Japan Fights On After Nagasaki: Or, What Do You Do With Your Nukes?

[Athelstane]

So many atomic bomb threads this week, so little time...

Today of course is the 75th anniversary of the atomic bombing of Nagasaki, the second (and so far, last) city to suffer destruction from nuclear attack. I think most people here appreciate that the United States was fully prepared to keep splitting atoms over Japan if a surrender wasn't forthcoming. As Harry Truman said on August 10, "We shall continue to use it, until we have destroyed Japan's power to make war. Only a Japanse surrender will stop us." To that end, Prof. Mark Felton has yet another new video up today on Youtube about what likely would have happened next.

Gen. Leslie Groves informed the JCS that his team on Tinian would have a third bomb ready to use on August 19. And he still had cities left on the July 25 order from the War Department (Document 13 above): Kokura and Niigata. Of course, given Truman's decision to pause atomic bombing after Nagasaki, there is no guarantee that this list would not be expanded, or that a different specific city would not be given to Spaatz and Groves to target. Felton surmises that Kokura would draw the short straw, with Niigata being the backup target. Seems plausible to me, too.

After that, however, things remain more uncertain. Operation MAJESTIC - the massive amphibious invasion of southern Kyushu scheduled for Nov. 1, 1945 as X-Day, previously called OLYMPIC until the name was compromised after being sent out in unsecured code - planning was still in full swing, and atomic bombs could be enormously useful in smashing Japanese defenses. And there would be only so many bombs to go around. For the record, the planned production rate was for 3 bombs per month starting in August, which was expected to rise to 5 bombs per month in November, and 7 bombs per month in December. In 1946, it could rise much higher. This could mean as many as 6 bombs for use, all at once, on or right before X-Day - but only if the attacks on cities ceased for the time being, which of course poses its own difficulty in terms of Allied messaging to Tokyo. ("The Americans were bluffing! They only had a few bombs after all!")

[This raises the question of the massive October 1945 typhoon, and the risk that it could have delayed MAJESTIC all the way to spring, though there remains some dispute (@Matt Wiser did some study on MAJESTIC in this regard) about the delay it could impose. But American planners in August don't know about that yet.]

So, assuming that Japan continues to fight, presumably because the attempted Kyūjō coup actually succeeds, or the Emperor decides to intervene on the side of the hardliners, in hopes of obtaining "honorable" terms from the Allies:

1. What would U.S. leadership (President Truman and his chief advisors) most likely have decided to do with its atomic bombs going forward?
   1. Continue a regular tempo of bombing Japanese cities (and other high value targets) going forward, as bombs became available?
   2. Call a halt to bombing to build up a small stockpile of bombs to be used in support of Operation MAJESTIC?
   3. Proceed with some mixture of (1) and (2)?
2. If the United States proceeds with non-invasion related bombing, what cities and other targets would be on the expanded target list? Would Tokyo and Kyoto continue to remain off the list?

As a corollary I would be curious what people think would be the most likely course of action for November onward if in fact MAJESTIC is called off until March, replaced with CORONET, or even scrubbed altogether for Nimitz's and King's preferred strategy of bomb-and-blockade. There are all sorts of possibilities here, and a growing stockpile of nukes to do them with. Obviously, there are people who think that Japan would have been forced to surrender by that point anyway...

 

[Matt Wiser]

Tokyo was off the list because it had been razed to the ground already; and you need someone in Tokyo alive to sign the surrender papers when that comes about. Kyoto was also off at Stimson's direction, and I doubt he would've acceded to Groves' requests (which likely would have continued,) and Truman supported his decision.

Continued nuclear strikes are very likely. Kokura and Niigata would have been struck in turn, while a search was made to select additional targets. The problem was that the conventional bombing campaign was running out of targets, The 20th Air Force and the newly-arrived Eighth would've been out of major targets by October. Which means the B-29s would have to support the preinvasion bombing effort in Kyushu.

When Truman approved OLYMPIC on 18 June, he added a proviso: one final consultation prior to executing the invasion. There would either have been a JCS meeting with the President and both Stimson and Forrestal (SECNAV) attending, or, as is likely, a meeting in Hawaii with Truman, Leahy (Chair, JCS), and possibly Marshall, and both Admiral Nimitz and General MacArthur. It would be at that meeting that the final decision to launch the invasion of Kyushu would have been taken.

Could the bombs have been used to support the invasion directly? Marshall did raise that question with General Groves, and Groves asked Oppenheimer if Fat Man could be used in a tactical role. Oppenheimer said that it was possible. By the time Marshall got his answer from Groves? It was the morning of 14 Aug Washington time, and we know what happened later in the day.

