"What would an Invasion of Japan in 1945 Look Like?" Topic

"August of 1945 heralded the beginning of a new era in warfare, the introduction of the atomic bomb. The strikes against Hiroshima and Nagasaki, while it was hoped they would cause Japan to surrender to surrender and end the war, the expectation was that they would continue to fight. America had already begun planning for an invasion of Japan with upwards of 5,000,000 American and 1,000,000 United Kingdom forces taking part, starting in November of 1945.

The plan was codenamed Operation Downfall with two sub operations, Operation Olympic and Operation Coronet taking place in November 1945 and March of 1946 respectively. Planners were unaware of the existence of the Manhattan Project so their considerations did not take into account atomic weapons or their usage.

Operation Olympic called for an invasion of the Japanese island of Kyūshū with air support coming from the recently captured island of Okinawa. The projected strength of the invasion force was to be over 800,000 personnel and almost 135,000 vehicles spread across 11 infantry divisions and 3 marine divisions. This force would secure the island of Kyūshū and suitable land for airbases which would support the following invasion of Honshu, where Tokyo was located. The goal was not to take over the entire island but merely to have enough staging to continue with Operation Coronet…"

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Armand

A blood bath on both sides. Glad it didn't have to happen.

Indeed. Casualty estimates were 500,000 Allied and at least the same number of Japanese. As horrible as the use of atomic weapons was, it's not hard to understand why they were.

I wonder if it would have been needed. I've read that the next, never-completed phase of the Allied air offensive against Japan was a shift to the railroads, which was never completed (although it was sufficiently advanced that the railroad roundhouse in Kyoto would have been the designated aim point for the first atomic bomb, had Stimson not removed the city from the target list).

The argument goes that the destruction of the Japanese merchant fleet was already straining the railroads, and that a prolonged offensive would have completely overwhelmed them and broken the food supply chain, leading to famine and chaos. There is certainly a case to be made that the decision to bomb the German railroads was one of the most effective targeting choices made in the CBO in Europe, starving the German factories of supplies, and the armies of munitions.

The Navy was planning on a full blockade with in shore mines. Why invade when freezing and starvation will do the job. You can't divine wind with out gas.

I agree. The Japanese were on the verge of having nothing left to fight with logistically. Including trained soldiers. No navy or Air Force to speak of. Fanatic guerrilla tactics maybe, but they were also worn out.I doubt they could have conducted large scale military operations to oppose the invasion by the time we were through bombing, shelling, and blockading pre-invasion.

In addition, the Soviet Union declared war on Japan on 9th August. They had over 1.5 million troops and had defeated the Japanese forces in Manchuria.

Whether the defeat of Japan was ultimately brought about by an allied invasion or by starving the Japanese out through a blockage, one thing is for sure: many more Japanese would have died than died as a result of the two A bombs that ended the war. Starving millions of Japanese to death would not have been more humane than the use of nuclear weapons.

Plus remember it wasn't just the Japanese home islands. The Japanese had large forces remaining in other parts of Asia who would have continued the fight so long as the fanatics in Tokyo remained in charge.

There were a number of Japanese leaders that argued the Japan should fight until nothing was left as a way to honor the emperor and save their honor. Losing the railroad lines would not have changed that attitude. Even after the dropping of the first atomic bomb there was an attempt coup by officers who wanted to keep fighting. I have never agreed with this "we never had the drop the bombs" argument.

My Dad was USMC and scheduled to be ashore 6 hrs before initial shelling for landing. He was sniper/scout & had a 17minute life expectance after his first shot. I would not have been here or either of my 2 brothers, so nuclear weapon use saved my life.

Those nuclear weapons saved countless POWs on the Japanese mainland, not to mention the local civilians (way from ground zero of course).

The miracle was the collapse of Imperial Japanese resistance within a matter of days, which saved countless lives on many sides.

I could agree the entry of the USSR into that war was almost as significant, but the main thing was to end the insanity ASAP.

The allies had the sense to slightly ease up on "Unconditional Surrender" and agree the Emperor could stay on. Heck, if it saves a half a million GIs, he could be a God, if it suits them…oh, he was, I guess.

No doubt- the use of nuclear weapons saved a lot of people- particularly Americans- who would've died as the campaign proceeded. I think it was the right thing to do, because the continuation of the war would have undoubtedly cost American lives. Paul Fussell's "Thank God for the Atom Bomb" gets that exactly right: "what do all those lives mean? Plenty, if you're one of them or related to them."

But I do wonder whether Japan could've retained the ability to resist if the food supply failed massively while the staging for the invasion proceeded.

