WI: Operation Downfall happens?

[GDIS Pathe]

3. The three first atomic bombs were successful prototypes, but due to cost mass production was not set up until after the Soviet test of a nuclear device in 1949. Add to that factor the uncertainty of their initial success, and it is understandable that a fourth bomb was not available until January 1946 and at a slow rate thereafter. As late as June 1950, the U.S. arsenal had only 100 nuclear weapons. Without a Japanese surrender, it is likely that industrial preparation for mass production would be set in motion in September 1945, but until that took effect, weapons would be used one at a time as they were completed. It’s tough to calculate the effects of the acceptability of nuclear bombs as just another tactical weapon on the postwar world.

A-Bomb production was massively curtailed as a result of the end of the war, Groves sent a memo to the US Chief of Staff in July about A-Bomb production. Relevant Section

The final components of the first gun type bomb have arrived at Tinian, those of the first implosion type should leave San Francisco by airplane early on 30 July. I see no reason to change our previous readiness predictions on the first three bombs. In September, we should have three or four bombs. One of these will be made from 235 material and will have a smaller effectiveness, about two-thirds that of the test type, but by November, we should be able to bring this up to full power. There should be either four or three bombs in October, one of the lesser size. In November, there should be at least five bombs and the rate will rise to seven in December and increase decidedly in early 1946. By some time in November, we should have the effectiveness of the 235 implosion type bomb equal to that of the tested plutonium implosion type.

Atomic Bomb: Decision -- Bomb Production Schedule, July 30, 1945

The Manhattan Project could make atomic bombs at an ever-increasing rate

www.dannen.com

 

[Eric C Johnson]

My compliments. MG Leslie Groves is a highly credible source. His estimate of production annotated above serves to significantly reinforce my point. What is the effect both on the final stages of the war against Japan, and in the postwar world in general, of a considerable reduction in the threshold for using nuclear weapons?

 

[History Learner]

The question I always have on the KETSU-GO kamikaze numbers was not so much the planes but where were the pilots going to come from (unless they were going to use up all the 2,000 and 4,200 mentioned above).

I'm also not sure that it would be 10:1 for the air forces in downfall?

(OOB for Downfall)

United States Naval and Air Forces

• Third Fleet (Adm. William F. Halsey):
  • 20 CV and CVL;
  • 9 BB;
  • 26 CB, CA, CL, CLAA;
  • 75 DD
• Fifth Fleet (Adm. Raymond A. Spruance):
  • 36 CVE;
  • 11 BB;
  • 26 CA and CL;
  • 387 DD and DE;
  • 394 AKA, AP, APA, APD, APH;
  • 977 LSD, LSM, LST, and LSV
• Seventh Fleet (Adm. Thomas C. Kinkaid):
• Far East Air Forces (Gen. George C. Kenney) (119,000 men): - 14 bomber groups, 10 fighter groups
  • Fifth Air Force
  • Seventh Air Force
  • Thirteenth Air Force
• United States Strategic Air Forces in the Pacific (Gen. Carl A. Spaatz, Maj. Gen. Curtis LeMay)
  • Twentieth Air Force (Lt. Gen. Nathan Twining) (77,000 men)
    • 1,000 B-29 Superfortresses
  • Eighth Air Force (Lt. Gen. Jimmy Doolittle)

There's also the problem that Japan know Kyushu is not going to be the only Allied landed in a home island invasion so it unlikely they spend all their kamikazes on downfall. Also even of they do decide to expend them all on downfall are they going to base all of them on Kyushu or are some going to have come in from Honshu?

(similarly there were dummy attacks planned to lure them out as well).

There;s also the point that the air force will be running campaigns against the Japanese airfields in the run up to all this, so assuming that there will 6000 kamikazes ready to go or be deployable when it's time is a bit of an assumption.

I;m also not sure about that 6:1 kamakazes to ship sinking. figure either

simply because not every hit ended up in a ship sinking!

The exact number of ships sunk is a matter of debate. According to a wartime Japanese propaganda announcement, the missions sank 81 ships and damaged 195, and according to a Japanese tally, kamikaze attacks accounted for up to 80% of the U.S. losses in the final phase of the war in the Pacific. In a 2004 book, World War II, the historians Wilmott, Cross and Messenger stated that more than 70 U.S. vessels were "sunk or damaged beyond repair" by kamikazes.
According to a U.S. Air Force webpage:
Australian journalists Denis and Peggy Warner, in a 1982 book with Japanese naval historian Sadao Seno (The Sacred Warriors: Japan's Suicide Legions), arrived at a total of 57 ships sunk by kamikazes. Bill Gordon, an American Japanologist who specialises in kamikazes, lists in a 2007 article 47 ships known to have been sunk by kamikaze aircraft. Gordon says that the Warners and Seno included ten ships that did not sink. He lists:

• three escort carriers: USS St. Lo, USS Ommaney Bay, and USS Bismarck Sea
• 14 destroyers, including the last ship to be sunk, USS Callaghan (DD-792) on 29 July 1945, off Okinawa
• three high-speed transport ships
• five Landing Ship, Tank
• four Landing Ship Medium
• three Landing Ship Medium (Rocket)
• one auxiliary tanker
• three Victory ships
• three Liberty ships
• two high-speed minesweepers
• one Auk class minesweeper
• one submarine chaser
• two PT boats
• two Landing Craft Support

That's with either 2800 or just under 4,000 Kamikaze attackers, but a few points

1). even if not sunk, damaged can still inflict causalities on an invasion force.

2). the above is for all kamikaze attacks throughout the, only anti Kamikaze tactics improved

3). conversely to 2 above the quality of IJN and IJAAF pilots was decreasing, and the worse your pilots the worse your kamikazes.


Ultimately kamikaze never really proved strategically decisive so, any plan that's based on well this time they will be, I'm not sure about

@BobTheBarbarian did the research on this and stated the case far more eloquently than I ever could in this thread:

Sorry for long delay. Real life frequently finds a means of getting in the way...​

​

To recap for those who are just reading this post, the long and short of it is this: if the Second World War continued past August 1945 and the United States pressed on with its planned attack on the Japanese mainland, the probability that the first stage invasion, Operation Olympic, would have resulted in a military catastrophe was very high.​

​

The main reasons for this were twofold: firstly, US planners were consistently "behind the times" in terms of their assessments of Japanese strength assigned to the defense of Kyushu. This was the case right up until the end of the war - only by the middle of August did the picture become more clear, and even then, in D.M. Giangreco's words, it was still a "serious underestimate." Conversely - and this is seldom emphasized - Japanese planners overestimated the strength and capabilities of the Allied forces, such that there was a two-way intelligence gap. This cannot be repeated enough: Japanese military intelligence correctly predicted not only the timing and sequence of Allied operations, but also the approximate strength assigned to each. When they erred, they tended to be on the side of caution, anticipating greater forces than would be brought to bear against them and on an accelerated timetable. In plain language, the Japanese had "figured us out" and deprived the Allies of operational surprise, calibrating their defensive effort to repel an invasion much stronger than the one we actually planned.[1]​

​

Given this, the forces and means the Americans and their allies assigned to Olympic were totally inadequate to assure victory, particularly air and ground forces. These facts can be readily discerned through superimposing the respective operational plans, OLYMPIC for the Americans and MUTSU-GO for the Japanese, on top of each other.​

​

As we know from the failed raid on Dieppe, control of the air is co-equal with control of the sea for ensuring the success of a landing. Air supremacy, moreover, also frees up the naval forces to do their job against potential surface or undersea threats without worrying about enemy air attacks. I state the obvious here, because at Kyushu the Allies would NOT have possessed air supremacy. Excluding roughly 2,000 heavy bombers assigned to strategic duties, tactical air support for Olympic was to amount to 1,850 land based planes of General Kenney's FEAF based in the Ryukyus (excluding the 2nd Marine Air Wing) and 3,000 single engine planes aboard flat tops of the Third and Fifth Fleets, the latter of which included the British Pacific Fleet [2]. In other words, about 5,000 aircraft in total.​

​

Against this, on the Japanese side, out of 12,684 aircraft of all types in the country as of August 1945, the "Ketsu" Operational plan called for at least 9,000 to be brought into the Kyushu battle as follows:[3]​

​

- 140 for air reconnaissance to detect the approach of the Allied fleet​

- 6,225 kamikazes and conventional bombers to target the assault shipping​

- 2,000 "air superiority" fighters to occupy the opposing CAP​

- 330 conventional bombers flown by elite pilots to attack the carrier task group​

- 150 further conventional bombers flown by elite pilots for a night attack on the US escort ships​

- 100 paratroops carriers inserting approximately 1,200 commandos at US airfields on Okinawa, inspired by the relative success of a small-scale sortie months earlier​