 

[TxAggie]

I think if a bomb's ready by the 19th, Kokura's getting glassed. The destruction of the arsenal there would make the Olympic folks happy as well as the bomb-and-blockade crowd, so I don't see anything that would hold that bombing up.

After that, it comes down to a matter of timing IMO. The Soviets are going to be running wild through Manchuria, and they're going to start making the US nervous with how much ground they're seizing in China and Korea. The US will probably want to press for a landing as soon as possible, and that probably means stockpiling nukes for an invasion in fall 1945. If the Olympic landings go ahead, those are getting dropped in support of the invasion on Kyushu. But if the typhoon stops them through the winter, the only way they'll have to keep the pressure on the Japanese to capitulate is through bombing, so they'll probably start using some of their stockpile on more conventional strategic-bombing targets.

Meanwhile, the onus is on the Japanese - there's no hope of them winning the war, but they're the only ones that can now end it. So when do they cave becomes the biggest question for me.

There's a common attitude on here that assumes if the Japanese don't surrender in August '45, they'll never surrender, and the Allies will literally put up body counts in the tens of millions while the Japanese just continue to pour more civilian lives into the breach without blinking. There was some TL on here where the author predicted 90% of the Japanese population would die before the war ended. With respect to that author's research, I don't buy that viewpoint. IOTL, Japan actually did surrender, so it's not like that card is totally off the table. Even if the hardliners grabbed the wheel, it's still an option floating out there. As the bombings and nukings continue and the food situation grows dire, there may come a point where even the hardliners decide to call it, or they get couped by what's left of the Japanese government and military.

If the hardliners end up dragging it out to the bitter end, I think a near-genocide of the Japanese people through military action and starvation is a very real and very grim possibility, but I don't see everyone else going along with the "victory or death" gameplan indefinitely. My guess is they fold by spring '46, invasion or not.

Anyway, as far as other targets after Hiroshima, Nagasaki and our ATL Kokura, the Army commissioned a study on the best targets for nuking and Kyoto wound up as the #1 city on their list, tied with Hiroshima. Stimson is going to fight tooth and nail to protect Kyoto, but if nukes become a regular ongoing thing and half a dozen other lower-priority cities are hit, Kyoto's just going to stand out more and more alone at the top of the list. It's going to catch a bomb eventually.

Tokyo though, I don't see it being nuked. A large part of it had already been destroyed by firebombings, so the raw destructive power of a nuke would be wasted on it, and as the saying goes, you need someone left alive to surrender to you. It might catch another conventional attack, but it won't get nuked.

 

[Athelstane]

Tokyo was off the list because it had been razed to the ground already; and you need someone in Tokyo alive to sign the surrender papers when that comes about. Kyoto was also off at Stimson's direction, and I doubt he would've acceded to Groves' requests (which likely would have continued,) and Truman supported his decision.

Continued nuclear strikes are very likely. Kokura and Niigata would have been struck in turn, while a search was made to select additional targets. The problem was that the conventional bombing campaign was running out of targets, The 20th Air Force and the newly-arrived Eighth would've been out of major targets by October. Which means the B-29s would have to support the preinvasion bombing effort in Kyushu.

When Truman approved OLYMPIC on 18 June, he added a proviso: one final consultation prior to executing the invasion. There would either have been a JCS meeting with the President and both Stimson and Forrestal (SECNAV) attending, or, as is likely, a meeting in Hawaii with Truman, Leahy (Chair, JCS), and possibly Marshall, and both Admiral Nimitz and General MacArthur. It would be at that meeting that the final decision to launch the invasion of Kyushu would have been taken.

Could the bombs have been used to support the invasion directly? Marshall did raise that question with General Groves, and Groves asked Oppenheimer if Fat Man could be used in a tactical role. Oppenheimer said that it was possible. By the time Marshall got his answer from Groves? It was the morning of 14 Aug Washington time, and we know what happened later in the day.

So, it sounds like you're projecting a combination of (1) and (2), then? Kokura and maybe another city or two get immolated, and the other bombs get reserved for X-Day?

Tokyo did keep getting struck from the list for both reasons, though, from whatI have made out, chiefly so as not to kill the emperor. One wonders if they might revise that if it became clear that Hirohito had relocated away from Tokyo to some other, more secure, location?

 

[gatordad699]

I’d think that Kokura would be next. It was the primary target on August 9. Nagasaki was the secondary target.

 

[Matt Wiser]

That's assuming, of course, that the decision is made to use the bombs in direct support of the invasion.

The intended aim point for the Kokura bomb was about 400 yards from Japan's largest CW plant (Mustard, Phosgene, etc.). At the time, it was listed as a chemical works, and not until after the war and the occupation began was it realized that the plant had a CW role.

