How well prepared were the Japanese for Operation Downfall?

How well prepared were the Japanese for Operation Downfall?


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Whilst MacArthur was completely blind to reality in favour of his personal delusions of striding onto a volcanic beach with his pipe, there was enough intelligence to show that Olympic/Majestic was becoming increasingly unpalatable. The number of kamikazes ready to fly was simply staggering at over twelve thousand, the Japanese had hoped that they could destroy as much as 75% of the troopships before they hit the beaches in this fashion. Whilst this was likely an exaggeration, studies after the war concluded that as much as 25% of the troopships would be destroyed off the coast, and possibly even more than that.

The IJA at least matched the Americans in regular troops, with the USN estimating that they would outnumber them by the time Olympic/Majestic was likely to take place. This was without the certainty that the Japanese knew where the Americans were going to land, which they did, but it wasn't too difficult to conclude that potential landing zones were few and far between and thus rather obvious. It's almost certain that without the atomic bombs and the Soviet entry into the war that the plan would have been abandoned.

Coronet on it's own seems far more risky without hindsight, the Japanese forces on Kanto were incredibly menacing on paper purely by US estimations. The First General Army could have actually relied on many more troops than the Americans presumed, and whilst they couldn't launch an all out armoured counter-attack without any fuel, I imagine the feasibility of bypassing Kyushu would still have been being debated by the time that famine began to noticeably take hold in the spring of 1946.
 
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Whilst MacArthur was completely blind to reality in favour of his personal delusions of striding onto a volcanic beach with his pipe, there was enough intelligence to show that Olympic/Majestic was becoming increasingly unpalatable. The number of kamikazes ready to fly was simply staggering at over twelve thousand, the Japanese had hoped that they could destroy as much as 75% of the troopships before they hit the beaches in this fashion. Whilst this was likely an exaggeration, studies after the war concluded that as much as 25% of the troopships would be destroyed off the coast, and possibly even more than that.

According to Giangreco, Japanese estimations of success for the air campaign were roughly 20 percent of the invasion fleet destroyed before disembarkation; for its part the USN hung its hat on 10% losses. Either way this implies the equivalent of between 1.4 and 2.8 division-equivalents being totally lost at sea along with a myriad combat and support vessels accompanying the troop transports. Particularly devastating would have been the loss of one of the mobile bloodbanks off the coast: there were only a few of these scheduled to take part in Olympic and seeing one sunk would have spelled doom for countless critically wounded men ashore.

Bypassing Kyushu for a direct thrust at Tokyo would have been suicidal. While the Japanese defenses there wouldn't have been as well-prepared in late 1945 as they would be by mid-1946, Kanto was equal to (or just behind) Kyushu in terms of strategic priority and there were roughly twice as many IJA units there as in Yokoyama's 16th Area Army. Chief among these were the 36th Corps and the Kido Dageki Butai, a large mobile reserve essentially amounting to a 'Panzer Army.' With no air support from Kyushu the attackers would have been up against fearful odds had they attempted such a thing.
 

CalBear

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According to Giangreco, Japanese estimations of success for the air campaign were roughly 20 percent of the invasion fleet destroyed before disembarkation; for its part the USN hung its hat on 10% losses. Either way this implies the equivalent of between 1.4 and 2.8 division-equivalents being totally lost at sea along with a myriad combat and support vessels accompanying the troop transports. Particularly devastating would have been the loss of one of the mobile bloodbanks off the coast: there were only a few of these scheduled to take part in Olympic and seeing one sunk would have spelled doom for countless critically wounded men ashore.