​

The duration of all this was expected to be just 10 days. As can be seen, the Japanese would have possessed a numerical advantage of roughly 2 : 1 overall in tactical aircraft. Furthermore, if we consider that realistically only allied fighters matter in this comparison (bombers don't do CAP), then in fact the actual ratio would be about 4 : 1. Against such odds, American combat air patrol would be incapable of stopping the deluge of attacking planes, and the fleet would suffer enormous damage as a consequence.​

​

IGHQ devised this plan based on an inventory of 8,500 serviceable aircraft in July 1945, to which it was hoped an additional 2,000 could be added by the time of the invasion.[4] Reserves of aviation fuel, though exceedingly scarce, were adequate to carry out the above plan: the strategic stockpile set apart for the decisive battle amounted to 190,000 barrels for the Army and 126,000 barrels for the Navy. By July 1945 the total inventory of aviation fuel in the Japanese mainland comprised 1,156,000 barrels. As a means of visualizing this in action, the entire three month period from April to June 1945 burned 604,000 barrels within Japan's inner zone, including the "Kikusui" operations at Okinawa. Despite this, consumption of fuel actually decreased 132,000 barrels from the previous quarter and 201,000 barrels from the one before that, owing to shortening distances. At Kyushu, the battlefield would be Japan itself, flight times would be short, and patterns of approach highly variable. As was the case in the Philippines, the mountainous coastline would protect attacking aircraft from being discovered on radar until they were very close to the invasion fleet.[5]​

​

From the experience at Okinawa, the loss or expenditure of 1,430 bombers and kamikaze aircraft by the Japanese Army and Navy caused about 10,000 casualties, half of them deaths, to American and British forces, or about 7 casualties per Japanese aircraft committed. If, based on the above factors, the Japanese improved their performance at Kyushu, it could be expected that losses at sea could tally up to many tens of thousands, effectively crippling the US Sixth Army before it even got ashore. This alone would be enough to put the invasion in jeopardy, and it doesn't even take into account operations by remaining IJN fleet elements such as submarines, destroyers, or fast attack craft. Unfortunately, the situation that would have greeted the Sixth Army on the ground was nearly as bad.​

​

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.[12] 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.​

​

In other words, to restate Major Arens' conclusion earlier in this thread:​

​

"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."​

​

I emphasize again, there is no credible scholarship anywhere in the world who can seriously claim that an invasion of mainland Japan would have been anything short of a catastrophe; a savage climax to the most horrible of all man's wars. It would not have been easy, far from it, and its ramifications would have undoubtedly lent themselves to the creation of a world radically different from the one we see today.​

​

Some tables ---​

​

​

Table 1: Japanese estimate of Allied air strength and the planned reality, July 1945[6]​

​

Jap Estimate . . . . . . . . . . . . . . . . . Allied Plan​

Land Based . . . . . 6,000* . . . . . . . . . . . . . . . . . . . 2,000​

Carrier " . . 3,300-3,800* . . . . . . . . . . . . . . . . . . . 3,000​

​

* Estimate for land-based craft: 1,500 B-29, 1,400 other heavy bombers, 1,100 medium bombers, 2,000 fighters​

* Estimate for carrier-based craft: 2,600 to 3,100 USN and 700 RN​

​

Table 2: Japanese estimate of Allied invasion fleet and planned reality, July 1945[7][8]​

​

​

Jap Estimate . . . . . . . . . . . . . . . . . Allied Plan​

​

USN​

Carriers (all types). . 50 . . . . . . . . . . . . . . . . . . . . . . .58​

Battleships . . . . . . . 21 . . . . . . . . . . . . . . . . . . . . . . .20​

Cruisers . . . . . . . . . 54 . . . . . . . . . . . . . . . . . . . . . . .52​

DDs and DEs . . . . . 330 . . . . . . . . . . . . . . . . . . . . . .442​

​

RN​

Carriers (all types). . 13 . . . . . . . . . . . . . . . . . . . . . . .12​

Battleships . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . n/a​

Cruisers . . . . . . . . . . 8 . . . . . . . . . . . . . . . . . . . . . . n/a​

DDs and DEs . . . . . . 40. . . . . . . . . . . . . . . . . . . . . . n/a​

​

Table 3: Japanese estimate of Allied ground forces and planned reality, July 1945[9][10]​

​

​

Jap Estimate . . . . . . . . . . . . . . . . . Allied Plan​

​

​

Kyushu . . . . . . . 15-40 . . . . . . . . . . . . . . . . . . . . . . .14​

Honshu . . . . . . . 30-50 . . . . . . . . . . . . . . . . . . . . 38-40​

​

Figure: Japanese dispositions and counterattack plan for Ariake Bay, 57th Army​

​

​

Spoiler

​

​

​

[1] - Giangreco p. xx​

[2] - Allen and Polmar p. 299, Skates p. 170, Sutherland p.9​

[3] - JM-85 pp. 19-21​

[4] - Reports of Gen. MacArthur vol. 2. ch.2 note 100​

[5] - Giangreco p. 80​

[6] - Reports of Gen. MacArthur vol. 2 part.2 ch.19 p. 639, notes 101 and 102​

[7] - same as above​

[8] - Sutherland p.9​

[9] - Giangreco p. 82, Homeland Operations Record p. 75, 82​

[10] - Reports of Gen. MacArthur, JM-85​

[11] - "Olympic vs Ketsu-Go" Marine Corps Gazette 1965​

[12] - Drea "In service of the Emperor" p. 148​

 

[Rickshaw]

7. An invasion of Japan would remain an overwhelming American enterprise. As an aside, the X Commonwealth Corps under LTG Charles Kneightley was allocated 3 British, 6 Canadian and 10 Australian Divisions. I believe 4 NZ Armoured and 9 New Zealand Infantry Brigades were allocated as well, but cannot confirm. 9 New Zealand Infantry Brigade did arrive in Japan as occupation troops in February 1946. X Commonwealth Corps was allocated to Operation Coronet, the invasion of Honshu in March 1946, initially as a reserve afloat pending success or failure of initial landings. Two additional divisions, never identified by planners, were to reinforce X Commonwealth Corps about 40 days later.

That sized Australian force would require significant shipping to move it from Australia to Japan. I don't doubt it would be possible but it would be a significant burden on the Allies part. Then you have the problem of logistics for such a force. They all used a different calibre small arms compared to the American forces, as well as artillery and AFVs. Providing the required amount of back up, once they had landed and were engaged in combat would be again, a significant burden. Australia tended to pay it's own logistic costs, however it lacked the transport to supply such a force let alone move it. BCOF (British Commonwealth Occupation Forces) proved too expensive for the British, let alone the Australians. Which is why they were being wound down at the outbreak of the Korean War.

 

[TDM]

@BobTheBarbarian did the research on this and stated the case far more eloquently than I ever could in this thread:

Sorry for long delay. Real life frequently finds a means of getting in the way...​

​

​

​

No worries​

​

To recap for those who are just reading this post, the long and short of it is this: if the Second World War continued past August 1945 and the United States pressed on with its planned attack on the Japanese mainland, the probability that the first stage invasion, Operation Olympic, would have resulted in a military catastrophe was very high.

​

The main reasons for this were twofold: firstly, US planners were consistently "behind the times" in terms of their assessments of Japanese strength assigned to the defense of Kyushu. This was the case right up until the end of the war - only by the middle of August did the picture become more clear, and even then, in D.M. Giangreco's words, it was still a "serious underestimate." Conversely - and this is seldom emphasized - Japanese planners overestimated the strength and capabilities of the Allied forces, such that there was a two-way intelligence gap. This cannot be repeated enough: Japanese military intelligence correctly predicted not only the timing and sequence of Allied operations, but also the approximate strength assigned to each. When they erred, they tended to be on the side of caution, anticipating greater forces than would be brought to bear against them and on an accelerated timetable. In plain language, the Japanese had "figured us out" and deprived the Allies of operational surprise, calibrating their defensive effort to repel an invasion much stronger than the one we actually planned.[1]​

​

Given this, the forces and means the Americans and their allies assigned to Olympic were totally inadequate to assure victory, particularly air and ground forces. These facts can be readily discerned through superimposing the respective operational plans, OLYMPIC for the Americans and MUTSU-GO for the Japanese, on top of each other.​

​

As we know from the failed raid on Dieppe, control of the air is co-equal with control of the sea for ensuring the success of a landing. Air supremacy, moreover, also frees up the naval forces to do their job against potential surface or undersea threats without worrying about enemy air attacks. I state the obvious here, because at Kyushu the Allies would NOT have possessed air supremacy. Excluding roughly 2,000 heavy bombers assigned to strategic duties, tactical air support for Olympic was to amount to 1,850 land based planes of General Kenney's FEAF based in the Ryukyus (excluding the 2nd Marine Air Wing) and 3,000 single engine planes aboard flat tops of the Third and Fifth Fleets, the latter of which included the British Pacific Fleet [2]. In other words, about 5,000 aircraft in total.​

