You've got some timelines mixed up. The Japanese were utterly undeterred by the 1st bomb. They assessed that it was as bad as a bad fire-bombing raid, which had already devastated most of their country.
The 2nd bomb worried them because Truman followed it up with a statement that they would continue to use nukes on a regular basis. They leaked fake information to Japan that we had at least 12 more ready to go. Japanese Air Defense at this time was in shambles, which meant that there was no capacity for Japan to avoid the attacks.
That's when it started to become clear that the war was fundamentally unsustainable. The Americans clearly seemed intending to invade, and it was also clear that the Soviet would join. The absolute catastrophe of the Japanese campaign against the Soviets in Manchuria piled on top of that showed that the war was well and truly hopeless. The militarists had led the IJN and IJA to complete annihilation, the country was literally on fire, and now it looked like it was going to dealt a true death blow by a pincer invasion of the most violent type the world had ever seen. The Americans and Soviets would, undoubtably, burn their way through Japan. The violence of the invasions could be easily be predicted with the Soviet conduct in Eastern Europe (including mass rape), and the Marines conduct in Iwo Jima (burn every single hole and cave). The best case is that, for some reason, the Americans decide to go with a blockade, and therefore create a weaponized famine to starve millions of people to death into making Japan surrender. The Nazis fighting to the last man as even the Wermacht turned on them shows the best case of what could happen to Japanese unity.
The continuation of the war was a existential, civilization-level, threat to Japan.
Hiro Hito must have seen the writing on the wall at this point, and decided the only sane thing was to try and surrender, which is why the militarists tried to coup the government and have him assassinated. At a certain point, it's pretty clear that the militarists had truly gone fucking insane, and were just trying to kill everyone, and themselves, in order to avoid admitting that they fucked up.
and the Marines conduct in Iwo Jima (burn every single hole and cave).
Honestly, I think Okinawa actually had far more of an influence than Iwo Jima did. It tends to get overlooked for some reason, but I would argue for Okinawa because it was the first major time the US had to deal with Japanese civilians in a significant way (the only possible other one before that being Saipan, and that was on a much smaller scale).
Not only do you have the same issue of the US have to burn the Japanese out of every hole and cave, you now add in the civilian population being utterly terrified and acting irrationally because of all the propaganda that they had been fed, like the Marines being cannibal psychopaths or the Air Force being more akin to a natural disaster than a military branch. And as such, the civilians either did hopeless attacks with improvised weapons because at least they will die swinging before a Marine eats their corpse, or they would just kill themselves so they didnt have to live with it. And no amount of sometimes literal begging from the US military stopped it.
So not only would you have the Japanese wanting to make that happen on a civilizational scale on the home islands, you had the US military traumatized by the fact that they would have to do it again on an even bigger scale than Okinawa. At least for me, it is absolutely no coincidence that a ton of the US high command that was in the know about the existence of the nukes went from "They are a nice backup option" to "They will be our first tool" after Okinawa.
I'm not going to deny that Okinawa may have had more of an impact than Iwo Jima. Okinawa was wetter, muddier, slower, involved more civilians, and may have even bloodier. I think that's also where Kamikaze attacks were highly successful. Even veterans of both battles have said they preferred Iwo over Oki. Which, given the context, is a fucking insane thing to say.
The strangest thing is, I think if Operation Olympic had gone through, the surrender rate would actually have been much higher. The US military basically assumed that not even 1% of Japan's civilians, let alone soldiers, would surrender, and that experience was driven home especially by Okinawa. The Japanese troops on those islands were heavily propagandized and reminded that fighting to the last man was an absolute imperative, because the trauma on the US military was a strategic objective. It also represents a terrible miscalculation. Instead of the Americans saying, "My God, we'll have to kill every single man, woman, and child; we should reconsider", they said, "My God, we'll have to kill every single man, woman, and child; we need more flame tanks". Big oof. Historically, I think that might have worked on the English, but the Americans are a more violent people than most Europeans, and even with all our Liberal sensibilities, our propensity for murder is shockingly high.
Had the invasion gone forward, I think the first year would have been the worst we'd ever have seen, probably increasing the dead to a full million on the American side, but by 1946 I think we would have been seeing mass surrender by Japanese civilians. Surrender isn't actually unheard of to Japanese society, it's just that Japanese militarism tried to pathologize it.
