japanese formulated KETSU-GO with the plan calling for 9,000 aircraft to be brought to bare against the invasion fleet, with 6,255 to be used as Kamikazes. Let's round this down to 6,000 for ease.

6,000/6 = 1,000 successful hits.

Just to put that into perspective, there was 1,000 transports in total within the invasion fleet. Take in note, this is also assuming the Japanese only achieve the rate they did at Okinawa despite several new advantages. 

Finally, with regards to starvation, 10 million in the abstract is a lot and a humanitarian disaster, sure. It's also about the same thing the USSR and China endured during the war, so I have no doubt Japan can survive it.