WW2 lasts untill 1946

[Cjc]

The idea is what would change the war had kept going with an invasion of Japan (which was going to take until mid 46 at the earliest it could have very easily lasted until 47).

For example would the US have biult more midway and essexs class carriers if the war had lasted of another year.

There probably isn't going to be a korean war simply because the us wasn't interested in occupying south korea until after Japan surrendered so Kim il sung is probably getting all of korea without a fight.

Would the uk have built malta class carriers if they were still at war for an extra year.

Things like this.

 

[DWG]

The idea is what would change the war had kept going with an invasion of Japan (which was going to take until mid 46 at the earliest it could have very easily lasted until 47).

How long Japan lasts will be substantially dependent on when Russia decides to open hostilities and how fast the Kwantung Army collapses. If Japan loses the resources it's getting from China as well as those cut off by the Allied blockade then it's entire ability to continue as a combatant power is likely compromised.

For example would the US have biult more midway and essexs class carriers if the war had lasted of another year.

It's not so much would they have built more as would they have stopped the various cancellations, the building programme was already in place, and the run-down had started before VJ-Day. In the UK even under the assumption the war would continue into 1946 (or '47?), the cancellations started on the basis of when vessels were likely to commission. If they wouldn't commission before the assumed end of the war, then was there any point in completing them. Two of the 6 planned Midways were cancelled in March 1945, as were six Essexes (the other cancelled Midway was cancelled in 1943).

Even if they had continued the building programme, the Essexes took about 18-21 months from keel laying to commissioning, so even if started in March 1945 (unlikely) the additional Essexes (CV50 to 55) would not have been commissioned until very late in '46. Any further additions to the programme would be even later. OTOH at least some of the seven Essexes completed post-war, plus Reprisal and Iwo Jima, would have become available. Similarly Coral Sea, the third Midway, would likely have commissioned in mid-late 1946.

There probably isn't going to be a korean war simply because the us wasn't interested in occupying south korea until after Japan surrendered so Kim il sung is probably getting all of korea without a fight.

The Japanese forces in Korea might have some objections.

Would the uk have built malta class carriers if they were still at war for an extra year.

No, the final Malta proposal was sent for Board Approval in March 1945, with approval deferred in August. Even if it had been approved in March it would have required the completion of detailed design, delaying laying down until late 1945, and then a minimum of a couple of years of building work, meaning they would be unlikely to reach the Far East until 1948.

What would have reached the British Pacific Fleet were Vanguard, the Colossus and Majestic class light fleet carriers, the Minotaur class CLs, the 1942 Battle Class destroyers and the A class submarines. What might have reached the Fleet were the 1943 and 1944 Battles, the Weapons, and just potentially the Darings and the Neptune class CLs.

 

[Scott Kenny]

How long Japan lasts will be substantially dependent on when Russia decides to open hostilities and how fast the Kwantung Army collapses. If Japan loses the resources it's getting from China as well as those cut off by the Allied blockade then it's entire ability to continue as a combatant power is likely compromised.

Exactly.

It's not so much would they have built more as would they have stopped the various cancellations, the building programme was already in place, and the run-down had started before VJ-Day. In the UK even under the assumption the war would continue into 1946 (or '47?), the cancellations started on the basis of when vessels were likely to commission. If they wouldn't commission before the assumed end of the war, then was there any point in completing them. Two of the 6 planned Midways were cancelled in March 1945, as were six Essexes (the other cancelled Midway was cancelled in 1943).

Right, so it's likely that there would be 2 more Midways and maybe all 6 of those new Essex-class. It'd be better if any of those had already been laid down, though.

The Japanese forces in Korea might have some objections.

More than "some", and I suspect the debate would be quite "energetic."

No, the final Malta proposal was sent for Board Approval in March 1945, with approval deferred in August. Even if it had been approved in March it would have required the completion of detailed design, delaying laying down until late 1945, and then a minimum of a couple of years of building work, meaning they would be unlikely to reach the Far East until 1948.

I think they'd still get laid down and built.