​

Against this, on the Japanese side, out of 12,684 aircraft of all types in the country as of August 1945, the "Ketsu" Operational plan called for at least 9,000 to be brought into the Kyushu battle as follows:[3]​

​

- 140 for air reconnaissance to detect the approach of the Allied fleet​

- 6,225 kamikazes and conventional bombers to target the assault shipping​

- 2,000 "air superiority" fighters to occupy the opposing CAP​

- 330 conventional bombers flown by elite pilots to attack the carrier task group​

- 150 further conventional bombers flown by elite pilots for a night attack on the US escort ships​

- 100 paratroops carriers inserting approximately 1,200 commandos at US airfields on Okinawa, inspired by the relative success of a small-scale sortie months earlier​

​

The duration of all this was expected to be just 10 days. As can be seen, the Japanese would have possessed a numerical advantage of roughly 2 : 1 overall in tactical aircraft. Furthermore, if we consider that realistically only allied fighters matter in this comparison (bombers don't do CAP), then in fact the actual ratio would be about 4 : 1. Against such odds, American combat air patrol would be incapable of stopping the deluge of attacking planes, and the fleet would suffer enormous damage as a consequence.​

​

IGHQ devised this plan based on an inventory of 8,500 serviceable aircraft in July 1945, to which it was hoped an additional 2,000 could be added by the time of the invasion.[4] Reserves of aviation fuel, though exceedingly scarce, were adequate to carry out the above plan: the strategic stockpile set apart for the decisive battle amounted to 190,000 barrels for the Army and 126,000 barrels for the Navy. By July 1945 the total inventory of aviation fuel in the Japanese mainland comprised 1,156,000 barrels. As a means of visualizing this in action, the entire three month period from April to June 1945 burned 604,000 barrels within Japan's inner zone, including the "Kikusui" operations at Okinawa. Despite this, consumption of fuel actually decreased 132,000 barrels from the previous quarter and 201,000 barrels from the one before that, owing to shortening distances. At Kyushu, the battlefield would be Japan itself, flight times would be short, and patterns of approach highly variable. As was the case in the Philippines, the mountainous coastline would protect attacking aircraft from being discovered on radar until they were very close to the invasion fleet.[5]​

​

From the experience at Okinawa, the loss or expenditure of 1,430 bombers and kamikaze aircraft by the Japanese Army and Navy caused about 10,000 casualties, half of them deaths, to American and British forces, or about 7 casualties per Japanese aircraft committed. If, based on the above factors, the Japanese improved their performance at Kyushu, it could be expected that losses at sea could tally up to many tens of thousands, effectively crippling the US Sixth Army before it even got ashore. This alone would be enough to put the invasion in jeopardy, and it doesn't even take into account operations by remaining IJN fleet elements such as submarines, destroyers, or fast attack craft. Unfortunately, the situation that would have greeted the Sixth Army on the ground was nearly as bad.​

​

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.[12] 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.​

​

In other words, to restate Major Arens' conclusion earlier in this thread:​

​

"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."​

​

I emphasize again, there is no credible scholarship anywhere in the world who can seriously claim that an invasion of mainland Japan would have been anything short of a catastrophe; a savage climax to the most horrible of all man's wars. It would not have been easy, far from it, and its ramifications would have undoubtedly lent themselves to the creation of a world radically different from the one we see today.​

​

Some tables ---​

​

​

Table 1: Japanese estimate of Allied air strength and the planned reality, July 1945[6]​

​

Jap Estimate . . . . . . . . . . . . . . . . . Allied Plan​

Land Based . . . . . 6,000* . . . . . . . . . . . . . . . . . . . 2,000​

Carrier " . . 3,300-3,800* . . . . . . . . . . . . . . . . . . . 3,000​

​

* Estimate for land-based craft: 1,500 B-29, 1,400 other heavy bombers, 1,100 medium bombers, 2,000 fighters​

* Estimate for carrier-based craft: 2,600 to 3,100 USN and 700 RN​

​

Table 2: Japanese estimate of Allied invasion fleet and planned reality, July 1945[7][8]​

​

​

Jap Estimate . . . . . . . . . . . . . . . . . Allied Plan​

​

USN​

Carriers (all types). . 50 . . . . . . . . . . . . . . . . . . . . . . .58​

Battleships . . . . . . . 21 . . . . . . . . . . . . . . . . . . . . . . .20​

Cruisers . . . . . . . . . 54 . . . . . . . . . . . . . . . . . . . . . . .52​

DDs and DEs . . . . . 330 . . . . . . . . . . . . . . . . . . . . . .442​

​

RN​

Carriers (all types). . 13 . . . . . . . . . . . . . . . . . . . . . . .12​

Battleships . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . n/a​

Cruisers . . . . . . . . . . 8 . . . . . . . . . . . . . . . . . . . . . . n/a​

DDs and DEs . . . . . . 40. . . . . . . . . . . . . . . . . . . . . . n/a​

​

Table 3: Japanese estimate of Allied ground forces and planned reality, July 1945[9][10]​

​

​

Jap Estimate . . . . . . . . . . . . . . . . . Allied Plan​

​

​

Kyushu . . . . . . . 15-40 . . . . . . . . . . . . . . . . . . . . . . .14​

Honshu . . . . . . . 30-50 . . . . . . . . . . . . . . . . . . . . 38-40​

​

Figure: Japanese dispositions and counterattack plan for Ariake Bay, 57th Army​

​

​

Spoiler

​

​

​

[1] - Giangreco p. xx​

[2] - Allen and Polmar p. 299, Skates p. 170, Sutherland p.9​

[3] - JM-85 pp. 19-21​

[4] - Reports of Gen. MacArthur vol. 2. ch.2 note 100​

[5] - Giangreco p. 80​

[6] - Reports of Gen. MacArthur vol. 2 part.2 ch.19 p. 639, notes 101 and 102​

[7] - same as above​

[8] - Sutherland p.9​

[9] - Giangreco p. 82, Homeland Operations Record p. 75, 82​

[10] - Reports of Gen. MacArthur, JM-85​

[11] - "Olympic vs Ketsu-Go" Marine Corps Gazette 1965​

[12] - Drea "In service of the Emperor" p. 148​

To be honest that's all really just restating the initial argument it didn't answer the questions, and frankly changing the kamikaze stats from ships sunk per plane to causalities inflicted just begs more questions.

1). if the average during Okinawa was 7 casualties per plane (including bombers not just kamikazes and bombers were more effective that kamikazes), then even 6,000 kamikaze attacks really isn't going to have the effect described (plus there's still the issues where are the kamikaze pilots going to come from going by your last posted figures that's all available pilots, despite the fact that pilots are being assigned other duties. Plus are the Japanese really going to use up all their pilots on downfall knowing that's not the last Japanese beach that will landed on).

2)., The assertion that kamikaze attacks would suddenly become far more successful than they had been so far isn't supported. For instance hoping another 2,000 planes would become available form July 1945 on wards seems rather unlikely. Plus if there's not enough pilots it's irrelevant. It ignores the fact that there's going to be an ongoing air campaign against all these preparations. Not only will this campaign degrade these preparations but Japanese planes and more importantly pilots will be lost fighting it*. You still haven't supported why the big blue blanket won't work. The Japanese can't put 6,000 kamikaze planes on Kyushu a lot of these planes are going to be coming in from Honshu. And the US seem to have more than enough planes and ship cover in teh operation to counter it. These is I think a big issue in taking all possible planes in Japan (including the hoped for ones) in one total and all the planes the US have actually deployed and comparing them like that. It doesn't really work like that you have to look at deployable figures at any given time. There is a similar point about fuel reserves, the number of barrels the Japanese can scrape together in theory in July 1945, really isn't going to be the same amount actually available in airfields a few months later.


The last point the typhoon, that's going to effect defensive measures as well, and frankly a months delay is only going to worsen the Japanese position because it will be another month under a concerted air campaign but another month of preparations for the US who won't be. another point about US preparations, there seem to be lots of claims of the US were going to be surprised the US were ill-prepared etc., Only the US has by this point spent a few years planning and executing seaborne invasions, In N.Africa, Europe and the Pacific.

