The Manhattan Project

J. Samuel Walker's Interview

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J. Samuel (“Sam”) Walker is the former historian of the U.S. Nuclear Regulatory Commission and the author of "Prompt and Utter Destruction: Truman and the Use of Atomic Bombs against Japan." In this interview, he describes the motivations behind President Truman’s decision to authorize the use of the atomic bombs. He explains the key differences between “traditionalist” and “revisionist” interpretations, and identifies weaknesses in each perspective’s argument. He also assesses the role of the Soviet declaration of war against Japan, whether the Japanese were ready to surrender before the bombs were dropped, and American plans for an invasion of mainland Japan. Walker concludes by recalling President Truman’s reaction to the human impact of the bomb.
Manhattan Project Location(s): 
Date of Interview: 
March 14, 2016
Location of the Interview: 
Washington DC

Cindy Kelly: I’m Cindy Kelly. It’s Monday, March 14, 2016. We’re in Washington, D. C., and I have with me the author J. Samuel Walker. My first question to him is to tell me his name and to spell it.

Sam Walker: Well, my name is first initial J. Samuel Walker, so it’s J. S-a-m-u-e-l W-a-l-k-e-r. But, I go by Sam, S-a-m.

Kelly: Absolutely. Well, I know that he is a noted author on the Manhattan Project, and that’s why he’s here today. I wanted him just to give a nutshell summary of how he came to write about the Manhattan Project, what his career has been and his education.

Walker: Well, I’m trained as a historian. I have a Ph.D. in history from the University of Maryland. My field in graduate school was American diplomatic history, and like many of my colleagues who got Ph.Ds. in the early 1970s, I couldn’t find an academic job. I got a job at the National Archives and worked there for three and a half years. I maintained my interest and did some publishing in diplomatic history, but not on the atomic bomb. It wasn’t a topic that greatly interested me at that juncture.

I had read Gar Alperovitz’s book [Atomic Diplomacy: Hiroshima and Potsdam] as an undergraduate, and found that fascinating because it took issue with the myth which had prevailed throughout the ‘50s and ‘60s. That Truman had to use the bomb because the only alternative was an invasion of Japan that would’ve cost hundreds of thousands of lives. So, I read that and I thought, “Well, that’s really interesting,” and then I moved on.

When I left the Archives, I became the historian of the Nuclear Regulatory Commission; a historian at that time, and later the only historian for the NRC. There, I wrote a bunch of books on nuclear power regulation, which again, had nothing to do with the atomic bomb. Except that people would call me up and say, “Was the first bomb used on Hiroshima a plutonium or a uranium bomb?” I didn’t know. And there were other questions like that. People would call the NRC because the first name in the agency’s title was “nuclear,” so they assumed that the historian of the NRC would know.

I was kind of embarrassed by that, so I did some reading. That was around the time of the 40th anniversary of Hiroshima and Nagasaki and a lot of very interesting books came out. I thought, “Well, I’d like to catch up on this topic. It’s been almost 20 years since I was an undergraduate so I think I’ll do some reading and find out some more about this topic.”

As I read, I got interested and I wrote an article, which was published in the Journal of Diplomatic History in 1989 or ‘90, where I surveyed the literature on the atomic bomb and drew some conclusions. The article went well and got, at least by my standards for scholarly articles, more attention than other articles I had written. That’s how I got into the topic.

I got even more interested when the huge controversy broke out a few years later in the early 1990s – ’93, ’94, ’95 – over the Smithsonian’s plan for its ill-fated Enola Gay exhibit. The controversy was fascinating. But it was also a little disarming for me because the historiographical article I had written and published a couple of years earlier constantly got quoted out of context.

Oftentimes scholars on the left side of the spectrum in the atomic bomb controversy quoted me out of context and said, “Look, you know, even the conservative official historian of the Nuclear Regulatory Commission agrees with me.” That really annoyed me, really, really annoyed me, because I thought it was unprofessional. I still think it’s unprofessional. And so at that point in 1995, I thought, “Well, maybe I’ll write a book,” because I thought there was a need for a short book on the decision to use the bomb that would appeal to students and the general public.