A gent I once worked with had been a US Marine in WW2, he survived Saipan and Iwo Jima. He and his friends fully expected to die during the invasion of Japan. When he heard that some super bomb forced the Japanese to surrender, he said "God Bless Harry Truman and the Atom Bomb."

Thanks.

Armand

I reluctantly agree that the atomic bombing was the lesser of 2 evils, and probably had to be done.

A further thought is that once it had been done, and once the world saw the result, they might have been more reluctant to use them in future conflicts. So far anyway that has been the case.

Similar case to that of zulupaul. My uncle was aboard ship
headed to Japan when the surrender happened. His regimental
commander had prior told all the men to look at the man to their left and then to the man on the right. He quietly said
that one of them would likely not survive. Thankfully, the
bomb probably saved his life as well as that of my father
and many other family members. It was a necessary decision
and the right one.

Don't forget that the Purple Hearts awarded today were minted
during WWII in anticipation of casualties lost during an
invasion of Japan. There were 500,000 medals remaining after
the war's end.

Much shorter and less bloody than feared. Japan was exhausted and lacking every resource needed to mount any coherent resistance.

It's one thing to defend an island to the last man and give no thought to the civilians when you don't consider them fully human. Another thing to expose your native land and civilian population to such slaughter.

I strongly suspect as soon as allied forces had a firm foothold on the main home islands the same thing as happened after the atomic bombings would have happened. Of course, we cannot prove this either way.

Much of the hype about how horrific the invasion would have been is to justify the A-bombs.

I get why they dropped them and do not consider them much worse than the 'conventional' fire bombings.

I suspect no more than 100 000 casualties on the allied side and maybe 2-300 000 Japanese.

Bottom line … the US [and the allies] after fighting the IJFs on islands like Saipan, Okinawa, Iwo, etc. Demonstrated that the IJFs were going to fight to the death and cost the US high losses. So that strongly influenced the dropping of the A-bombs on Japan. Also note the US and Western allies were pretty war weary too. Units from the ETO were planning on going to the PTO.

If the war had a chance to be ended quickly … and save US/Allies lives, we had to go for it. Would anyone with any commonsense risk thinking the IJFs and even Japan's population would not fight to the death ? And in doing that inflicting heavy losses on the US/allies.

In reality the US dropping the A-bombs on Japan in the long run saved lives on all sides. I know some don't get that … but it is a fact.

Counterfactuals are inherently unknowable, but one thing we do know is that the Japanese deduced MacArthur's plan, and managed to double the troop strength on Kyushu between the end of the battle of Okinawa and the dropping of the bomb on Hiroshima. That would not have made the invasion any easier- although one thing that should be noted is that the casualty disparities between Japan and the Allies got progressively more lopsided (in the Allies' favor) as the war proceeded. I think by Okinawa it was in the 10:1 region, IIRC.

But the real point is not, I think, to total up the combined Japanese and American dead for two alternative courses of action, and then to advocate for whichever one seems lower. That's not how decisions like this get made. No commander in that war or any other was saying, "gosh, how can we minimize the number of enemy dead?" They chose the course of action that would kill the most of the enemy and the least of their own side, and bring them most quickly toward the ultimate goal of a victorious end to the war. The atomic bombs looked like they might do that- and so the US dropped them without hesitation (and they even rushed Nagasaki, to get it in before a spell of bad weather that might potentially have lengthened the war a couple of weeks).

Okinawa was considered a home island with Japanese civilians and look at the resistance there. People even jumping off cliffs to their death. I highly doubt it would have been much different if the US landed on other Japanese home islands. I think the estimates of US losses are justified.

Okinawans were not considered truly Japanese though and still aren't today by many Japanese.

Okinawa was full of IJFs … that was all that really counted … IIRC the Okinawans suffered greatly regardless.

Grandpa was a Seabee at Guadalcanal, Vela Lavella, Bougainville and Okinawa. He was seriously wounded at Vela Lavella and told he could go home. After being patched up on a hospital ship he chose to return to duty and ultimately served until 1946. He never talked much about his time in the war but I distinctly remember him saying he didn't regret his decision to return to duty until he got to Okinawa. He said they would have got him for sure if they had invaded the Japanese home islands. Seabees were always a high priority target.

The justification for the use of nuclear bombs on Japan is predicated on the explicitly racist myth that Japanese policy makers and the populace at large were a mindless herd of religious fanatics entirely divorced from the reality of their defeat and ready to die on a moment's notice for the mere opportunity to take an American or Western life with them.

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According to the way America (as a culture) likes to write history, the US is utterly incapable of being the bad guy – unless absolutely necessary – and the myth described above provided this false premise of "necessary" to what would have been otherwise universally deemed an act of criminality and barbarism – the atomic bombing of civilian population centers.