On the final point

"I emphasize again, there is no credible scholarship anywhere in the world who can seriously claim that an invasion of mainland Japan would have been anything short of a catastrophe; "

That a big claim because honestly most books I've read have said it was going to be bloody, but more due to winkling out entrenched committed defenders than kamikaze) and the us would have to heavily rely on air power to try and keep their one causalities down. But not to the point it couldn't be done. In general I think this does all boil down to the cardinal assertion that when the chips are down and men are dying the US can not withstand casualties like other countries do (The Japanese plans was certainly based on this). and frankly we saw that kind of thinking all throughout the war and it was never shown to be true. I guess it kind of depends on what you men by catastrophe, I mean yes anyone who thinks the US forces are going to land and taken Japan and have a nice time doing it is kidding themselves, and I can well believe it would be the campaign that would see the greatest US casualty numbers in the war




*this last brings up another point. Where where all these Japanese pilots and planes during the strategic bombing campaign? Well they started off trying to fight it but what happened:

Air combat was most intense in late 1944 and early 1945. Following the first B-29 raids on Tokyo, the number of IJN aircraft assigned to air defense duties was greatly increased and all 12-centimeter (4.7 in) guns were allocated to protect the capital.[206] Fighters stationed to defend Japan's main industrial areas frequently intercepted American air raids between 24 November 1944 and 25 February 1945, and inflicted significant losses for a period. The number of fighters available declined from late January, however.[207] Poor coordination between the IJAAF and IJN also continued to hamper Japan's defensive efforts throughout this period.[208] The Americans suffered few losses from Japanese fighters during the night raids which were conducted from March 1945 until the end of the war.[209]
Resistance to the air raids decreased sharply from April 1945. On 15 April the IJAAF and IJN air defense units were belatedly placed under a single command when the Air General Army was formed under the command of General Masakazu Kawabe, but by this time the fighter force's effectiveness had been greatly reduced due to high rates of casualties in training accidents and combat. Due to the poor standard of the remaining pilots and the deployment of P-51 Mustangs to escort B-29s, the Japanese leadership decided in April to withdraw their remaining fighters from combat. These aircraft were placed in reserve to counterattack the Allied invasion.[210] As a result, few of the subsequent Allied raids were intercepted.[210] The effectiveness of Japanese anti-aircraft batteries also decreased during 1945 as the collapse of the national economy led to severe shortages of ammunition.[210] Moreover, as the anti-aircraft guns were mainly stationed near major industrial areas, many of the raids on small cities were almost unopposed.[211] Imperial General Headquarters decided to resume attacks on Allied bombers from late June, but by this time there were too few fighters available for this change of tactics to have any effect.[212] The number of fighters assigned to the Air General Army peaked at just over 500 during June and July, but most frontline units had relatively few serviceable aircraft.[213] During the last weeks of the war Superfortresses were able to operate with near impunity owing to the weakness of the Japanese air defenses; LeMay later claimed that during this period "it was safer to fly a combat mission over Japan than it was to fly a B-29 training mission back in the United States".[214]
Overall, Japanese fighters shot down 74 B-29s, anti-aircraft guns accounted for a further 54, and 19 were downed by a combination of anti-aircraft guns and fighters. IJAAF and IJN losses during the defense of Japan were 1,450 aircraft in combat and another 2,750 to other causes.[215]


Leaving aside what the above means for fighting an ongoing bombing campaign over head from July onwards, it really doesn't match up well with this idea of thousands and thousands of planes and pilots are going to be ready and available to launch overwhelming waves of kamikaze attacks at an invading force later in the year. I suspect that a lot of these planned kamikazes were "paper" planes in terms of actually being serviceable and deployable.

 

[History Learner]

To be honest that's all really just restating the initial argument it didn't answer the questions, and frankly changing the kamikaze stats from ships sunk per plane to causalities inflicted just ask more questions

You've misunderstood, the statistic was always 6 planes to 1 aircraft. See OLYMPIC VS KETSU-GO, Marine Corps Gazette, August 1965, Vol. 49, No. 8:

"The greatest danger to the assault was assumed to come from the air. The Americans expected opposition from 5,000 kamikazes, a realistic estimate in keeping with Japanese plans (KETSU-GO Operation). These called for 5,000 planes to be expended in attacks on the invasion force, whose appearance was expected sometime after September. The Japanese estimated that the assault force would be carried in 1,000 transports and that if half were sunk in the first ten days the landings could be smashed. Using the 1:6 ratio derived from their Okinawa experience, Japanese planners estimated this would require 3,000 planes. They assigned an additional 350 kamikazes to attacks on the carrier forces. The remaining 1,650 included those under repair and lost before the attack. As late as 15 July, however, only 70% of the required planes were in hand so it seems reasonable to assume that aerial opposition would have been less than expected."​

1). if the average during Okinawa was 7 casualties per plane (including bombers not just kamikazes and bombers were more effective that kamikazes), then even 6,000 kamikaze attacks really isn't going to have the effect described (plus there's still the issues where are the kamikaze pilots going to come from going by your last posted figures that's all available pilots, despite the fact that pilots are being assigned other duties. Plus are the Japanese really going to use up all their pilots on downfall knowing that's not the last Japanese beach that will landed on).

3,000 planes at a 6:1 ratio results in 500 sunk ships. This is significant, as that's half of the entire invasion fleet's total of 1,000 transports; their logistics are crippled from the start. However, Japanese planning actually called for over 6,000 Kamikazes:

- 140 for air reconnaissance to detect the approach of the Allied fleet
- 6,225 kamikazes and conventional bombers to target the assault shipping
- 2,000 "air superiority" fighters to occupy the opposing CAP
- 330 conventional bombers flown by elite pilots to attack the carrier task group
- 150 further conventional bombers flown by elite pilots for a night attack on the US escort ships
- 100 paratroops carriers inserting approximately 1,200 commandos at US airfields on Okinawa, inspired by the relative success of a small-scale sortie months earlier

Giangreco notes that the Navy alone still had 2,450 rated high enough for night missions and 1,750 for dusk missions. Another 2,000 Army pilots had at least 70 hours of flight experience by the time of surrender. That's 6,200 trained pilots for 9,000 aircraft; even then, the Kamikaze pilots didn't need much training.

2)., The assertion that kamikaze attacks would suddenly become far more successful than they had been so far isn't supported. For instance hoping another 2,000 planes would become available form July 1945 on wards seems rather unlikely. Plus if there's not enough pilots it's irrelevant. It ignores the fact that there's going to be an ongoing air campaign against all these preparations. Not only will this campaign degrade these preparations but Japanese planes and more importantly pilots will be lost fighting it*. You still haven't supported why the big blue blanket won't work. The Japanese can't put 6,000 kamikaze planes on Kyushu a lot of these planes are going to be coming in from Honshu. And the US seem to have more than enough planes and ship cover in teh operation to counter it. These is I think a big issue in taking all possible planes in Japan (including the hoped for ones) in one total and all the planes the US have actually deployed and comparing them like that. It doesn't really work like that you have to look at deployable figures at any given time. There is a similar point about fuel reserves, the number of barrels the Japanese can scrape together in theory in July 1945, really isn't going to be the same amount actually available in airfields a few months later.

Quite frankly, it's clear to me with this part you didn't actually read what has been posted. We don't have to speculate whether or not the Japanese would have another 2,000 aircraft after July; they did. 12,684 aircraft of all types were accounted for in August 1945 by the Americans. Likewise, the same had been done for the oil; it was already stockpiled and on site. Pre-Invasion air campaigns had categorically failed to halt this rapid increase in Japanese aircraft, as the Japanese had constructed 60 airfields by August and this allowed a high degree of dispersion against American attacks which the Marine Corps Gazette notes greatly complicated American efforts in this regard.

As for the air attacks, we have every reason to predict the Kamikazes would work better here and you have failed to provide counter to such beyond dismissing it out of hand. The tactic the U.S. used at Okinawa was the "Big Blue Blanket", which called for picket ships hundreds of miles out and fighters up at all times. Unfortunately for the U.S. you cannot put picket ships hundreds of miles out when you're anchored off the immediate coast to unload troops and supplies; therefor, the U.S. would have no more than a few minutes warning, if that, of incoming Japanese air attack. Further, the U.S. during Okinawa never faced a situation where the Japanese would outnumber the defenders at 10:1. It doesn't matter if the U.S. Navy somehow miraculously launches every fighter and they all become aces that day; thousands of Japanese aircraft will get through.

Finally, even if we ignore the above and say they won't become more effective for some reason, using the Okinawa ratio still gets us to the end result of the entire transport portion of the invasion fleet being sunk, as previously shown, with the 6:1 ratio. Even if we arbitrarily say the Japanese do worse, for some reason, and say it takes 12:1 to sink a ship during OLYMPIC, that still gets us to their desired goal of half of the invasion fleet's transports sunk.