My objective was to outline my own views of why Truman used the bomb, which I hadn’t reached any conclusions about yet. I wasn’t certain. I truly went into this topic with an open mind about why the bomb was used, what the considerations were, and, most of all, what the context was in the summer of 1945. I wanted to write a short book, to draw some conclusions, and see where I came out. That’s how the book Prompt and Utter Destruction came about.

It was partly out of the pique on my part because I was tired of being quoted out of context on work not done or related in any way to my job at the NRC. It bothered me that people were using my position as a government historian to advance their own arguments or their own political position. For those two motivations, one of which is more noble than the other, I wrote that book evenings and weekends. I was working all day, writing the history of nuclear power regulation. Evenings and weekends one winter, I wrote Prompt and Utter Destruction. Once I got into it, the topic just doesn’t let go. It’s so fascinating and so interesting. And new documents were opening after the death of Hirohito, so new books were coming out. Since I started that book 20 years ago, I’ve been an atomic bomb decision junkie.

Kelly: That’s great. I want you to pretend I am 13 years old, in the middle of the country, and know nothing about World War II, President Truman, or the context of the decision to drop the bomb. In sort of simple terms for the uninitiated, can you start from the beginning and explain what was going on, what led to this decision, what the factors were? Just give a brief synopsis of your book.

Walker: Yeah, sure. I can do that if we have two or three hours. [Laughter]

Kelly: Yeah, we have some time.

Walker: The context of the bomb, of course, is World War II. There are literally thousands, probably tens of thousands, of books written about World War II. For anyone who wants to understand the modern world, it’s essential to know something about World War II, whether you’re a student or an adult.

If you read anything about World War II, it quickly becomes clear what a horrendous, horrendous world-wide disaster it was for the world. Upwards of 80 million people died. Though the numbers are not exact, they’re huge, and impossible to get your arms around. The amount of destruction in Europe and in other parts of the world was horrific. It’s simply impossible to overstate the destruction, the death, and the horrors of the war.

In that context, the war with Germany ended in early May 1945, but the United States was still at war with Japan. There were no prospects that the war with Japan was likely to end quickly or easily. Everyone knew Japan was in dire straits. The Japanese government certainly knew that. But Japan had given no indication at that point, in the summer of 1945, that they were ready to surrender. So, even though they were defeated, there was no sign they were going to surrender. American policymakers were concerned that the war was going to last perhaps a year or more, with a huge casualty list for American soldiers, Marines, and sailors.

The objective for Truman and his advisors in the summer of 1945 was to find a way to end the war as quickly as possible. The atomic bomb, which was tested for the first time successfully on July 16, 1945, appeared to be the most promising way to end a war quickly. No one knew, or no one assumed, that it would end the war immediately, but it appeared to be the best way, the most likely way to end the war most quickly, and that’s why it was used.

Within that context, the horrors of the war and the desire of Truman and his advisors to end the war as quickly as possible, the use of the bomb, which is so controversial now, was not at all controversial in the summer of 1945. It’s not as though Truman had to choose between advisors who were saying one thing and advisors who were saying something else. No, it was obvious to everyone that the bomb might end the war quickly and shock the Japanese into surrender. So, we should use it. There was no controversy; there was no real deliberation. Once it was ready, we were going to use it.

If you’re the 13-year-old, I would urge you to learn a little bit about World War II. Once you do that, I think you can understand why the bomb was, as I say in the book, an easy and obvious decision for Truman. Truman never agonized over using the bomb. It was just an obvious decision. We’ve got it, the Japanese are not ready to surrender, they’ve given no indication that they’re ready to surrender, and so we use it. And if it does what we think it’s going to do, it might shock them into surrendering.

Kelly: Can you talk a little bit about the ongoing conventional bombing on Japan?