 

[Dilandu]

The obvious result would be a death of millions of Japanese civilians. Japan was already on the brink of starvation, due to lack of fuel, disruption of logistic, devastation of the industry, and simply bad yields. The invasion would disrupt whatever supplies left, causing civilian casualties on the scope of 10-12 millions.

 

[Dilandu]

How long Japan lasts will be substantially dependent on when Russia decides to open hostilities and how fast the Kwantung Army collapses.

Most likely the same time. Kwantung army was, simply and clearly, outclassed too much. They were totally unprepared to fight 1945-esque warfare - against literally the best and most experienced land army in the world at this time. Also, the Kwantung Army by 1945 was a shadow of itself; during the later years of war, its best divisions were removed either to fight in China or to protect Japan homeland, and replaced with hastily formed "new" divisions, composed of railroad guards, border patrols, police, ect. They still have good fortifications to rely on, but lacked modern weapons, ammunition, and their tactics (as well as understanding of modern tactics) was hopelessly obsolete. Japanese higher ranks essentially viewed Kwantung Army in 1945 as more deterrence, than actual defense. They hoped that as long as it looks big and strong on paper, USSR would be reluctant to enter the war with Japan.

The Japanese forces in Korea might have some objections.

Their objections wouldn't mean much, frankly. AFAIK Korea wasn't heavily defended, since it was viewed as "safe rear" of the Japanese Empire. Most of defenses there were oriented against naval attacks, not overland invasion from Manchuria.

 

[Scott Kenny]

Any Soviet assault would likely require transporting those divisions that had conquered Germany all the way East. Even assuming a fully-functional Trans-Siberian Railroad, a Rail March like that would likely be 6 months to a year. So, call it August 45 when the replacing divisions arrive and relieve the conquering divisions, then the conquering divisions arriving around Manchuria/Vladivostok maybe as early as February but probably be ready to start fighting closer to April 46 due to winter weather causing delays.

Yes, the Soviets had divisions in Siberia, but as I understand it just enough to prevent the Japanese from advancing. (Also, IIRC many of the Conquering divisions had originally been raised back in Siberia, then shipped west to replace those divisions wiped out in 42-43.)

 

[Dilandu]

Yes, the Soviets had divisions in Siberia, but as I understand it just enough to prevent the Japanese from advancing. (Also, IIRC many of the Conquering divisions had originally been raised back in Siberia, then shipped west to replace those divisions wiped out in 42-43.)

Not sure I understood your point. The Soviet troops on Far East were partially composed of divisions from Europe, partially from the forces that stayed on Far East during the war. For example, the 1st Red Banner Army was based on Far East from 1938 to 1945, most of its divisions were from Far East too (in 1941-1942 they detached part of personnel to West, but themselves weren't moved). On the other hand, 5th Army was formed on West in 1941, fought the whole war, in April 1945 was placed in Stavka's reserce and then transported to Far East.

Any Soviet assault would likely require transporting those divisions that had conquered Germany all the way East. Even assuming a fully-functional Trans-Siberian Railroad, a Rail March like that would likely be 6 months to a year. So, call it August 45 when the replacing divisions arrive and relieve the conquering divisions, then the conquering divisions arriving around Manchuria/Vladivostok maybe as early as February but probably be ready to start fighting closer to April 46 due to winter weather causing delay

Those divisions started to get transported to Far East since the beginning of 1945. About 1/3 of all troops, about half of tanks and planes used in Soviet-Japanese war were transported from West to Far East.

 

[Justo Miranda]

What if the Hiroshima bomb had not exploded, being captured by the Japanese?

What if the typhoon of 1946 had destroyed the invasion fleet of Operation Olympic?

What if the U-Boats had dropped Reichenberg manned bombs on Washington?

What if the IJN's aircraft carrier submarines had destroyed the Atlantic gate of the Panama Canal?