The last point the typhoon, that's going to effect defensive measures as well, and frankly a months delay is only going to worsen the Japanese position because it will be another month under a concerted air campaign but another month of preparations for the US who won't be. another point about US preparations, there seem to be lots of claims of the US were going to be surprised the US were ill-prepared etc., Only the US has by this point spent a few years planning and executing seaborne invasions, In N.Africa, Europe and the Pacific.

I'd recommend reading Gianreco; the Japanese had already stockpiled their supplies and delay would give them more time to raise and deploy more forces. The U.S. gets nothing out of it.

On the final point

"I emphasize again, there is no credible scholarship anywhere in the world who can seriously claim that an invasion of mainland Japan would have been anything short of a catastrophe; "

That a big claim because honestly most books I've read have said it was going to be bloody, but more due to winkling out entrenched committed defenders than kamikaze) and the us would have to heavily rely on air power to try and keep their one causalities down. But not to the point it couldn't be done. In general I think this does all boil down to the cardinal assertion that when the chips are down and men are dying the US can not withstand casualties like other countries do (The Japanese plans was certainly based on this). and frankly we saw that kind of thinking all throughout the war and it was never shown to be true. I guess it kind of depends on what you men by catastrophe, I mean yes anyone who thinks the US forces are going to land and taken Japan and have a nice time doing it is kidding themselves, and I can well believe it would be the campaign that would see the greatest US casualty numbers in the war

Again, read Gianreco. 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.

*this lasts brings up another point Where where all these Japanese pilots and planes during the strategic bombing campaign? Well they started off trying to fight it but what happened:

Air combat was most intense in late 1944 and early 1945. Following the first B-29 raids on Tokyo, the number of IJN aircraft assigned to air defense duties was greatly increased and all 12-centimeter (4.7 in) guns were allocated to protect the capital.[206] Fighters stationed to defend Japan's main industrial areas frequently intercepted American air raids between 24 November 1944 and 25 February 1945, and inflicted significant losses for a period. The number of fighters available declined from late January, however.[207] Poor coordination between the IJAAF and IJN also continued to hamper Japan's defensive efforts throughout this period.[208] The Americans suffered few losses from Japanese fighters during the night raids which were conducted from March 1945 until the end of the war.[209]
Resistance to the air raids decreased sharply from April 1945. On 15 April the IJAAF and IJN air defense units were belatedly placed under a single command when the Air General Army was formed under the command of General Masakazu Kawabe, but by this time the fighter force's effectiveness had been greatly reduced due to high rates of casualties in training accidents and combat. Due to the poor standard of the remaining pilots and the deployment of P-51 Mustangs to escort B-29s, the Japanese leadership decided in April to withdraw their remaining fighters from combat. These aircraft were placed in reserve to counterattack the Allied invasion.[210] As a result, few of the subsequent Allied raids were intercepted.[210] The effectiveness of Japanese anti-aircraft batteries also decreased during 1945 as the collapse of the national economy led to severe shortages of ammunition.[210] Moreover, as the anti-aircraft guns were mainly stationed near major industrial areas, many of the raids on small cities were almost unopposed.[211] Imperial General Headquarters decided to resume attacks on Allied bombers from late June, but by this time there were too few fighters available for this change of tactics to have any effect.[212] The number of fighters assigned to the Air General Army peaked at just over 500 during June and July, but most frontline units had relatively few serviceable aircraft.[213] During the last weeks of the war Superfortresses were able to operate with near impunity owing to the weakness of the Japanese air defenses; LeMay later claimed that during this period "it was safer to fly a combat mission over Japan than it was to fly a B-29 training mission back in the United States".[214]
Overall, Japanese fighters shot down 74 B-29s, anti-aircraft guns accounted for a further 54, and 19 were downed by a combination of anti-aircraft guns and fighters. IJAAF and IJN losses during the defense of Japan were 1,450 aircraft in combat and another 2,750 to other causes.[215]


Leaving aside what the above means for fighting an ongoing bombing campaign over head from July onwards, it really doesn't match up well with this idea of thousands and thousands of planes and pilots are going to be ready and available to launch overwhelming waves of kamikaze attacks at an invading force later in the year. I suspect that a lot of these planned kamikazes were "paper" planes in terms of actually being serviceable and deployable.

Again, read Gianreco. These Japanese pilots were not contesting the strategic bombing as IGHQ had decided to reserve them for KETSU-GO, the forthcoming decisive battle; this was done to preserve them as a fighting force and also to hopefully lull the U.S. into a false state of security.

 

[TDM]

You've misunderstood, the statistic was always 6 planes to 1 aircraft. See OLYMPIC VS KETSU-GO, Marine Corps Gazette, August 1965, Vol. 49, No. 8:

"The greatest danger to the assault was assumed to come from the air. The Americans expected opposition from 5,000 kamikazes, a realistic estimate in keeping with Japanese plans (KETSU-GO Operation). These called for 5,000 planes to be expended in attacks on the invasion force, whose appearance was expected sometime after September. The Japanese estimated that the assault force would be carried in 1,000 transports and that if half were sunk in the first ten days the landings could be smashed. Using the 1:6 ratio derived from their Okinawa experience, Japanese planners estimated this would require 3,000 planes. They assigned an additional 350 kamikazes to attacks on the carrier forces. The remaining 1,650 included those under repair and lost before the attack. As late as 15 July, however, only 70% of the required planes were in hand so it seems reasonable to assume that aerial opposition would have been less than expected."​

3,000 planes at a 6:1 ratio results in 1,500 sunk ships. This is significant, as that's half of the entire invasion fleet of 3,000 transports; their logistics are crippled from the start. As for the breakdown of Japanese planes:

- 140 for air reconnaissance to detect the approach of the Allied fleet
- 6,225 kamikazes and conventional bombers to target the assault shipping
- 2,000 "air superiority" fighters to occupy the opposing CAP
- 330 conventional bombers flown by elite pilots to attack the carrier task group
- 150 further conventional bombers flown by elite pilots for a night attack on the US escort ships
- 100 paratroops carriers inserting approximately 1,200 commandos at US airfields on Okinawa, inspired by the relative success of a small-scale sortie months earlier

Giangreco notes that the Navy alone still had 2,450 rated high enough for night missions and 1,750 for dusk missions. Another 2,000 Army pilots had at least 70 hours of flight experience by the time of surrender. That's 6,200 pilots for 9,000 aircraft; even then, the Kamikaze pilots didn't need much training.

No I have not misunderstood the stat I already addressed the 6:1 planes to ships in my first post, the actual figures don't support the claim. You then switched to causalities per plane and well see my last post on that.

Plus as per my posts 6000 pilots and 6000 kamikaze attacks really does mean no other air force than kamikaze! Once they're used up more planes don't matter! kamikaze pilots can't be both kamikaze pilots and piloting 2000 Air superiority fighters.

I suggest we tackle this before we go on to the rest, (although I already tacked the assumption of Kamikazes working better, air cover and the air campaigns you have not answered by my points just repeated your assertions)

One thing though I don't know where the 880k dead and missing and 2.5m wounded for Olympic comes from. even if we take the ratios as read (just maybe the US learns from Okinawa etc) that doesn't match the estimates using those ratios even if you increase the operational time.

 

[pjmidd]

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:

1. 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.
2. 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.
3. The Japanese had 60 airfields on Okinawa 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.

At least get your stats right , 6:1 was hits not sinking. Overall its around 1460 vs 33 ( sunk or out of action) for Okinawa so 44:1. Over the entire war its normally estimated at around 2800 vs 47 sunk , 368 damaged so 60:1 on sinkings.

 

[History Learner]

No I have not misunderstood the stat I already addressed the 6:1 planes to ships in my first post, the actual figures don't support the claim. You then switched to causalities per plane and well see my last post on that.

I never once did and I challenge you to cite where I did.

As for the matter of 6:1, it's because your sources aren't distinguishing between the 500 Army planes that were not Kamikazes, nor accounting for the 879 planes that returned to base after not finding a target or completing an alternative mission but were still counted as part of Operation Kikisui.

Plus as per my posts 6000 pilost and 6000 kamikaze attacks really does mean no other air force than kamikaze! Once they're used up more planes don't matter! kamikaze pilots can't be both kamikaze pilots and piloting 2000 Air superiority fighters.

