Richard B. Frank had an absolutely fascinating story about Why Truman Dropped the Bomb. He reports on Magic intercepts of Japanese diplomatic and military communications that we had access to during much of the war. Some of this information has just been declassified since the mid 1990s so a lot of what had been written about why Truman decided to drop the bomb is incomplete. One argument that has been made is that the Japanese were ready to surrender before we dropped the bomb and the evidence that is used is based on the approaches that the Japanese ambassador to Moscow, Ambassador Sato, had made to the Soviet government. The argument goes that if only we had let the Japanese know that they could keep the Emperor, they would have been willing to surrender. But somehow, we never made that offer and critics of Truman's decision believe that if we had let them know that they could keep their Emperor, we would not have had to drop the bomb. However, the Magic intercepts include this conversation between Sato with the military Foreign Minister Togo.

An inner cabinet in Tokyo authorized Japan's only officially sanctioned diplomatic initiative. The Japanese dubbed this inner cabinet the Big Six because it comprised just six men: Prime Minister Kantaro Suzuki, Foreign Minister Shigenori Togo, Army Minister Korechika Anami, Navy Minister Mitsumasa Yonai, and the chiefs of staff of the Imperial Army (General Yoshijiro Umezu) and Imperial Navy (Admiral Soemu Toyoda). In complete secrecy, the Big Six agreed on an approach to the Soviet Union in June 1945. This was not to ask the Soviets to deliver a "We surrender" note; rather, it aimed to enlist the Soviets as mediators to negotiate an end to the war satisfactory to the Big Six--in other words, a peace on terms satisfactory to the dominant militarists. Their minimal goal was not confined to guaranteed retention of the Imperial Institution; they also insisted on preservation of the old militaristic order in Japan, the one in which they ruled.

The conduit for this initiative was Japan's ambassador in Moscow, Naotake Sato. He communicated with Foreign Minister Togo--and, thanks to code breaking, with American policymakers. Ambassador Sato emerges in the intercepts as a devastating cross-examiner ruthlessly unmasking for history the feebleness of the whole enterprise. Sato immediately told Togo that the Soviets would never bestir themselves on behalf of Japan. The foreign minister could only insist that Sato follow his instructions. Sato demanded to know whether the government and the military supported the overture and what its legal basis was--after all, the official Japanese position, adopted in an Imperial Conference in June 1945 with the emperor's sanction, was a fight to the finish. The ambassador also demanded that Japan state concrete terms to end the war, otherwise the effort could not be taken seriously. Togo responded evasively that the "directing powers" and the government had authorized the effort--he did not and could not claim that the military in general supported it or that the fight-to-the-end policy had been replaced. Indeed, Togo added: "Please bear particularly in mind, however, that we are not seeking the Russians' mediation for anything like an unconditional surrender."

This last comment triggered a fateful exchange. Critics have pointed out correctly that both Under Secretary of State Joseph Grew (the former U.S. ambassador to Japan and the leading expert on that nation within the government) and Secretary of War Henry Stimson advised Truman that a guarantee that the Imperial Institution would not be eliminated could prove essential to obtaining Japan's surrender. The critics further have argued that if only the United States had made such a guarantee, Japan would have surrendered. But when Foreign Minister Togo informed Ambassador Sato that Japan was not looking for anything like unconditional surrender, Sato promptly wired back a cable that the editors of the "Magic" Diplomatic Summary made clear to American policymakers "advocate[s] unconditional surrender provided the Imperial House is preserved." Togo's reply, quoted in the "Magic" Diplomatic Summary of July 22, 1945, was adamant: American policymakers could read for themselves Togo's rejection of Sato's proposal--with not even a hint that a guarantee of the Imperial House would be a step in the right direction. Any rational person following this exchange would conclude that modifying the demand for unconditional surrender to include a promise to preserve the Imperial House would not secure Japan's surrender. (Emphasis added)

So, our people in Washington knew that an offer to let them keep the Emperor was not going to be sufficient to get them to surrender. Perhaps, this exchange between Sato and Togo is why we did not make that offer. It seems pretty clear from this exchange that the military in Japan, who controlled the government was not on board with any surrender proposals. And any surrender that had let them still have control of the government would have been worthless.