Bypassing Kyushu for a direct thrust at Tokyo would have been suicidal. While the Japanese defenses there wouldn't have been as well-prepared in late 1945 as they would be by mid-1946, Kanto was equal to (or just behind) Kyushu in terms of strategic priority and there were roughly twice as many IJA units there as in Yokoyama's 16th Area Army. Chief among these were the 36th Corps and the Kido Dageki Butai, a large mobile reserve essentially amounting to a 'Panzer Army.' With no air support from Kyushu the attackers would have been up against fearful odds had they attempted such a thing.
The one major advantage that a direct thrust on Honshu provided was a massive reduction of the kamikaze threat. It is actually considerably farther from Northern Kyushu to Tokyo Bay than is is from South Kyushu to Okinawa. Most of the aircraft the Japanese had moved into position lacked the range to make the flight without refueling, many of the others could make it, but just barely, reducing the amount of burning fuel a successful strike would spread. The long flight would also provide additional time for interception, both by carrier aircraft and by USAAF assets on Okinawa. Even movement at night would be difficult, the kamikaze pilots were not sufficiently well trained to make night landings in combat conditions (minimal runway lighting, lack of landmarks, etc.) while the U.S. (and potentially RAF/RAAF) nightfighters off the carriers as well as from Okinawa would have easy hunting. I have also seen (granted in works supporting a direct strike) estimates that indicate the Japanese lacked the fuel to move the aircraft and still have sufficient gas to allow for actual strikes.

Whether the advantage of reduced kamikaze danger and isolating 900K Japanese troops on Kyushu would compensate for the loss of land based TacAir is a difficult one to answer.
 
The one major advantage that a direct thrust on Honshu provided was a massive reduction of the kamikaze threat. It is actually considerably farther from Northern Kyushu to Tokyo Bay than is is from South Kyushu to Okinawa. Most of the aircraft the Japanese had moved into position lacked the range to make the flight without refueling, many of the others could make it, but just barely, reducing the amount of burning fuel a successful strike would spread. The long flight would also provide additional time for interception, both by carrier aircraft and by USAAF assets on Okinawa. Even movement at night would be difficult, the kamikaze pilots were not sufficiently well trained to make night landings in combat conditions (minimal runway lighting, lack of landmarks, etc.) while the U.S. (and potentially RAF/RAAF) nightfighters off the carriers as well as from Okinawa would have easy hunting. I have also seen (granted in works supporting a direct strike) estimates that indicate the Japanese lacked the fuel to move the aircraft and still have sufficient gas to allow for actual strikes.

Whether the advantage of reduced kamikaze danger and isolating 900K Japanese troops on Kyushu would compensate for the loss of land based TacAir is a difficult one to answer.

According to the SCAP Final Report on Japanese demobilization, out of the 12,684 aircraft stationed in the Home Islands as of the termination of hostilities, 8,962 were on Honshu. Of the remainder, 2,637 were on Kyushu, 631 on Shikoku, and 454 on Hokkaido.

Here is a map showing the disposition of all airfields in Japan sans Hokkaido...

1556xco.jpg


... and kamikaze airfields in particular.

2ludzkz.jpg


Judging from this, while it looks like the majority of facilities specifically intended for suicide attacks were indeed situated in the south, the balance of overall aerial strength suggests that a strong response could have been mounted from more or less anywhere. And with all fighter cover in an ad hoc attack on Kanto coming solely from carrier-based air... ruh roh.
 
As more personal look at the people headed for Dropfall. Part of that increase of draftees was my father and an uncle of mine, they both knew where they were headed and that they would be in the infantry. Another uncle of mine was in the marines he had been in several invasions and he had written letters home about what it was like so neither had any illusions as to what they face. A little note the uncle who was in the Marines when the fighting ended was one of only three survivors in the platoon he served in. His platoon laid wire for telephones, so they were not supposed to be directly in combat. Just imagine what a infantry platoon would be like. My father passed his physical the day Nagasaki was bombed. You cannot imagine just how happy the two of them were when the Japanese surrendered. You could never tell him that the A bomb did not save his life. Just try to imagine being in his shoes.
 

Wendigo

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I wonder how many out of the 28 million Japanese in the Volunteer Fighting Corps would actually fight on their own volition not because the Kempeitai forced them to.
 
I don't know if they would have gone that far, it would have been a PR disaster of biblical proportions. There'd have been riots in the streets.

Another potential alternative not yet considered would perhaps have been an increased British/Commonwealth commitment besides the 3-5 divisions of the "Commonwealth Corps" already envisioned. This would circumvent the need to expand the draft at the price of significant modifications to the original plan and a greater UK role in the future of postwar Japan.