Or maybe the well trained pilots would be used for the air superiority missions while the lesser trained pilots would be the Kamikazes, as would be logical? To quote Gianreco:

"Readers of this volume will find that misconceptions abound as to the state of Japanese readiness to meet the invasion. This principally is due to the uncritical acceptance of assumptions and incomplete intelligence in the relatively few presurrender documents that have formed the core of many scholars’ opinions. The state of Japanese air power is an excellent case in point. The often-repeated common wisdom holds that there were only 5,500, or at most 7,000, aircraft available and that all of Japan’s best pilots had been killed in earlier battles. What the U.S. occupation forces found after the war, however, was that the number of aircraft exceeded 12,700, and thanks to the wholesale conversion of training units into kamikaze formations, there were some 18,600 pilots available. Most were admittedly poor flyers, but due to the massive influx of instructors into combat units, more than 4,200 were rated high enough for either twilight or night missions. A deadly turn of events."​

I suggest we tackle this before we go on to the rest, (although I already tacked the assumption of Kamikazes working better, air cover and the air campaigns you have not answered by my points just repeated your assertions)

You only dismissed it out of hand, you did not tackle anything. As I said, the U.S. Anti-Kamikaze tactic was the Big Blue Blanket, which would not function on Okinawa; you cannot have picket ships hundreds of miles out when you are parked off the enemies shore to unload troops and supplies. Please explain to me how you don't expect the U.S. to do even worse when it's only tactic is removed from it? Even then, if you wish to take the Japanese as only doing the same as they did on Okinawa-6:1-you still end up with all of the transports sunk.

One thing though I don't know where the 880k dead and missing and 2.5m wounded for Olympic comes from. even if we take the ratios as read (just maybe the US learns from Okinawa etc) that doesn't match the estimates using those ratios even if you increase the operational time.

From the JCS formulas of April, 1945. What's funny is that this already grim scenario was taken before the experience of Okinawa; after, the casualty projections became much worse. According to Downfall: The End of the Imperial Japanese Empire by Richard Frank, William Shockley's study for Secretary of War Henry Stimson in the Summer of '45 projected 1.7–4 million American casualties, of whom 400,000–800,000 would be fatalities.

 

[TDM]

I never once did and I challenge you to cite where I did.

here:

.....

From the experience at Okinawa, the loss or expenditure of 1,430 bombers and kamikaze aircraft by the Japanese Army and Navy caused about 10,000 casualties, half of them deaths, to American and British forces, or about 7 casualties per Japanese aircraft committed.

,,,,,

As for the matter of 6:1, it's because your sources aren't distinguishing between the 500 Army planes that were not Kamikazes, nor accounting for the 879 planes that returned to base after not finding a target or completing an alternative mission but were still counted as part of Operation Kikisui.

No the stats are clear you are conflating hitting with sinking, but hitting is not automatically sinking, ironically some of those planes that weren't kamikazes were bombers who where better at causing damage so actually the reverse effect is true when looking solely at kamikazes.

Or maybe the well trained pilots would be used for the air superiority missions while the lesser trained pilots would be the Kamikazes, as would be logical? To quote Gianreco:

Yes it would, only you are still counting them in your kamikaze figures, hence my point that I have made several times now about if all 6000 are kamikaze they can't be anything else, and conversely if less than 6000 of them are kamikaze than you will have less than 6000 kamikazes.

also now you are claiming 18,600 pilots?! Man pick a figure yeah (also frankly I love to see the actual cite for that as that is now a ridiculous number of trained combat pilots!)

You only dismissed it out of hand, you did not tackle anything. As I said, the U.S. Anti-Kamikaze tactic was the Big Blue Blanket, which would not function on Okinawa; you cannot have picket ships hundreds of miles out when you are parked off the enemies shore to unload troops and supplies. Please explain to me how you don't expect the U.S. to do even worse when it's only tactic is removed from it? Even then, if you wish to take the Japanese as only doing the same as they did on Okinawa-6:1-you still end up with all of the transports sunk.

And you have not responded to my points refuting you claim of it not working. And I'm not going any further on this until you do. But again since they never sunk 1 ship for every 6 kamikazes in Okinawa you are just wrong in that claim.

From the JCS formulas of April, 1945. What's funny is that this already grim scenario was taken before the experience of Okinawa; after, the casualty projections became much worse. According to Downfall: The End of the Imperial Japanese Empire by Richard Frank, William Shockley's study for Secretary of War Henry Stimson in the Summer of '45 projected 1.7–4 million American casualties, of whom 400,000–800,000 would be fatalities.

No I linked directly to the ratio work directly (which did take Okinawa into account again as per my link), your figures using that work and claiming 880k dead/missing in Olympic are wrong.

 

[TDM]

Just to say again I'm not saying Olympic and Coronet would be cake walks, these would be without doubt the bloodiest campaigns US forces would undertake in WW2 if they happened. But there is a tendency to overstate the case, as well as overstate the US's intolerance for casualties which is IMO is often linked to this.

I'm definitely in the Nuclear bombs saved both US and Japanese lives camp!

However I originally posted in this thread regarding the effectiveness of Kamikaze attacks, which were a weapon of desperation and the effects of which are most definitely are over stated at times.

 

[DragonsInAmerica]

I'd agree that the nukes saved a lot of lives - not just American and Japanese lives during WWII. Nukes and mutually assured destruction meant that war would lead to the destruction of mankind, so no one wanted to risk starting one.

Anyways, I'm getting off topic. I heard the Japanese citizens were starving by summer 1945, so the nukes and surrender of Japan saved their lives. If that never happened and the Americans invaded Japan in '45-'46, I'd expect starvation and disease for the civilians and atrocities on both sides. American GIs will kill Hirohito, assuming he didn't die already from a coup or whatever. This will lead to revolt from the Japanese during and after the invasion, and the Americans will not treat them kindly (especially with the racist dehumanizing propaganda of the time). I agree that at the very least (AKA the best-case scenario for the civilians), 50% of the civilians will die. IJ soldiers who surrender will be treated like trash, especially if all American POWs are killed once Olympic starts. (Hence atrocities on both sides.) Thus, IJ soldiers are more likely to launch desperate suicide attacks (see: Makin Island, Guadalcanal, Battle of Attu, Battle of Saipan... but NOT at Iwo Jima? Yes for Okinawa, though. You folks can discuss the effectiveness of banzai charges. I heard they weren't very effective). Disregard for the rules of warfare will mean that each side will do anything to beat back the enemy, including the use of CBRNs, minus the N and the R. (That came out wrong... uh... Is it NBC weapons, minus the N?) Basically, mass murder weapons will be used. Like mustard or phosphine gas. (I'm not a gassing expert, don't pester me for more information.)

The civilians will be caught in the crossfire. Many will be pressured by peers to attack American soldiers, and everyone knows what peer pressure can do. (See the kamikaze video I linked on the second page.) Civilians might organize banzai charges of their own. People too cowardly/sensible (depending on your perspective) will hide/run/surrender. But hiding civilians will be flushed out by gas/flamethrowers from their homes/caves, there's no running from an island (some lucky refugees might be able to leave by boat, although I can't imagine where they'll go) and surrendering to the Americans means the equivalent of the Bataan Death March is waiting in store for the citizens.

The luckiest might hide in the tallest mountain peaks of Japan or something.

Anyways, here are some statistics. I'm not sure how relevant non-Japanese casualties are to Downfall, but it might be useful:

Spoiler: Some casualty percentages

"David Glantz in his book "When Titans Clashed" puts the total German casualties (including wounded) at over 11 million (6 million wounded, 5 million dead). 11 million was 75% of the entire German Army and 46% of the German male population in 1939." (emphasis added)

That's about 23% of the whole German population (assuming females and males are equally abundant).

(For the figures you're seeing below, I just searched up population rates pre-war and casualty rates, and did some division.)

As of 1939, the Soviet population was 170.5 million people. Soviet losses are around 27 million, so that's an overall death rate of about 15.8%.

6 million Poles died from WWII, mostly civilians. The 1939 population was 35.1 million, making their death rate around 17.1%. (Figures come from Googling)

This chart might help, although I'm not sure how it's supposed to be read:

 

[History Learner]

here:

No where in the quoted portion did I use the 6:1 ratio but was instead talking about the casualties incurred. From my very own opening post, however:

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.

No the stats are clear you are conflating hitting with sinking, but hitting is not automatically sinking, ironically some of those planes that weren't kamikazes were bombers who where better at causing damage so actually the reverse effect is true when looking solely at kamikazes.

True, I did get it confused sinkings/hitting, but mission kill is a thing. A burning transport can't exactly unload troops and I shutter to think what a supply ship loaded with ammunition would look like. And no, once you account specifically for the actual Kamikazes, you don't see this.

Yes it would, only you are still counting them in your kamikaze figures, hence my point that I have made several times now about if all 6000 are kamikaze they can't be anything else, and conversely if less than 6000 of them are kamikaze than you will have less than 6000 kamikazes.

also now you are claiming 18,600 pilots?! Man pick a figure yeah (also frankly I love to see the actual cite for that as that is now a ridiculous number of trained combat pilots!)

