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There has been some controversy on the true effect of the atomic bombing of Japan. Was it the bomb, or the Soviet declaration of war that ended WWII?(r/AskHistorians)
Whether they had an accurate appraisal of the situation or not, the only things that matter in determining what ended the war are the subjective reasons that Japanese leaders chose to surrender when and how they did. Whether the US made the right choice is a separate question.
Using the diaries and records of the meetings among Japanese leaders, Hasegawa has conclusively demonstrated that the atomic bomb had less of an influence on the debates in Tokyo than the standard American narrative would suggest. These strongly suggest that Soviet entry into the war was the critical point that made fighting on untenable, and also that up until that point, they were still expecting to fight the Allies on Japanese soil, despite the use of the bombs.
It’s important to realize that the destruction of Hiroshima and Nagasaki were not, at first, particularly novel experiences for Japan. The firebombing of Tokyo had a higher death toll (estimates from 80,000-200,000; 130,000 a commonly cited figure) than either in terms of people killed outright. The true horror of the atomic bombs did not become clear until weeks, months and years after the fact (For Hiroshima, roughly 70,000 people died in the initial blast, 100,000 by the end of the year, and over 200,000 in 5 years). While the new bomb did condense thousands of planes worth of destruction into a single bomb, the actual level of destruction was not higher at the time that the Japanese government was making the decision to surrender. Disease and deaths from radiation would later change the balance of destruction, but it is incorrect to assume that the Japanese command was aware of the delayed effects of atomic bombs.
This is not to say that the bombs did not have an effect, because they undoubtedly did. They sped the decision to capitulate, even if the Soviet entry into the war was the deciding factor. The bomb was also influential in solidifying Hirohito’s stance on surrender, and gave the peace faction some ammunition against the war faction.
Alright, that’s the short answer. Last time this debate was had, there was a fair amount of calling out over sources and proof, so the following basically recapitulates the above as a timeline with references to Hasegawa and his sources.
Although the Soviet Union had renounced the Japanese neutrality pact and the Japanese ambassador knew that looking for soviet mediation in the surrender was a lost cause, the sources indicate that Japanese leaders largely ignored their ambassador’s advice, and insisted on pursuing the possibility of Soviet mediation (all quotes and page numbers are from Hasegawa Racing the Enemy)
June 18th, the [Supreme War Council](http://en.wikipedia.org/wiki/Supreme_War_Council_(Japan)) decided to pursue “option 3,” seeking Soviet mediation, and Hirohito endorsed this action in a meeting with the Big 6(The Supreme War Council, minus the Emperor) on June 22nd (106).
June 30th, Sato, Ambassador to Moscow, telegrammed Togo, the Minister of Foreign Affairs and one of the Big 6, to tell him that such a plan “…is nothing but pinning our hopes to the utterly impossible.” Togo basically told him to do it anyway (123).
July 12, Not to be deterred, Hirohito decided that Japan should try a little harder if negotiations weren’t going well, and appointed Prince Konoe special envoy to Moscow to secure Soviet mediation. The same day Togo Telegrammed Sato and asked him to relay their intentions to Molotov, but Sato was unable to contact him before he departed for Potsdam. This clearly shows that even though their ambassador had been rebuffed, the Japanese high command either did not relay the full message up to the Emperor, or that they did not understand the gravity of the situation (123-124). Sato’s messages of the impossibility of this task continued through the rest of July, and Togo responded by telling him that seeking Soviet mediation was the imperial will (144).
August 2nd, Togo continued to reject multiple ambassadors’ advice that Japan should accept the Potsdam Procalmation, and told Sato that the Emperor was concerned about the progress of the Moscow negotiations, adding that “the Premier and the leaders of the Army are now concentrating all their attention on this one point”(172).
Aug. 7, After the Hiroshima bomb, Togo sent another telegram to Sato in Moscow regarding the Konoe mission, stating that the situation was getting desperate and that “We must know the Soviet’s attitude immediately” (185). Obviously they still hadn’t given up hope on Soviet aid. Moreover, the possibility of Soviet mediation still seemed to be an alternative to simply surrendering unconditionally, even to the peace party. Molotov and Sato met on the 8th, and Molotov read him the declaration of war against Japan at that meeting. Sato’s telegram informing Tokyo never arrived.