Oh, but they did. See below from Wikipedia on the "Advanced Service Rating Score" otherwise known as points:

An enlisted man needed a score of 85pts to be considered for the demobilization. The scores were determined as follows for each:

  1. Month in service = 1 pt
  2. Month in service overseas = 1 pt
  3. Combat award (including medal and battle stars) = 5 pts
  4. Dependent child under 18 = 12 pts
Time of service was calculated from September 16, 1940. The four criteria were the only ones from which points were calculated. No points were issued for age, marriage or dependents over the age of 18. Battles and awards were also only accepted from a predetermined list.

Item number 3 was the real point of contention. I don't have a reference, but the definition of "battle stars" was complex and somewhat branch related, awarding various point schemes for "combat experience" while overseas.

So, imagine you enter the AAF in June 1943, arrive in the UK in March 1944. Fly two missions in April 1944 and during the second mission you are wounded, shot down and captured; and assigned to Stalag Luft IV at Gross Tychow, Pomerania. In February 1945 you begin "The Black March", walking, freezing, starving and sleeping in fields until liberated (500 mi West) by 21 Army Group on May 2, 1944. You are told to "head West" with your new prisoners (former guards) and two days later arrive at a divisional camp where you are "deloused", fed and told to find your way South toward the Americans.

You return to the US in June 1945 (many ex POW were sent back quickly since it was easier than figuring out what to do with them within the theater). That's definitely a good deal, right? After a 30-day leave, you report to your assigned air base (assuming you will be discharged) only to discover you have a grand total of 40 points (25 for time in service, purple heart = 5, two missions = 10). Now you are shocked, after the point system has determined that you have not yet "done your part". Next you find out that since you have combat experience you are much more valuable than the newly trained air crew; and finally you investigate this "point system" and discover that the hell you experienced as a POW counts exactly the same as stateside service. Before you know it, you are on your way to SFO by train and Tinian by ship to join your new B-29 squadron. Talk about pissed off! But you soldier on, in part because you are told that refusing to go could result in a charge of "mutiny".

Good news is that they dropped the bomb while you are en-route. Now you are a happy guy, blessing President Truman for dropping the bomb. You are off-loaded in Guam and the ship starts loading personnel from Tinian to head home. "Why not me you ask?" only to be told that you are a brand new replacement and veterans get to go home first. Are you pissed again? Yes, write your congressmen...
 
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CalBear

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According to the SCAP Final Report on Japanese demobilization, out of the 12,684 aircraft stationed in the Home Islands as of the termination of hostilities, 8,962 were on Honshu. Of the remainder, 2,637 were on Kyushu, 631 on Shikoku, and 454 on Hokkaido.

Here is a map showing the disposition of all airfields in Japan sans Hokkaido...

1556xco.jpg


... and kamikaze airfields in particular.

2ludzkz.jpg


Judging from this, while it looks like the majority of facilities specifically intended for suicide attacks were indeed situated in the south, the balance of overall aerial strength suggests that a strong response could have been mounted from more or less anywhere. And with all fighter cover in an ad hoc attack on Kanto coming solely from carrier-based air... ruh roh.
As is often the case, particularly for something like Olympic, the information is correct, but it is still wrong.

This was deployment in early August, not November. The Japanese more or less knew when and where (it was more or less a math and planning equation, didn't need a lot of intel gathering to figure out how long it would take to build up forces on Luzon and Okinawa, what beaches were suitable for landing, when the Moon and tides would be right). They also knew they would be lots of effort to shape the battlefield. Keep the aircraft scattered until the day get s closer (several thousand of them were, according to some sources, still disassembled to make movement easier, and their locations less obvious).
 
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CalBear

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I wonder how many out of the 28 million Japanese in the Volunteer Fighting Corps would actually fight on their own volition not because the Kempeitai forced them to.
How many members of the Red Army or of the Soviet partisans were only fought because of Stalin and the NKVD?

Doesn't really matter how happy they were doing it. Just have to do it.
 
Judging from this, while it looks like the majority of facilities specifically intended for suicide attacks were indeed situated in the south, the balance of overall aerial strength suggests that a strong response could have been mounted from more or less anywhere. And with all fighter cover in an ad hoc attack on Kanto coming solely from carrier-based air... ruh roh.

On the bright side, the US Navy just might have the Grumman F8F Bearcat in numbers by this time.
 