 

[Athelstane]

There's a common attitude on here that assumes if the Japanese don't surrender in August '45, they'll never surrender, and the Allies will literally put up body counts in the tens of millions while the Japanese just continue to pour more civilian lives into the breach without blinking. There was some TL on here where the author predicted 90% of the Japanese population would die before the war ended. With respect to that author's research, I don't buy that viewpoint. IOTL, Japan actually did surrender, so it's not like that card is totally off the table. Even if the hardliners grabbed the wheel, it's still an option floating out there. As the bombings and nukings continue and the food situation grows dire, there may come a point where even the hardliners decide to call it, or they get couped by what's left of the Japanese government and military.

If the hardliners end up dragging it out to the bitter end, I think a near-genocide of the Japanese people through military action and starvation is a very real and very grim possibility, but I don't see everyone else going along with the "victory or death" gameplan indefinitely. My guess is they fold by spring '46, invasion or not.

I think @The Red 's timeline, Decisive Darkness, remains the most compelling timeline of a "Japan Fights On" scenario, even if I might quibble with details. Not least because his outcome is a more unsettling one between the extremes: The problem is that it drags on long enough, with enough destruction, that there is no longer a recognized emperor or central command authority left to surrender when the time comes. So surrenders come here and there, from different factions and commands. This was a live fear by senior Truman Administration and military leaders in 1945. You could have pockets of resistance all over Japan, East Asia and the Pacific holding out into 1947 or even later, because there's no one whose authority they recognize to tell them to lay down their arms.

I can't recall what his final body count was, but it was substantial without being overwhelming. 10-20% or something like that. Which is horrible enough by itself.

But if the typhoon stops them through the winter, the only way they'll have to keep the pressure on the Japanese to capitulate is through bombing, so they'll probably start using some of their stockpile on more conventional strategic-bombing targets.

I wouldn't disagree with this.

Whether Louise would kill MAJESTIC til spring is not something I am in a position to suss out. Matt Wiser's research aside, the Army did a study 8 months after the war which said it would have pushed it back just 2 weeks. (See below, page 255 from John Ray Skates' The Invasion of Japan: Alternative to the Bomb.) Matt says there was a 1985 Defense Department study which reached the same conclusion. I'm a bit skeptical, but I really can't say I've researched it enough. (Does anyone have daily weather results for Southern Kyushu in November 1945?) Of course, every week you push it back, the weather gets worse. It would make the English Channel feel like Walden Pond.

 

[Athelstane]

That's assuming, of course, that the decision is made to use the bombs in direct support of the invasion.

The intended aim point for the Kokura bomb was about 400 yards from Japan's largest CW plant (Mustard, Phosgene, etc.). At the time, it was listed as a chemical works, and not until after the war and the occupation began was it realized that the plant had a CW role.

That could have been a lucky stroke. Well, small luck in what would otherwise be a dystopian timeline . . .

 

[Athelstane]

That's assuming, of course, that the decision is made to use the bombs in direct support of the invasion.

Well, I mean, maybe that is something worth asking more expressly than I did. Is there good reason to believe that Marshall and MacArthur would have decided against using nukes on X-Day?

 

[Matt Wiser]

Nothing in MacArthur's material, or so I understand. Had the war gone on longer, Marshall would've asked His Majesty for an opinion on the matter.

 

[Athelstane]

Nothing in MacArthur's material, or so I understand. Had the war gone on longer, Marshall would've asked His Majesty for an opinion on the matter.

That sounds about right.

MacArthur may not have liked the Bomb, but it would awfully hard to resist using it, if there was a way to use it. Not that he would have much choice if Marshall told him it had been decided above his pay grade. If Harry was willing to glass cities, I can't imagine he would cavil at an invasion beach.

I wonder how easy it would have been to identify targets worth using the Bomb on. Invasion Beaches? There were, like, 35 of those, though, right? (See below.) Or what about Japanese troop concentrations? Could you even identify them from the air? A lot of coffee, cigarettes, brain cells, and aerial reconnaissance would have been expended trying to figure THAT out.

 

[Matt Wiser]

I Corps: Miyazaki; XI Corps at Ariake Bay, V Amphibious Corps: Kushikino (WINTON and STUTZ), and IX Corps (X+4) on PLYMOUTH and/or PACKARD.

Some of the preparations could be seen from aerial photography, and others via submarine recon. Submarine recon close-in to get pictures had become SOP by 1944. It's possible that UDT Teams would have been landed by submarine to get further information on the beaches....

 

[Athelstane]

I Corps: Miyazaki; XI Corps at Ariake Bay, V Amphibious Corps: Kushikino (WINTON and STUTZ), and IX Corps (X+4) on PLYMOUTH and/or PACKARD.