Aug. 9th, Japanese Domei News intercepts a radio broadcast of the Russian declaration of war and Tokyo learns of it. Early in the morning Togo and top foreign ministry officials met and decided there was no choice but to accept the terms of the Potsdam Proclamation (197). Togo then secured the agreement of Navy Minister Yonai and Prince Takamatsu. Hirohito independently learned of the Soviet entry to the war and summoned Kido at 9:55 am, telling him “The Soviet Union declared war against us, and entered into a state of war as of today. Because of this it is necessary to study and decide on the termination of the war,” according to Kido’s Journal (198). Hearing this, Prime Minister Suzuki deferred to the Emperor’s wishes and convened the War Council. Clearly, among the peace party, Soviet entry to the war swayed them to end the war not through Soviet mediation, but by accepting the Potsdam proclamation.
The Army had done a study in July concluding that although Soviet attack was possible, it likely wouldn’t happen until Feb. 1946. That was obviously wishful thinking, but the war party was shocked, nonetheless. The diary of Army Deputy Chief Kawabe notes considerably more shock regarding the Soviets than it does regarding the bombing of Hiroshima. Nonetheless, Army Minister Amami was not ready to surrender.
At that meeting, the Big 6 learn of the Bombing of Nagasaki. According to the official history of the Imperial General Headquarters, “There is no record in other materials that treated the effect [of the Nagasaki Bomb] seriously.” Similarly, neither Togo nor Toyoda mention it in their memoirs of the meeting (204). In the meeting the war party continued to defend the idea of defending the home islands to force favorable terms, but steadily wilted under probing questions from the peace faction. By the end, they had agreed to accept Potsdam, but still debated 1 condition vs 4.
After this, members of the peace faction arranged to meet with Kido urging him to urge the Emperor to support a single condition acceptance (“preservation of the imperial house” or “preservation of the Emperor’s status in national laws” depending on who phrased it). Kido then met with the Emperor. The details of that meeting are not recorded, however, afterward the Emperor agreed to call an imperial conference, at which he supported Togo’s proposal, saying “My opinion is the same as what the Foreign minister said.” All the members, including the war party signed the document (213).
Between then and Aug. 15th there were some serious issues, including a reworking of unacceptable language and the small matter of an attempted coup when members of the war party thought better of their decision, but at this point the matter is close enough to its final form.
As we have seen, it is true that the Emperor was the deciding “vote,” but, as the deliberations show, his decision wasn’t much of a decision at all and occurred largely because he was convinced by those who were convinced to surrender by Soviet declaration of war to put his weight behind the plan they had laid out. His own statements also show the effect that Soviet Entry to the war was a major concern for him as well. Similarly, it was the Soviet entry and lack of the possibility of negotiated peace that weakened the war party’s case to the point that they acquiesced to the acceptance of Potsdam, albeit with 4 conditions, at the meeting earlier in the day.
Finally, to reiterate, the Emperor’s speech on Aug. 15th is not sufficient evidence to determine the reasons for ending the war. First, that speech was public and therefore edited for public (as well as American) consumption. Second, it is only one of several sources. Of the contemporary sources on why Japan surrendered, 3 (Konoe on Aug.9th, Suzuki’s statements to his doctor on Aug. 13th, and Hirohito’s Imperial Rescript to Soldiers and Officers on Aug. 17th) speak exclusively about the Soviets, 2 (Hirohito’s Imperial Rescript on the 15th and Suzuki’s statements at the cabinet meeting of Aug. 13th) speak exclusively about the bombs, and 7 speak of both (297-298). Obviously both played a role, but a close examination of the process of decision making gives the deciding edge to Soviet entry.
Hirohito’s was the final and deciding vote, and he frequent mentioned of the Atomic bomb as a deciding factor. See Frank’s chapter in this book. I disagree for 2 reasons: it overestimates the agency of the emperor, and ignores his references to the Soviet entry to the war as ending the possibility of the Soviet mediated surrender that he had been pushing for.