No, you asked where all the pilots for this came from and showed there was at least 6,200 pilots that I could account for off the top of my head. Most likely, as I said in the quoted bit, the trained ones would be reserved for the more conventional missions. As for the 18,000 pilots in total, that citation was literally given in the post; it's from Hell to Pay by Gianreco. Here's a citation I could find online, since I've already quoted the relevant section from my own copy; just in case, I'll even add a screenshot.

And you have not responded to my points refuting you claim of it not working. And I'm not going any further on this until you do. But again since they never sunk 1 ship for every 6 kamikazes in Okinawa you are just wrong in that claim.

Sure, I confused hits with sinkings; I apologize. With 6,255 Kamikaze, that's still 20% of the invasion fleet using the 44:1 one ratio.

No I linked directly to the ratio work directly (which did take Okinawa into account again as per my link), your figures using that work and claiming 880k dead/missing in Olympic are wrong.

The link you provided is dead, taking me to no in book citation but instead to the cover page of some alternate history novel. That is not an academic source by any means, nor does it refute me citing a study conducted on behalf of no less than the Secretary of War in the Summer of 1945, after Okinawa was finished. Outside of this study and using the JCS formulas from April, we can also use General Willoughby's "Sinister Ratio", which was informed by the experience of Okinawa. Willoughby found that 2 to 2.5 Japanese divisions could extract 40,000 U.S. casualties; in effect, a 1:1 ratio. To put this into context, OLYMPIC was to feature 14 Divisions with no provisions for follow up formations against 19 to 21 Japanese Divisions or equivalents.

What makes Willoughby's estimation all the more terrifying is that it's only factoring in IJA ground groups; the 20 Million civilians to be armed, and any IJN or IJAAF personnel pressed into ground service are not included. Let that sink in for a moment.

Edit: I think the source of the confusion is that I said OLYMPIC when I meant DOWNFALL in that post, my bad.

 

[Eric C Johnson]

That sized Australian force would require significant shipping to move it from Australia to Japan. I don't doubt it would be possible but it would be a significant burden on the Allies part. Then you have the problem of logistics for such a force. They all used a different calibre small arms compared to the American forces, as well as artillery and AFVs. Providing the required amount of back up, once they had landed and were engaged in combat would be again, a significant burden. Australia tended to pay it's own logistic costs, however it lacked the transport to supply such a force let alone move it. BCOF (British Commonwealth Occupation Forces) proved too expensive for the British, let alone the Australians. Which is why they were being wound down at the outbreak of the Korean War.

My apologies. I was using the contemporary Commonwealth nomenclature in identifying units which was to leave off the "rd" on 3rd British Division and the "th" on 6th Canadian and 10th Australian Divisions. There were only three divisions allocated X Commonwealth Corps, not 19. The error is mine alone. The shipping for only one Division (10 Australian) is comparable to that used by either 7 or 9 Australian Divisions in their respective amphibious assaults on Borneo in June 1945.

As an aside, The British-Indian Division sent to Japan in February 1946 contained 268 Indian Lorried Infantry Brigade, 25 British Infantry Brigade, 34 Australian Brigade and 9 New Zealand Brigade, and 7 Indian Cavalry Regiment (Stuart V tanks). The Indian troops were withdrawn in September 1947 in consequence to independence the previous month, and the small Indian staff element at in divisional level did likewise. Ironically, the name of the division did not change. 2 New Zealand Divisional Cavalry Regiment left in August 1947, and the rest of the brigade in December. 25 British Infantry Brigade also withdrew in December as an austerity measure, but British staff officers remained. 34 Australian Brigade was disbanded in October 1948, and the division folded up a month later. 3/Royal Australian Regiment remained behind until September 1950, when it went to Korea. Combined with RAN rotations, cruisers HMAS Shropshire, Hobart, Australia and Hobart again until September 1947; and generally one destroyer and one frigate during the entire period of September 1945-September 1950; the Australians contributed the most to Commonwealth Occupation forces in Japan.

 

[Rickshaw]

My apologies. I was using the contemporary Commonwealth nomenclature in identifying units which was to leave off the "rd" on 3rd British Division and the "th" on 6th Canadian and 10th Australian Divisions. There were only three divisions allocated X Commonwealth Corps, not 19. The error is mine alone. The shipping for only one Division (10 Australian) is comparable to that used by either 7 or 9 Australian Divisions in their respective amphibious assaults on Borneo in June 1945.

As an aside, The British-Indian Division sent to Japan in February 1946 contained 268 Indian Lorried Infantry Brigade, 25 British Infantry Brigade, 34 Australian Brigade and 9 New Zealand Brigade, and 7 Indian Cavalry Regiment (Stuart V tanks). The Indian troops were withdrawn in September 1947 in consequence to independence the previous month, and the small Indian staff element at in divisional level did likewise. Ironically, the name of the division did not change. 2 New Zealand Divisional Cavalry Regiment left in August 1947, and the rest of the brigade in December. 25 British Infantry Brigade also withdrew in December as an austerity measure, but British staff officers remained. 34 Australian Brigade was disbanded in October 1948, and the division folded up a month later. 3/Royal Australian Regiment remained behind until September 1950, when it went to Korea. Combined with RAN rotations, cruisers HMAS Shropshire, Hobart, Australia and Hobart again until September 1947; and generally one destroyer and one frigate during the entire period of September 1945-September 1950; the Australians contributed the most to Commonwealth Occupation forces in Japan.

Your apology is accepted. 3 Battalion, RAR would normally be expressed as "3 RAR" not 3/ Royal Australian Regiment ( I assume that is an American version of what it would have been called). I served for several years with a WO1, a veteran of 3 RAR from BCOF and Korea. He had some interesting stories to tell.

 

[TDM]

No where in the quoted portion did I use the 6:1 ratio but was instead talking about the casualties incurred. From my very own opening post, however:

I didn't say you did in that quoted portion. I was talking about the casualty ratios, you asked me to show you where you had made that claim and I did.

You've made two statistical claims for the effectiveness of kamikazes

first 6:1 for sinking

and then 1:7 for casualties

True, I did get it confused sinkings/hitting, but mission kill is a thing. A burning transport can't exactly unload troops and I shutter to think what a supply ship loaded with ammunition would look like. And no, once you account specifically for the actual Kamikazes, you don't see this.

Only a hit also doesn't actually mean a mission kill either, the kamikaze/casualty ratio shows this.

No, you asked where all the pilots for this came from and showed there was at least 6,200 pilots that I could account for off the top of my head. Most likely, as I said in the quoted bit, the trained ones would be reserved for the more conventional missions.

No I asked how can the 6000 pilots you quoted be 6000 kamikazes but also air superiority fighters, bombers recon, transport etc.

As for the 18,000 pilots in total, that citation was literally given in the post; it's from Hell to Pay by Gianreco. Here's a citation I could find online, since I've already quoted the relevant section from my own copy; just in case, I'll even add a screenshot.

View attachment 566138

I think the problem I have with this is it's basically the sum total of all pilots and air crews in uniform in Japan when the treaty is signed, that's really not the thing as all pilots that will be kamikazes in Oct 1945 after a continued bombing campaign. I buy the 6200 figure as good ball park figure earlier because that was from actual relevent pilots at the time. either way even if there were 18,000 pilots planes then become the limiting factor.

Sure, I confused hits with sinkings; I apologize. With 6,255 Kamikaze, that's still 20% of the invasion fleet using the 44:1 one ratio.

No worries but hang on how can it have been 50% of the fleet at 6:1 (your initial claim) and now 20% of the fleet at 44:1?

44:1 is 7.3x less effective than 6:1

another way to put this all in context is at Okinawa the Japanese flew 2550 kamikaze attacks, so even if they threw all 6000 out at Olympic and everything else is equal you will get 2.4x the effect


Or if you go back to the 7 casualties per kamikaze attack you see how kamikazes really are not going to bethe wonder weapon it's often portrayed as.

The link you provided is dead, taking me to no in book citation but instead to the cover page of some alternate history novel. That is not an academic source by any means, nor does it refute me citing a study conducted on behalf of no less than the Secretary of War in the Summer of 1945, after Okinawa was finished. Outside of this study and using the JCS formulas from April, we can also use General Willoughby's "Sinister Ratio", which was informed by the experience of Okinawa. Willoughby found that 2 to 2.5 Japanese divisions could extract 40,000 U.S. casualties; in effect, a 1:1 ratio. To put this into context, OLYMPIC was to feature 14 Divisions with no provisions for follow up formations against 19 to 21 Japanese Divisions or equivalents.

What makes Willoughby's estimation all the more terrifying is that it's only factoring in IJA ground groups; the 20 Million civilians to be armed, and any IJN or IJAAF personnel pressed into ground service are not included. Let that sink in for a moment.