The idea that the Japanese were willing to die for their country and their emperor is hardly a racist myth. I suggest you read "The Fleet at Flood Tide" by James D. Hornfischer. Its primary focus is on the campaign in the Marianas Islands and the invasion of Saipan. It was here that the Americans first encountered Japanese civilians in significant numbers and their willingness to sacrifice themselves came as a horrifying shock. First person accounts from the few survivors makes this a striking narrative.

Those that argue that a blockade would starve Japan into submission are not thinking it out. Yes, Japan needed to import food to feed everyone, but they did grow quite a lot of food on their islands and they grew it everywhere it was possible to do so. No city was too terribly far from the farms so food could have been transported without the railroads if necessary. Some people would have starved, but which ones? Not the Imperial Family or the government. Not the military, not the factory workers, and not the ones growing the food. So who? The old, the very young, and anyone not doing important work.

The Japanese military was still a formidable force. The navy was mostly gone, but the army had several million troops backed up by millions more civilian militias. And they had 10,000 planes ready for action and enough fuel for at least one suicide fight. The militarist who controlled the government were hoping that their continued resistance would wear out the Americans to the point they would agree to a negotiated peace. Without the atomic bombs, they might well have been right.

Another reason Truman used the bombs was to demonstrate to Stalin that we had them, they worked, and we were not afraid to use them.

There was not anything necessarily more immoral about the atomic bomb (based on what was known to the users at the time) than the conventional air raids against Japan (or Germany, for that matter). The devastation and casualties of the raids on Tokyo, Dresden and Hamburg (the big raids where the combination of munitions and weather generated firestorms) approached the lower end of the nuclear threshold in their own right.

And it's just silly to describe the rationale for use against Japan as specifically racist. Everything the Allies did to the Japanese, they had previously done to Germany; it was Japan's particula misfortune to come under aerial attack after the Allies had perfected their techniques, tactics and procedures by bombing Germany. The only reason the atomic bombs weren't dropped on Berlin and Munich was because the armies got there before they were ready. Truman's rationale was simple and clear: they did it to end the war.

Yes, you are right. Okinawa, Iwo Jima, Tarawa are all racist myths of Japanese soldiers fighting fanatically to the death. Never happened. Japan would have meekly surrendered once you got to the main Japanese islands. Right.

Scott, Nine Pound, Grattan +1 …

Some others may want to look up the definition of "revisionist history" … Too many try to put today's standards, morals, etc. on what happened decades or more in the past.

Ask the POWs about the A bombs and the miracle of the sudden collapse of Japanese resistance to the Allies. How many would have made it in a conventional attack on the mainland?

Again, some still don't get that …

I really think the best defense of the decision was put by Paul Fussell in his essay, "Thank God For The Atom Bomb," and also in places in "Wartime:" Americans were dying by the thousands every day that the war went on.

The government's principal obligation was to bring that war to a successful end as quickly as it could. Yes, aerial bombing is ghastly, but both the Allies and the Axis had passed that moral threshold years ago, and there was no going back. Six months would have meant a heck of a lot of American casualties, and no responsible government – particularly a democratically elected one – would reject the means of ending it immediately if they were available. The atomic bomb was that means: it took two of them, but the second one convinced the Japanese government that Truman's "rain of destruction from the air" was not an idle threat.

None of the Axis powers were led on a strictly rational basis; the control of information made it hard for the population to fathom the degree of defeat their nations faced until their cities were collapsing in ruins. That came first to Germany; it took a long time for the air war to reach Japan, so it's perhaps less surprising that there was still a substantial will to resist in 1945. But the great merit of the atomic bomb was that it simultaneously combined the successful Allied strategy (military effectiveness) with the unsuccessful German strategy (spectacle) to create a psychological effect on the nation's leaders that wasn't otherwise attainable.

+ 1 Nine pound !

Not one Japanese military unit surrendered to the Americans during the pacific war. No Japanese government had surrendered to a foreign power in Japan's history—by Japanese count a span of 2,600 years.

Besides the three and a half million troops in the home Islands there were over three million on the Asian mainland and on smaller islands throughout the Pacific.

By July 1945 the US had only fought a fraction of the Japanese ground forces. Given the tenacity of Japanese resistance so far, can you imagine the same resistance on the Asian mainland? It would have taken years to defeat them. No wonder Truman needed the Soviets to invade China. Fighting in the Philippines continued to the end of the war.

In June (I think it was the 15th) the JCS meet with Truman to discuss Operation Downfall. They were asked beforehand to bring estimated casualties figures.