Some of the preparations could be seen from aerial photography, and others via submarine recon. Submarine recon close-in to get pictures had become SOP by 1944. It's possible that UDT Teams would have been landed by submarine to get further information on the beaches....

A real coup would be detecting a major kamikaze marshalling airfield or depot.

Even if it's one of the ones in a cave, you can pretty well seal it off with nuke, I assume.

I'm not clear on just how much the Japanese dispersed those, though. You'd need something big enough to justify expending an a-bomb.

 

[Matt Wiser]

The Japanese were dispersing their air, both Army and Navy. The big bases like Kanoya NAS and Chiran (a longtime hub of Japanese Army Aviation) were being abandoned in favor of smaller dispersal fields (there were over forty). Those fields would've attracted attention from B-29s (and Far East Air Force B-24s and B-32s) instead. Try a dozen or so B-29s with forty 500-lb. bombs on a small airfield instead of wasting a Fat Man. You'll need something like a divisional-sized base area or defense area to justify expending one or more Fat Man type weapons.

 

[Captain Homicide]

See below, page 255 from John Ray Skates' The Invasion of Japan: Alternative to the Bomb

Would you recommend this book for learning about Operation Downfall and are there other books you would recommend on this topic?

 

[Whiteshore]

There was some TL on here where the author predicted 90% of the Japanese population would die before the war ended.

Decisive Darkness? It wasn't 90% bad but it was reaching Paraguay-level bad. It didn't help that the hardliners were purging relatively moderate elements of Japanese society after they tried to surrender.

 

[Matt Wiser]

Would you recommend this book for learning about Operation Downfall and are there other books you would re commend on this topic?

I would strongly recommend this, along with Norman Polmar and Thomas Allen's Code-Name Downfall. The Reports of General MacArthur is also a valuable source, as the two volumes (one about the U.S., the other Japan) have useful information on planning and preparations for OLYMPIC, and an outline of not only CORONET, but KETSU-GO (the plan for the defense of the Home Islands). I used those works, along with primary source material, when I did my MA Thesis in 1999 on the planned invasion.

One novel worthy of mention is Lighter Than a Feather, by David Westheimer, who wrote Von Ryan's Express, which came out in 1971. It reads like a history book, detailing the planning and preparations on both sides, a Soviet offensive into Manchuria, Karafuto, and the Kuriles on 22 Aug 45, and the assassinations of two of the key figures of the peace faction in Japan-Marquis Kido, the Lord Privy Seal, and Foreign Minister Togo. The invasion is delayed by the October Typhoon, and is launched with X-Day being 12 Nov 45. After bitter fighting, Japan surrenders after losing Southern Kyushu on 14 Jan 1946. Westheimer depicts characters from both sides, and he gets both American and Japanese tactics right. Japanese units are accurately identified and correctly positioned, as are the assault and follow-up units of the U.S. Sixth Army.

Skates actually called Mr. Westheimer and congratulated him for doing a good job. I'd read Skates' book first, then the novel.

 

[Vabasion]

By April of 46 that leaves you with 45 weapons at least. I’d pursue the invasion with planed tactical use of nuclear weapons, both at the beaches as well as in major operations where Japanese units would be forced into heavy action. Armed forces would be transformed into feelers, prodding and pushing as far as they can without meeting heavy resistance. Once such resistance is noted nuke it until it’s neutralized then move on leaving civilians and such to military police and provisional administration. The Japanese would probably deploy biochemical weapons against US troops so my tactic of dispersal and “feelers” would minimize losses on allied side.

 

[Athelstane]

Would you recommend this book for learning about Operation Downfall and are there other books you would recommend on this topic?

It's still considered to be an authoritative monograph in the field.

I would put it up there with Frank, Richard B. (1999), Downfall: The End of the Imperial Japanese Empire, New York: Random House, and Giangreco, Dennis M. (2009), Hell to Pay: Operation Downfall and the Invasion of Japan, 1945–1947, Annapolis, MD: Naval Institute Press.

That's a good troika of monographs on the DOWNFALL (in English), if you want a good place to start.

I haven't read the Polmar/Allen or Westheimer books Matt talks about, but he's done more research on this than I have.

 

[Athelstane]

Decisive Darkness? It wasn't 90% bad but it was reaching Paraguay-level bad. It didn't help that the hardliners were purging relatively moderate elements of Japanese society after they tried to surrender.

Yeah, I can't recall what Red had for the casualty estimate, but it wasn't any worse than 1 in 5 or so, if memory serves. Horrible, terrible, crippling, sure, but not virtual annihilation.