The link I gave is too "What if", but the pages in question are using the joint chiefs ratios (the same ones you cited and used earlier) 1.78 killed, 0.18 missing 5.5 wounded per 1000/day.

TBH all I did was a google search on the term "Joint Chiefs formally adopted a pair of ratios in April 1945 based on experiences in both Europe and the Pacific" which I lifted from your same post.

Edit: I think the source of the confusion is that I said OLYMPIC when I meant DOWNFALL in that post, my bad.

No worries but hence my questions about why would the Japanese expend all their kamikazes in what would be the first of two or more seaborne invasions, and the US invasion air cover.

 

[History Learner]

I didn't say you did in that quoted portion. I was talking about the casualty ratios, you asked me to show you where you had made that claim and I did.

You've made two statistical claims for the effectiveness of kamikazes

first 6:1 for sinking

and then 1:7 for casualties

I think we may be talking past each other on this point; I was responding to this:

No I have not misunderstood the stat I already addressed the 6:1 planes to ships in my first post, the actual figures don't support the claim. You then switched to causalities per plane and well see my last post on that.

As you note here, I did not "switch" but rather presented both, in that more context was being given to the 6:1 ratio.

Only a hit also doesn't actually mean a mission kill either, the kamikaze/casualty ratio shows this.

It doesn't necessitate such, no, but there will be many even if ships aren't sunk. Seen the USS Franklin, for a case of this.

No I asked how can the 6000 pilots you quoted be 6000 kamikazes but also air superiority fighters, bombers recon, transport etc.

Yes, you asked where all the pilots for this were and cited the 6,200 trained pilots I was already aware of, in that there was the basis for doing the Kamikaze strikes. I did not mean that they would waste all of their trained pilots on that, but rather was I responding directly to your question.

I think the problem I have with this is it's basically the sum total of all pilots and air crews in uniform in Japan when the treaty is signed, that's really not the thing as all pilots that will be kamikazes in Oct 1945 after a continued bombing campaign. I buy the 6200 figure as good ball park figure earlier because that was from actual relevent pilots at the time. either way even if there were 18,000 pilots planes then become the limiting factor.

Yes, not all of those pilots would be Kamikazes and that's why I cited all the other planes reserved for other missions. And sure, there's not enough planes for all of them, but there is enough planes for the Japanese objectives and planning structure for OLYMPIC. As Gianreco notes, Kyushu was getting the priority.

No worries but hang on how can it have been 50% of the fleet at 6:1 (your initial claim) and now 20% of the fleet at 44:1?

44:1 is 7.3x less effective than 6:1

another way to put this all in context is at Okinawa the Japanese flew 2550 kamikaze attacks, so even if they threw all 6000 out at Olympic and everything else is equal you will get 2.4x the effect

6:1 was, as noted, the hit ratio, not the sinking ratio, which was the mistake I made in mis-remembering. 44:1, as another user pointed out, was the actual ratio to sinkings.

I also need to point out, again, that there was not 2,550 Kamikaze attacks for Okinawa. That figure include 500 IJAAF planes that were on more conventional missions included in the total and over 800 aborts by actual Kamikazes; the real figure is, as previously noted. ~1,400.

6,225/44 = 142 sinkings.

Or if you go back to the 7 casualties per kamikaze attack you see how kamikazes really are not going to bethe wonder weapon it's often portrayed as.

6,255 x 7 = 43,785 casualties

To put that into perspective, casualties for Iwo clocked in at 20,000. Even assuming no improvements in the ratio, and Gianreco goes into great detail about how the Japanese were improving themselves in this regard, Kamikazes alone could very easily cripple the logistics of the invasion and remove several U.S. divisions from the board.

The link I gave is too "What if", but the pages in question are using the joint chiefs ratios (the same ones you cited and used earlier) 1.78 killed, 0.18 missing 5.5 wounded per 1000/day.

TBH all I did was a google search on the term "Joint Chiefs formally adopted a pair of ratios in April 1945 based on experiences in both Europe and the Pacific" which I lifted from your same post.

I haven't seen the page, but I'll take the claim at face value. The book in question isn't an academic one, but a fictional one. Here is an academic one:

"While strategic planners were reluctant, for good reason, to commit estimates for the balance of the war to paper, they frequently set down short-term estimates of one to three months as benchmarks for analyzing differing interpretations of factors affecting future manpower losses, and also approached the question by examining loss ratios from the preceding year of combat. The JCS history of its wartime activities notes that planners “pointed out . . . that in seven amphibious campaigns in the Pacific the casualty rate had run 7.45 per thousand per day; whereas, in the protracted land warfare in the European Theater of Operations it had only been 2.16.”^65 Ongoing intelligence estimates, coupled with the 7.45 / 2.16 comparison, and a total of 64,391 soldiers and Marines killed and wounded to take an amount of land half the size of wartime Detroit --- Iwo Jima and the main battle area on Okinawa^66 --- were largely responsible for the increase."​

No worries but hence my questions about why would the Japanese expend all their kamikazes in what would be the first of two or more seaborne invasions, and the US invasion air cover.

Because that's exactly what their planning called for and it fits entirely within their doctrine of decisive battle. Their hope was to defeat or so bloody the U.S. in OLYMPIC that they (the U.S.) would seek peace. General Marshall and others were definitely concerned in this regard and U.S. media was being pretty closely followed by the Japanese in 1944-1945, with Tokyo noticing the great pains the War Department was going to obscure existing casualties.

 

[CV12Hornet]

"I emphasize again, there is no credible scholarship anywhere in the world who can seriously claim that an invasion of mainland Japan would have been anything short of a catastrophe; "

That a big claim because honestly most books I've read have said it was going to be bloody, but more due to winkling out entrenched committed defenders than kamikaze) and the us would have to heavily rely on air power to try and keep their one causalities down. But not to the point it couldn't be done. In general I think this does all boil down to the cardinal assertion that when the chips are down and men are dying the US can not withstand casualties like other countries do (The Japanese plans was certainly based on this). and frankly we saw that kind of thinking all throughout the war and it was never shown to be true. I guess it kind of depends on what you men by catastrophe, I mean yes anyone who thinks the US forces are going to land and taken Japan and have a nice time doing it is kidding themselves, and I can well believe it would be the campaign that would see the greatest US casualty numbers in the war

Frankly, even if the Japanese air forces fail to sink a single invasion transport, trying to conduct an amphibious landing while outnumbered against an opponent with more accurate intelligence than you and your air and naval power are all tied up is a recipe for disaster. The Dieppe raid was exactly such a disaster - except there the Allies actually outnumbered the local German troops seven to one.

Some of the loss of numerical superiority would be made up by the great strides the Allies had made in conducting large-scale amphibious operations, but that's not nearly enough.

 

[History Learner]

Frankly, even if the Japanese air forces fail to sink a single invasion transport, trying to conduct an amphibious landing while outnumbered against an opponent with more accurate intelligence than you and your air and naval power are all tied up is a recipe for disaster. The Dieppe raid was exactly such a disaster - except there the Allies actually outnumbered the local German troops seven to one.

Some of the loss of numerical superiority would be made up by the great strides the Allies had made in conducting large-scale amphibious operations, but that's not nearly enough.

It's honestly scary how accurate Japanese intelligence was on OLYMPIC. To quote Gianreco:

"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."​

 

[LeX]

4. Resistance to the Soviet invasion of Manchuria after 14 August 1945 would have been fierce, but not have affected the eventual outcome. However, with the investment of additional time and a much higher butcher’s bill; it is likely that Josef Stalin would refuse to return Manchuria to Nationalist China. The USSR never broke diplomatic relations with the puppet government of Manchukuo, and characterized its invasion as the result of an “invitation” from the people of Manchuria to depose their Japanese overlords. The longer that fiction remains in place, (that is until the eventual surrender of Japan), the easier for the USSR to keep Manchukuo as a puppet state, eventually becoming a part of Stalin’s insatiable appetite for territory. The split between Soviet and Chinese Communists is likely in 1946, not the late 1950’s.

I don't think so. Stalin only took territory when it presented a clear geopolitical advantage and would not ruffle too many feathers. Manchuria was nonviable in its 1945 form, with the vast majority of the population being Han Chinese and the Empire of Manchukuo having no popular legitimacy. Stalin's attitude toward KMT-ruled China was that it was a useful buffer that Moscow should maintain friendly relations with, while quietly supporting the local communists, whom no on expected to win so rapidly and totally in the Chinese Civil War. Had the defeat of Japan been delayed, Manchuria would probably just become a stronger CCP base area. With the KMT forces busy handling the Japanese in eastern China, Chiang Kai-shek may never have gotten the chance to try sending his best troops north in a foolhardy attempt to recover Manchuria, and China might end up split between north and south.