Walker: Yeah, and we kind of lose sight of that. Since the B-29s had been developed – and the B-29 was the latest in airplanes and air warfare, in late 1944, early 1945 – the B-29s had bombed the smithereens out of Japan since early in the year. Because the B-29 had enough range to reach Japan from the Mariana Islands, which we had taken over in 1944, and made it possible for a B-29 to make a roundtrip from Saipan or Guam to Japanese cities and back again. That was something new.

Starting in the fall of 1944, and especially in the early months of 1945, huge fleets of B-29s firebombed, in most cases, or at least many cases, Japanese cities and caused just enormous, enormous destruction. There’s a photograph in my book of what happened at Tokyo. There was a firebombing of Tokyo in March of 1945 that wiped out huge sections of the city of Tokyo. If you look at that photograph, or any photograph, it looks like the photos of damage from the atomic bombs in Hiroshima and Nagasaki.

Bombing of cities and civilians was a well-established practice for the United States and, of course, it had been in Europe, too. There was nothing revolutionary about the use of an atomic bomb against civilian targets. This was viewed as unfortunate by Truman, and especially by Secretary of War Henry Stimson, but it was also viewed as necessary to win the war as quickly as possible. That’s another reason why the decision to use the atomic bomb for Truman was no big decision. It was just a bigger bomb. It was going to cause extensive damage by using a single bomb. But it was not a big step in terms of the power, in terms of the enormity of the destruction it caused, from sending fleets of 300 or 350 B-29s against Japanese cities.

Kelly: At the time, you said that Japan was all but defeated. Can you talk about where they were in terms of military abilities or strength, and then why they didn’t surrender?

Walker: Japan was in dire straits. Japan’s once proud air force was pretty much reduced to training planes. The pilots who had been so skilled were mostly no longer around, either killed or captured, most of them killed. So, the air force was a shell of what it had been when they bombed Pearl Harbor. The Japanese navy, another source of great pride for the Japanese, was virtually eliminated in terms of fighting ability. Japan was suffering from a very effective blockade that the American navy had mounted against the Japanese islands. It was also affected greatly by the bombings of Japanese cities.

The Japanese army was pretty much intact in China. China, or parts of China, had been overrun by the Japanese in the late 1930s. There were huge numbers of well-trained, well-armed, and well-rested Japanese troops in China, other parts of Southeast Asia, and some of the Pacific islands that had been bypassed when the United States hopscotched islands in the Pacific to get closer to Japan proper. So, it had an army, but the armies of Japan were isolated. The Japanese had a large number of troops in Manchuria, which they had overrun after 1931, and they had a large number of soldiers to defend the homeland. It’s just that those troops were not the best equipped, the best trained, the most experienced.

So, in terms of its ability to fight the war, Japan was fatally hampered, and the Japanese government knew that. Why didn’t they surrender? Well, they should have. As early as the summer of 1944, when the United States took over Saipan, Japanese officials—I’ve forgotten which official—a high Japanese official said, “We can no longer conduct this war with any chance of success.”

They knew that, and there was no dissent about that. They knew that as early as the summer of 1944. But it took them another year to decide to surrender. There are various reasons for that. These were not stupid people, but they acted stupidly. That might be the most important reason, but probably not. They wanted to make certain that when they surrendered, if they surrendered, it was done in a way that would be as painless as possible. And, above all, they were determined to keep the emperor on the throne as the head and symbol of the Japanese government.

The question becomes for the United States, for Truman and his advisors, what does it take to force the Japanese to surrender and how many American lives is it going to cost to do that? And that was very much an open question throughout the fall and winter of 1944, and the winter, spring, and summer of 1945.

There were high officials within the Japanese government who said, “Look, we have to surrender, we can’t fight this war. We can’t win this war. Our people are being slaughtered. We have to end the war because if we don’t, continuing the war might be the greatest threat to the emperor.”