While the military operation and the possible casualties has always been discussed intensely, I'm particularly curious about the effect of such a bloody war on the Japanese society. Will Japan survive as a nation after this war? If so, how this war affect the nation as a whole, the economical, sociological and psychological aspect of the Japanese people?

Definitely it will have a staggering effect, but could anyone make up the detail possibilities?
 
Oh, but they did. See below from Wikipedia on the "Advanced Service Rating Score" otherwise known as points:

An enlisted man needed a score of 85pts to be considered for the demobilization. The scores were determined as follows for each:

  1. Month in service = 1 pt
  2. Month in service overseas = 1 pt
  3. Combat award (including medal and battle stars) = 5 pts
  4. Dependent child under 18 = 12 pts
Time of service was calculated from September 16, 1940. The four criteria were the only ones from which points were calculated. No points were issued for age, marriage or dependents over the age of 18. Battles and awards were also only accepted from a predetermined list.

However, "essential" personnel would be retained regardless of the above. My uncle enlisted in 1942 and fought in North Africa, Italy and D-Day. I used the above formula which indicated he wouldn't be called up but, as he was considered a specialist, that probably wouldn't have mattered. He told me he'd done his hitch, and now it was somebody else's turn. Getting him into the Pacific would NOT have been easy...
 
As is often the case, particularly for something like Olympic, the information is correct, but it is still wrong.

This was deployment in early August, not November. The Japanese more or less knew when and where (it was more or less a math and planning equation, didn't need a lot of intel gathering to figure out how long it would take to build up forces on Luzon and Okinawa, what beaches were suitable for landing, when the Moon and tides would be right). They also knew they would be lots of effort to shape the battlefield. Keep the aircraft scattered until the day get s closer (several thousand of them were, according to some sources, still disassembled to make movement easier, and their locations less obvious).

Though I'm not quite sure they intended to expend their entire air strength in the battle for Kyushu alone. JM-85 pgs. 19 and 20 lists the projected commitment there as 6,225 kamikazes with 2,000 fighters for air superiority plus a supporting attack by 330 of the IJN's best remaining elite pilots against the US carriers to prevent them from coming to the aid of the transports. The final actions would have been a 150 plane night attack on the US escort ships and the dropping of a 1,200 man raiding force from 100 transports in a suicide run against Okinawa for the purpose of disrupting its airfields prior to the landings. That adds up to just over 8,800 aircraft, or around 4,000 short of the total on hand in August, let alone new production available by November.

Therefore, even under the Ketsu-Go OPLAN there still would have been thousands of aircraft to spare with which to mount an attack, including and especially in the defense of Tokyo.
 
There will be a staggering depopulation of Japan, exactly how bad will depend on how long the fighting goes on. Not only will large numbers of young men who would live OTL die, there will be massive civilian casualties. Even under the best circumstances the disease and starvation amongst civilians will decimate the very young and very old and many surviving children will be stunted physically and mentally due to malnutrition. The loss due to disease and starvation will extend well beyond the end of fighting as importation of adequate food for the local population will be difficult, the transportation net even more limited than OTL with priority going to the needs of US forces, and even more of the housing stock down to small towns and villages being destroyed exposing survivors to the elements. The resources needed to deal with large numbers of Allied wounded in theater and back in their home countries, will mean less aid possible for the Japanese.

The loss of so many young men, over and above OTL, and the beggary of the majority of the population will mean a marked increase in Japanese women trading sex for food, and large numbers of "half-Japanese". Given the emphasis on racial purity in Japanese society these children will represent a major cultural challenge. Note OTL the Japanese government had designated those women to service the needs of occupiers to prevent this sort of thing. Another effect of this massive depopulation will be a continuing labor shortage as the economy recovers, and of necessity women entering in to the labor force in a much larger number.

Perhaps the major effect longer term will be a desire of the US to remake Japanese society on a much broader basis. Lots of Japanese traditions, industrial combines, etc that were allowed to continue OTL will be suppressed. I would not be surprised to see the Yasukuni Shrine suffer the same fate the swatika over the stadium in Munich suffered - destroyed by Army Engineers as a matter of course. Overall I would expect the Japan of 2016 to have a smaller population that OTL, with a much larger leavening of non-Japanese DNA, economically Japan will be less of a powerhouse, and many traditional aspects of Japanese culture will exist only in history books.
 
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