Another point that Frank brings up in this article that I hadn't known is that the Japanese were fully aware of our invasion plans of Kyushu and had built up their defenses to such a degree that our military planners were close to dropping that invasion plan.

Starting with the publication of excerpts from the diaries of James Forrestal in 1951, the contents of a few of the diplomatic intercepts were revealed, and for decades the critics focused on these. But the release of the complete (unredacted) "Magic" Far East Summary, supplementing the Diplomatic Summary, in the 1990s revealed that the diplomatic messages amounted to a mere trickle by comparison with the torrent of military intercepts. The intercepts of Japanese Imperial Army and Navy messages disclosed without exception that Japan's armed forces were determined to fight a final Armageddon battle in the homeland against an Allied invasion. The Japanese called this strategy Ketsu Go (Operation Decisive). It was founded on the premise that American morale was brittle and could be shattered by heavy losses in the initial invasion. American politicians would then gladly negotiate an end to the war far more generous than unconditional surrender. Ultra was even more alarming in what it revealed about Japanese knowledge of American military plans. Intercepts demonstrated that the Japanese had correctly anticipated precisely where U.S. forces intended to land on Southern Kyushu in November 1945 (Operation Olympic). American planning for the Kyushu assault reflected adherence to the military rule of thumb that the attacker should outnumber the defender at least three to one to assure success at a reasonable cost. American estimates projected that on the date of the landings, the Japanese would have only three of their six field divisions on all of Kyushu in the southern target area where nine American divisions would push ashore. The estimates allowed that the Japanese would possess just 2,500 to 3,000 planes total throughout Japan to face Olympic. American aerial strength would be over four times greater.

From mid-July onwards, Ultra intercepts exposed a huge military buildup on Kyushu. Japanese ground forces exceeded prior estimates by a factor of four. Instead of 3 Japanese field divisions deployed in southern Kyushu to meet the 9 U.S. divisions, there were 10 Imperial Army divisions plus additional brigades. Japanese air forces exceeded prior estimates by a factor of two to four. Instead of 2,500 to 3,000 Japanese aircraft, estimates varied between about 6,000 and 10,000. One intelligence officer commented that the Japanese defenses threatened "to grow to [the] point where we attack on a ratio of one (1) to one (1) which is not the recipe for victory."

So factor in this information with the diplomatic intercepts when looking at what information Truman was basing his decision on. He was being told that our planned invasion was going to lead to many more casualties and be much more problematical than we had originally thought. And this was after the tens of thousands of deaths on Okinawa had shown us what a Japanese army fighting until death could do to our invading armies. In fact, it is not even clear that the invasion would have had the endorsement of Truman's military advisers in August, 1945. What were the alternatives if we'd scrapped the plans to invade at Kyushu? All this has to be taken into account when evaluating Truman's decision.

A final consideration is that thousands of captive Asians were dying daily under Japanese control. Every day that we delayed if we had tried some sort of embargo to starve the Japanese until they surrendered would have meant death to more and more innocent civilians in the captive countries that Japan controlled.

This brings us to another aspect of history that now very belatedly has entered the controversy. Several American historians led by Robert Newman have insisted vigorously that any assessment of the end of the Pacific war must include the horrifying consequences of each continued day of the war for the Asian populations trapped within Japan's conquests. Newman calculates that between a quarter million and 400,000 Asians, overwhelmingly noncombatants, were dying each month the war continued. Newman et al. challenge whether an assessment of Truman's decision can highlight only the deaths of noncombatant civilians in the aggressor nation while ignoring much larger death tolls among noncombatant civilians in the victim nations.

Yes, dropping the nuclear bomb was a terrible decision. But, it was the least bad choice that Truman had. This relatively recently released information makes it clear that the information Truman had before him made the other choices even worse than what we had known before.

I thought I'd followed the debate on Truman's decision rather closely and when I teach it, I give the kids lots of primary and secondary sources and have them debate the decision. But I had never heard about that diplomatic exchange and that the Japanese knew all about our invasion plans. And, unsurprisingly, that information has not penetrated the textbooks that there are for high school students. Almost every textbook has some discussion of the pro and con arguments about Truman's choice, but, even though they were published since the release of these documents, that part of the story has not made its way yet into the standard textbooks. I'll add in this information to my debate materials, but I think it will make it even harder for the con side debating the question.