There are many possibilities

 

[Hood]

Why would the USN and RN need additional ships?
Most of the IJN was already sitting on the bottom by August 1945 and Japan had no hope of completing any of the warships then on the stocks, nor of filling their bunkers with fuel.
Even a few months of Kamikaze swarms would have seriously depleted their remaining aircraft stocks to little avail.

 

[EwenS]

Many aspects raised so far to unbutton. Lets atart with the Soviets. Bottom line is that the Soviets are going to declare war on Japan by mid-Aug at the latest.

At the Yalta Conference 4-11 Feb 1945, FDR secured an agreement from Stalin for the USSR to enter the war against Japan 3 months after the end of the war in Europe.

Soviet planning for that began immediately after the Conference. The first steps were undertaken in the Far East almost immediately by starting the upgrade of both air and armoured forces already there. In April they began upgrading all the major rail lines and roads to and from and within the Far Eastern regions to assist the deployment of forces to and within the region.

On 5th April 1945 the USSR renounced its Neutrality Pact with Japan, meaning that it would not automatically renew in April 1946.

Germany surrendered on 8th May 1945. Movement of forces to the Far East began even before the German surrender with the first wave of transfers completed by the end of May with more following through the rest of the summer. David Glantz in "The Soviet Strategic Offensive In Manchuria, 1945 'August Storm'" has tables in the first chapter setting out details of the movements. To give an idea of the size of the movements these are the monthly figures May to July and the first 8 days of Aug:-

Personnel - 33,456 / 152,408 / 206,042 / 11,449
Guns & mortars - 504 / 2,624 / 3,723 / 286
Tanks & SPG - 156 / 564 / 1,229 / 170
Cargo vehicles - 1,059 / 4,475 / 10,424 / 1,416
Horses - 4,983 / 18,533 / 12,764 / 0

63% of that was moved by rail. The bulk of the force movements were complete by 25th July 1945.

But it needs to be remembered that the above was in addition to the reinforcement efforts that had been ongoing since 1941.

Soviet planning was geared towards an invasion in mid-Aug 1945. The dropping of the first A bomb on Hiroshima on 6th Aug caused Stalin to bring the invasion date forward by a few days. So at 2300 Moscow time on 8th Aug Molotov issued the Declaration of War to the Japanese ambassador in Moscow and just over an hour later the tanks started rolling across the border. While they brought overwhelming force to the main battlefront there were instances where things did not go according to plan. The Japanese defended some of the Kurile Islands stoutly, even repulsing some of the Soviet amphibious operations, but in part that was down to a lack of Soviet expertise.

As for the Kwantung Army, in 1945 it was a shadow of its former self. Many of its experienced troops had been withdrawn to fight elsewhere in China or the Pacific and the replacements were of poorer quality. And it lacked the armour to challenge the Soviet onslaught in any meaningful way.

And then we have Project Hula. Agreement for this was settled at Yalta and the organisation and planning for it kicked off immediately thereafter. The first of these Soviet manned vessels departed Dutch Harbor for the USSR on 28th May. The earlier transfers were able to participate in some of the Soviet amphibious operations in Aug / Sept.
https://en.wikipedia.org/wiki/Project_Hula

 

[EwenS]

US warship cancellations.

The US began cancelling warships in March 1945 because it already forsaw that it had plenty in service or already under construction to see it through to the end of WW2 and beyond. Losses had not been so high as expected.

The Midways had always been controversial ships, both within the USN and with FDR. He only reluctantly agreed to construction of an initial pair on 29 Dec 1942 and then a third on 26 May 1943, by which time the USN had cancelled the fourth in Jan 1943. The final pair CVB-56 & 57 were to have been part of a 1945 shipbuilding programme, the only part of which FDR approved in March 1943 related to the CVE. Cancellation in March 1945 was inevitable as even if they had been laid down in 1945 it would have been well into 1947 before they appeared in the fleet.