You've got some timelines mixed up. The Japanese were utterly undeterred by the 1st bomb. They assessed that it was as bad as a bad fire-bombing raid, which had already devastated most of their country.
The 2nd bomb worried them because Truman followed it up with a statement that they would continue to use nukes on a regular basis. They leaked fake information to Japan that we had at least 12 more ready to go. Japanese Air Defense at this time was in shambles, which meant that there was no capacity for Japan to avoid the attacks.
That's when it started to become clear that the war was fundamentally unsustainable. The Americans clearly seemed intending to invade, and it was also clear that the Soviet would join. The absolute catastrophe of the Japanese campaign against the Soviets in Manchuria piled on top of that showed that the war was well and truly hopeless. The militarists had led the IJN and IJA to complete annihilation, the country was literally on fire, and now it looked like it was going to dealt a true death blow by a pincer invasion of the most violent type the world had ever seen. The Americans and Soviets would, undoubtably, burn their way through Japan. The violence of the invasions could be easily be predicted with the Soviet conduct in Eastern Europe (including mass rape), and the Marines conduct in Iwo Jima (burn every single hole and cave). The best case is that, for some reason, the Americans decide to go with a blockade, and therefore create a weaponized famine to starve millions of people to death into making Japan surrender. The Nazis fighting to the last man as even the Wermacht turned on them shows the best case of what could happen to Japanese unity.
The continuation of the war was a existential, civilization-level, threat to Japan.
Hiro Hito must have seen the writing on the wall at this point, and decided the only sane thing was to try and surrender, which is why the militarists tried to coup the government and have him assassinated. At a certain point, it's pretty clear that the militarists had truly gone fucking insane, and were just trying to kill everyone, and themselves, in order to avoid admitting that they fucked up.
Honestly, I think Okinawa actually had far more of an influence than Iwo Jima did. It tends to get overlooked for some reason, but I would argue for Okinawa because it was the first major time the US had to deal with Japanese civilians in a significant way (the only possible other one before that being Saipan, and that was on a much smaller scale).
Not only do you have the same issue of the US have to burn the Japanese out of every hole and cave, you now add in the civilian population being utterly terrified and acting irrationally because of all the propaganda that they had been fed, like the Marines being cannibal psychopaths or the Air Force being more akin to a natural disaster than a military branch. And as such, the civilians either did hopeless attacks with improvised weapons because at least they will die swinging before a Marine eats their corpse, or they would just kill themselves so they didnt have to live with it. And no amount of sometimes literal begging from the US military stopped it.
So not only would you have the Japanese wanting to make that happen on a civilizational scale on the home islands, you had the US military traumatized by the fact that they would have to do it again on an even bigger scale than Okinawa. At least for me, it is absolutely no coincidence that a ton of the US high command that was in the know about the existence of the nukes went from "They are a nice backup option" to "They will be our first tool" after Okinawa.
I'm not going to deny that Okinawa may have had more of an impact than Iwo Jima. Okinawa was wetter, muddier, slower, involved more civilians, and may have even bloodier. I think that's also where Kamikaze attacks were highly successful. Even veterans of both battles have said they preferred Iwo over Oki. Which, given the context, is a fucking insane thing to say.
The strangest thing is, I think if Operation Olympic had gone through, the surrender rate would actually have been much higher. The US military basically assumed that not even 1% of Japan's civilians, let alone soldiers, would surrender, and that experience was driven home especially by Okinawa. The Japanese troops on those islands were heavily propagandized and reminded that fighting to the last man was an absolute imperative, because the trauma on the US military was a strategic objective. It also represents a terrible miscalculation. Instead of the Americans saying, "My God, we'll have to kill every single man, woman, and child; we should reconsider", they said, "My God, we'll have to kill every single man, woman, and child; we need more flame tanks". Big oof. Historically, I think that might have worked on the English, but the Americans are a more violent people than most Europeans, and even with all our Liberal sensibilities, our propensity for murder is shockingly high.
Had the invasion gone forward, I think the first year would have been the worst we'd ever have seen, probably increasing the dead to a full million on the American side, but by 1946 I think we would have been seeing mass surrender by Japanese civilians. Surrender isn't actually unheard of to Japanese society, it's just that Japanese militarism tried to pathologize it.