Since the Army represented by Marshall was, at the time, for the invasion they lowball (for lack of a better term) the numbers. The Navy, Adm. King did not bother to come up with a number they just knew it was unacceptable. The Navy wanted to stick to pre-war plans of blockading and bombardment. King never agreed to the invasion. He agreed that preparations were to be made just in case.

When Marshall started to see intelligence that the Japanese had greatly increased the number of troops on Kyushu. He suggested to General MacArthur to alter the invasion plan. Mac refused.

Japanese farmers had two failed crops in a row. To blockade the island would have resulted in millions of Japanese civilian deaths due to starvation and disease. The American public were showing signs of war weariness and some called for a negotiated peace. So what was the alternative?

The war weariness was demonstrated by the few public opinion polls at the time. There were calls in Congress to reduce war manufacturing by half. The points system which was the system to bring troops home from Europe and mustering out the most experience soldiers and airman was proving a disaster.

Families began lobbying their Senators and Representatives if they could help in keeping their love ones out of going to the pacific.

This is exactly what the Japanese were counting on. The Japanese were not stupid this was part of a planned out and calculated strategy to force a negotiated peace.

The time it would take for the Navy blockade and bombardment plan to work, played right into the hands of the Japanese leadership. As they had shown little care to the plight of their own civilian population. Ask yourself what the Japanese would have done if they had an atomic bomb?

I recommend Richard Frank's book.

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+2 Old Contemptable …

Big +1 Old Contemptible re Frank's book "Downfall".

A close read reveals that the 500,000 Allied casualty figure was a preliminary best guesstimate; no one really knew with confidence what the ultimate price might be.

B

I am assuming (an error) that you all will try to translate this alternative history into a so called historical miniatures simulation/game.
Yes?!
Well, maybe No?!
A boardgame, yes, a miniatures game (after all, this is a miniatures site) No.
If you do attempt this, well, there would be at least two problems. 1. Only Japanese aviation figures would be shown as the IJN was gone, totaled, and the Japanese land forces hidden underground following the practise at Iwo and Okinawa, thus no IJN figures and almost no IJA figures
2. A mountain of Allied figures. This invasion would be several times larger than the cross Channel D Day
8 to 10,000 ships and 5 to 7,000 planes (possibly with Allied jets on redesigned CVs) and of course, probably 250,000 troops And nuclear weapons.

Of course you could use the miniatures as place settings like in Axis and Allies--but that game is a boardgame, not miniatures.

SPI made a war game back in the 70s(?) about this invasion. "Operation Olympic". Played it a number of times, have in my Map Room somewhere. If that game was at all accurate … the US loses would be very, very high. And the Japanese as well …

Operation Olympic : link

@ Old Contemptible

Besides the three and a half million troops in the home Islands there were over three million on the Asian mainland and on smaller islands throughout the Pacific.

This. Always overlooked. Defeating the Japanese in the home islands did not amount to defeating Japan.

The island-hopping campaign defeated about a quarter of the IJA, the Burma campaign about another quarter. The remaining half of the IJA had yet to be defeated at all, and it held hundreds of thousands of Allied prisoners.

The calculation was, rightly, how many Allied lives will the Bomb save. It's not a military priority to spare enemy lives.

The calculation was, rightly, how many Allied lives will the Bomb save. It's not a military priority to spare enemy lives.

Some still don't get that …

It's not a priority to consider how many enemy would die.
It's somewhere there in the list though.
There was a nuclear bomb powered craft design considered during the cold war. That thing would have left a swathe of devestation in it's path.
The project seemed viable but was shelved as being beyond the pale.
Consequences too horrible.

We are writing about miniatures, not boardgames--or have I missed the title and subject of this site?

The size of the entire invasion of Japan in minis would be enormous, I'd think. And probably in 6mm. Fighting a smaller portion of the invasion of course could be done with 6mm or 25/28mm. E.g. like gaming a portion of a Normandy beach, or specific battle. E.g. Brecourt Manor …

If you want to get the scope of the Invasion of Japan and losses a boardgame is much better. As I posted about SPI's "Operation Olympic" …

How many minis would it take to game Bn, Rgt, or Bde ? Many, as I have done those levels before with 6mm. But IMO Bn or Co level is best for minis.

Is much known about Japanese homeland beach defences? Was it Iwo or Okinawa on the corresponding scale?

The Japanese Homeland beach defenses were not the West Wall. But they still would be challenging. Plus as we saw, they may retreat away from the beaches and fight inland in prepared positions.

Regardless, high loses would be taken by the US/Allies. To avoid this there was even a plan to use chemical weapons to attrite the Japanese Forces, etc.