In asking the question about building more carriers starting in 1945 it is worth looking at the expected build up in the Pacific from mid-1945 to the end of 1946 (see JCS 1455 dated 9 Aug 1945):-

CVB - Midway & FDR by the end of 1945 & Coral Sea in Oct 1946
CV - Enterprise + 15 Essex class in June 1945 rising to Enterprise & 26 Essex by Jan 1947
CVL - 8 Independence class joined by the two Saipans in March & May 1946
CVE - rising from 54 in June 1945 to 92 in Nov 1946 (combat equipped 27 to 65)

Ranger & Saratoga were relegated to training carriers mid-1945. No account taken of losses. The Essex programme would have seen completion of Oriskany, Reprisal & Iwo Jima all left incomplete by the end of WW2. Again any further construction isn't going to reach the fleet until 1947.

By mid-1945 the Essex class was seen as inadequate for the task and steps began on the design of the new 1945 Fleet Carrier.

When CVB-56 & 57 and CV-50 to 55 were cancelled in March 1945, the USA was still fighting to clear the Philippines, Iwo Jima, Okinawa & Borneo were all still to be invaded and the effects of the kamikaze menace was already being felt in a major way. Yet they still felt comfortable cancelling them.

Just how many carriers does the USN need to maintain pressure on Japan after mid-1945 when it already has land bases on Iwo Jima & Okinawa and with Operation Olympic planned for 1 Nov that would have given them bases on Kyushu and Coronet planned for 1 March 1946

 

[EwenS]

RN construction

The Malta class were never going to be constructed IMHO. The 1943 enlarged Audacious armoured carrier design had been rejected for a 1944/45 open hangar unarmoured flight deck design that was never approved as pointed out by DWG above. But in mid-1945 there is evidence that a new Fifth Sea Lord favoured an armoured flight deck and with news of the damage arising from kamikaze hits on RN carriers off Okinawa reaching home, a rethink was certainly on the cards (see Stanley Goodall's Diaries)

Even in spring 1944, before any design had been finalised, none of the Maltas were expected to complete before spring 1948. A 1942 Admiralty study estimated 46 months to build a fleet carrier in Britain in wartime. Wartime Britain is not the USA.

Even completion of the Audacious class, expected in 1942 to complete from March 1946, were being delayed into 1947 / 48 by spring 1945.

Illustrious would also rejoin the BPF in late 1945 / early 1946 after the refit that she began at the end of June 1945 (planned for 4 months but ?)

As for the light carriers, the Admiralty expectation in spring 1945 was that the 14 Colossus / Majestic class would have completed by mid-1946, although this does seem a bit optimistic (the other pair became aircraft maintenance ships completed Feb & Oct 1945). If the wartime build pace had been maintained, maybe by the end of 1946. The first 3 were expected to begin operations in the East China Sea against targets on the Chinese coast by the end of Aug 1945 to be joined by the fourth a bit later. So maybe 1946 might have seen a third carrier squadron join the BPF. Most of the squadrons for another four air groups were almost all formed before the end of WW2.

In March 1945 Vanguard was expected to complete by the end of 1945 - maybe. But in the autumn of 1945 they were still fitting her main armament with the secondaries still to be fitted, and she then suffered some damage from an internal explosion in Sept, so unlikely. In the end she didn't commission and leave the yard until May 1946 and it was August before she was completed. Allowing for work up etc she is an unlikely candidate for the Pacific in 1946.

The first two MInotaurs, Swiftsure & Ontario were with the BPF in Aug 1945 and Superb would have followed in 1946. But none of the other ships under construction would realistically have been reached the BPF in 1946 given their state of completion in Aug 1945. However there were other cruisers in refit that would have been able to join by the time of Operation Olympic or later in 1946. Uganda (under refit in Canada in Aug 1945), Glasgow, Jamaica (latter pair left Britain in late Aug 1945 and were diverted to the EIF instead), Liverpool, Sheffield, Birmingham & Mauritius also come to mind as refits completed.

As for destroyers, 5 Battles by Operation Olympic with Finisterre by the end of the year and maybe another 4 in 1946. Main problem with the second flotilla is the availibility of the STAAG 40mm mounts to replace the Hazemeyers. Some of these ships were completing in 1946 without these mounts planned for them (eg Cadiz, Gabbard, St James). Ch/Co/Cr classes had also begun to complete from June 1945. Possibly fewer cancellations of the 1943 Battles on 15 Oct 1945.

We do know that the Ca class were allocated to the BPF and would appear as refits completed (the first pair were in the IO en route Australia in Aug 1945). Also 12 Hunt class (first two en route in the IO in Aug 1945), the RCN Algonquin and numerous Black Swan class sloops and Bay class frigates & about 40 Canadian River class frigates. The RCN would probably have contributed another 5 destroyers as refits completed (4 Tribals and Sioux)

 

[Dilandu]

The Japanese defended some of the Kurile Islands stoutly, even repulsing some of the Soviet amphibious operations, but in part that was down to a lack of Soviet expertise.

Repulsing - no. Hampering - yes, due to lack of experience & gunnery support from Soviet side. On the other hand, Japanese also acted rather clumsy, demonstrating total lack of modern warfare understanding. At Sumshu island, Japanese 11th tank regiment tried to counterattack Soviet landing troops (which at that moment lacked anti-tank cannons, since ship with them was sunk by Japanese coastal guns). But Japanese tanks lost a lot of time just wandering aimlessly around the island, and when they finally managed to find the opponent - Soviet marines already entrenched and prepared about 200 anti-tank rifles. Japanese tanks attacked on narrow road (their commander apparently did not understood the role of terrain), without infantry support, and were easily destroyed by Soviet troopers, which prepared dugouts on the road sides and hit Japanese tanks flanks. The Japanese tanks suffered heavy losses and retreated in panick-like disorder (all reigment commanders died in that clumsy attack).

 

[DWG]

The Malta class were never going to be constructed IMHO. The 1943 enlarged Audacious armoured carrier design had been rejected for a 1944/45 open hangar unarmoured flight deck design that was never approved as pointed out by DWG above. But in mid-1945 there is evidence that a new Fifth Sea Lord favoured an armoured flight deck and with news of the damage arising from kamikaze hits on RN carriers off Okinawa reaching home, a rethink was certainly on the cards (see Stanley Goodall's Diaries)

I think the only viable route to getting the Maltas operable during WWII, and even then only in 1946/1947, is for the Admiralty to stick with the initial armoured flight deck design in October 1943 and not order a rethink to open hangar in mid-1944. Obviously that requires an earlier Point of Departure.

 

[EwenS]

I think the only viable route to getting the Maltas operable during WWII, and even then only in 1946/1947, is for the Admiralty to stick with the initial armoured flight deck design in October 1943 and not order a rethink to open hangar in mid-1944. Obviously that requires an earlier Point of Departure.

Even then it is impossible.

While orders were placed in July 1943 these were no more than placeholders for the required slips. The yards can't begin to do anything until they get the requisite plans.

Design C, one of the armoured carrier designs prepared, was approved by the Fifth Sea Lord and others on 3 Sept 1943 and the Future Building Committee on the 6th and finally the Board of Admiralty on 8th October 1943. At that point the DNC began to develop a detailed design. (see Friedman).

So some months have to pass for that to happen. Friedman has a comment that the DNC had to tell Vickers Armstrong Tyne (contracted builder for Gibraltar) on 27th April 1944 to suspend all orders for materials because of the proposed review of the requirement which took place on 15th May. At the beginning of 1944 the plans were for two Maltas to be built and two suspended (Gibraltar & Africa).

Malta at John Brown couldn't be laid down until late 1944. That yard only had one slip capable of taking a Design C sized ship with a waterline length of 900ft. While it appears to have been vacant from the launch of Indefatigable in Dec 1942, a late 1944 date happens to coincide with the launch of Vanguard on the 30 Nov 1944. Behind destroyers, Vanguard was the biggest consumer of labour in 1944. That would then result in a lot of labour becoming available to begin on the steelwork of the new project.

New Zealand was the other ship that was to go ahead. At that point at Cammell Laird but transferred to Harland & Wolff on 22 July 1944. But it was not expected that she could be laid down until about April 1945 after the launch of Audacious ( later renamed Eagle). At the end of the day Audacious wasn't launched until March 1946 due to ever changing priorities.

So the yards do not seem to have been in a position to lay down a Design C in 1943 for multiple reasons. Then build in a 4 year build time and the first ship is not going to be available until 1948. Or there needs to be a major rethink of priorities in early 1944.

Such is the state of British shipbuilding in WW2

 

[Scott Kenny]

What if the Hiroshima bomb had not exploded, being captured by the Japanese?

That was the Little Boy weapon, which is the most likely design to work. A design the scientists were so sure would work that they didn't even bother to test it.

But okay, let's say it was a total dud, and lawn-darts into the concrete without going boom.

Japan would see a really funny bomb that didn't go off at first. I think they'd recognize what it was supposed to be, and it would give them enough fissionables to make one bomb of their own. IIRC they still didn't have the production capacity to make more.

What if the typhoon of 1946 had destroyed the invasion fleet of Operation Olympic?

Highly likely, that was a nasty Typhoon.

So Japan would live a little longer.

What if the U-Boats had dropped Reichenberg manned bombs on Washington?

Not a thing. None of the critical decisions were being made there.

What if the IJN's aircraft carrier submarines had destroyed the Atlantic gate of the Panama Canal?

Would have needed to happen in about 1942 to be particularly effective.

 

[EwenS]

Highly likely, that was a nasty Typhoon.

So Japan would live a little longer.

To really understand the potential weather effects on both the planned invasions of Japan, you need to turn the clock back to Sept 1945. Typhoon season in the North West Pacific region is generally between June & Dec each year and 1945 was a particularly active year.
https://en.wikipedia.org/wiki/1945_Pacific_typhoon_season
In late Aug a number of typhoons swept through the area between the Philippines and Japan, one effect of which was to delay the occupation of Japan and the formal surrender in Tokyo Bay. Then in Sept Okinawa was hit by Typhoon Ida to be followed by the more serious Typhoon Louise in early Oct. The latter while costly would have been all the more so if Olympic had gone ahead.

"However, in early October, Typhoon Louise took a sudden unexpected turn and on 9 October 1945 hit Okinawa full force, with hundreds of U.S. ships and vessels in Buckner Bay that didn’t have time to escape to sea. Twelve ships and craft were sunk, 222 were grounded, and another 32 severely damaged beyond repair. Casualties included 36 killed, 47 missing, and over 100 with serious injuries. Three destroyer-minesweepers and a destroyer escort were driven aground. The destroyer escort, Oberender (DE-444), was refloated, but the three destroyer-minesweepers were deemed not worth repair. About 107 amphibious craft were grounded, many of them wrecked beyond salvage, including four of six LSTs that were driven aground. Eighty percent of the buildings on Okinawa were destroyed or severely damaged, many still packed with war supplies. All 60 aircraft on Okinawa airfields were damaged. Only a month earlier, hundreds of aircraft were crammed on Okinawa airfields as well as many more ships and amphibious craft. The toll would have been far higher had Operation Olympic been underway. Instead, the vast majority of ships and aircraft were gone. Estimates shortly after the typhoon concluded that Operation Olympic would have been delayed by 45 days, which then would have put it in the teeth of winter storm season (in planning for Olympic, 1 December had been assessed as the last feasible date for the operation)."
https://www.history.navy.mil/about-...ectors-corner/h-grams/h-gram-057/h-057-1.html
So Olympic then has to be pushed back. The question then is how far? The knock on effect from the US perspective is then to delay Coronet. Coronet cannot go ahead without the air cover from the airfields that needed to be built in southern Kyushu on ground captured in Olympic.

And then we have TYphoon Barbara at the end of March 1946 that struck the Philippines. Based there would have been a significant part of the trrops and landing craft for a potentially delayed Coronet. D M Giangreco in "Hell to Pay put it this way:-

"Barbara would have been the closest-watched weather cell in history. If the delayed invasion of Honshu was not already in the process of being launched, the typhoon's long, lumbering approach to the Philippines would allow First and Eighth Army soldiers (many of whom had lived in tents instead of barracks because it was expected that they would have moved north a month earlier) to make the best preparations they could under the circumstances.Ships and craft that could not be sent south would be secured and likely ride out the storm with minmal losses. However, if Coronet was in the midst of its execution from the twenty-five day window Y-15 to Y+10, chaos would ensue because the storm's track and intensity could only be guessed at within the parameters of the limited data available.......

Whatever stage of deployment U.S. forces were in during those first few days of April, a delay of some sort - certainly no less than than a week and perhaps much more - was going to occur..."


And then there is another potential problem. The Soviets. They continued their advances on southern Sakhalin and in the Kuriles right through to 2nd Sept 1945. They had some plans to make amphibious landings on the most northerly of the Home Islands, Hokkaido, but in Aug 1945 lacked the capabilities to do so, or at least the capabilities to do so in sufficient numbers to overwhelm the defenders. But give them another 6-8 months and what happpens? The USA was resolute in not wanting to involve the USSR in the occupation of Japan. But what happens if the delays to Olympic & Coronet give them time to build strength and gain a toehold?

 

[Dilandu]

And then there is another potential problem. The Soviets. They continued their advances on southern Sakhalin and in the Kuriles right through to 2nd Sept 1945. They had some plans to make amphibious landings on the most northerly of the Home Islands, Hokkaido, but in Aug 1945 lacked the capabilities to do so, or at least the capabilities to do so in sufficient numbers to overwhelm the defenders. But give them another 6-8 months and what happpens? The USA was resolute in not wanting to involve the USSR in the occupation of Japan. But what happens if the delays to Olympic & Coronet give them time to build strength and gain a toehold?

Well, it would be pretty clumsy from political - both internal and external - if Truman would start to demand that Soviet must not invade Hokkaido. The American population would be quite puzzled why Truman preferred more Americans to die in already-won war, instead of accepting Soviet help.

On the other hand, Stalin never was actually interested in Japan. He understood perfectly well, that at most he could get Hokkaido - which wasn't particularly important, and would be pretty costly to control due to logistic issues.

So most likely outcome would be, that USA and USSR would make an agreement: the Japan would be fully American sphere of influence after war, and Korea would be fully Soviet. Soviet troops would move on Hokkaido (likely would even get some US support to get there) but would retreat from island in six month after Japanese surrender.

 

[T. A. Gardner]

With regard to the Soviets: They weren't going to invade Hokkaido. The US had given them a good number of landing craft for amphibious assaults (sailed from Alaska in some cases). The invasion of Shumshu in the Kurile Islands showed as much. The Soviets lost a fair number of the landing craft involved, and their casualties getting ashore were atrocious. The best they could have likely done in 1946 is take Sakhalin Island and the Kuriles with what they had. Their focus would have been on taking ground in China and Korea with an eye to keeping it.

If the US didn't want the Soviets to do amphibious operations, they wouldn't have given them the landing craft to do them. By 1946, the Soviets would have had sufficient landing craft to put about a reinforced infantry division ashore in one go. The Soviets more likely would have landed reinforced regiments from several divisions with the intent of building them up to full divisions in successive waves. This would have taken them anywhere from a week to weeks to do. At Shumshu, each wave sailed about 150 NM, was delivered, then the surviving landing craft went for another load. This would have been what they would have had to do in a Hokkaido landing.

As for the US, nuking and firebombing cities would have continued along with a mining program that would have ended virtually all shipping, coastal or intercoastal, meaning all imported resources and even troop transfers would have ended. Coastal bombardment by USN and even RN vessels would have become more common along with naval airstrikes.

If the US wanted, they could also have taken offshore islands to set up launch positions for V-1 (JB-2 / Loon) and V-2 clones and started pummeling Japan with those. Even air launched JB-2 could have been used.

The US build up for an invasion would have continued at a rapid pace as Japan crumbled into ruin.