They weren’t saying, “Oh, we’re losing tens of thousands of people, women and children.” It’s “We have to do what we have to do to save the emperor, and surrendering with the condition that the emperor be allowed to remain on his throne seems like the best way to do that."

The militants later in the summer of 1945 were saying, “No, no, we can’t do that. We’re not going to surrender unless other conditions are met. We have to keep the emperor on his throne. We also are not going to agree to an occupation of most areas of Japan. We want to disarm ourselves. We want to conduct our own war crime trials.”

Those four conditions. They were, of course, totally unacceptable to the United States and its allies. It was ridiculous for the militants to even think that they might be acceptable. But their thought was “If the United States invades, fine.”

I should go back to American plans for an invasion. An invasion was by far the least desirable and the most feared way of defeating Japan. But the plans went forward as they had to, because most military leaders, including the Army Chief of Staff, General George Marshall, were convinced that an invasion of Japan was going to be necessary to force a Japanese surrender. So plans went forward for an invasion of Japan to begin on or around November 1, 1945.

The militants within the Japanese government were saying, “Yeah, let them come. We are going to kill so many of them when they invade that they will reduce their surrender terms. They will make it easier or more acceptable for us to surrender. That’s the plan. Let them invade. Sure, it’s going to cost millions of Japanese lives.” And they used those numbers. 80 million, I think, was the number that was thrown around, a very large number of Japanese lives. “But that’s okay, because that way we can keep the emperor and we can make surrender, we can make defeat, acceptable.”

Those were the two points of view being argued within the Japanese government and the Japanese hierarchy in the summer of 1945. No conclusion had been reached. The emperor couldn’t make up his mind. He would say one day, “Well, yes, peace would be a good idea. Let’s try for that.” And the next day, he would say, “Well, maybe we should mount a new offensive in China,” which he did say, in fact, in July of 1945.

So that was the situation. You had a Japanese government which knew it was defeated but wasn’t willing to surrender, and that was determined at the minimum to keep the emperor on his throne. The indications are that the idea was not to keep the emperor on his throne as a constitutional monarch, as kind of a figurehead, but to keep the emperor on his throne with the divine powers of a monarch, which is of course what he had before and during the war.

This again was totally unacceptable to the U.S. This was never spelled out, but a lot of good scholarship indicates that that’s what they had in mind up until the final surrender terms were agreed to by the Japanese and the United States after the two bombs and after the Soviet invasion of Manchuria.

Kelly: Wow. Since you mentioned the Soviet invasion, go back to the agreements between the United States and Soviet Union on a Soviet invasion and what initial U.S. attitudes toward Soviet entry into the war were. How that changed, [Secretary of State] Jimmy Byrnes’s fears, and all of this.

Walker: One major objective of [President Franklin D.] Roosevelt at Yalta, which was in January of 1945, was to get [Joseph] Stalin to agree to enter the war against Japan. The Soviets, of course, had been fighting the Nazis, and that had been all they could do as long as the war in Europe was going on.

But by January of 1945, it was clear that the Nazis were all but defeated, and Roosevelt wanted an agreement from Stalin to enter the war against Japan. Japan and Russia had signed a non-aggression agreement, which both countries had observed because it was in their interests to do so. Roosevelt wanted Stalin to agree to come in to the war against Japan, and Stalin agreed to do that three months after the war in Europe was ended.

The reason Roosevelt was so anxious to have that happen is that the Russians could tie down the Japanese troops in Manchuria, of which there were many, so that they wouldn’t be able to be transferred back to mainland Japan. The blockade in January was not as tight as it was later in the spring and summer. But the idea was to get the Soviets to tie down the Japanese troops in Manchuria. For Stalin, it was a good deal because he would not only tie down Japanese troops but also increase his power in Asia.

That was the agreement and the thinking. American policymakers were clear that having the Soviets invade Manchuria would be very helpful for ending the war successfully. I haven’t found any place where anyone ever said that a Soviet invasion of Manchuria in itself would be enough to cause the Japanese to surrender.

When Truman went to Potsdam in July of 1945, his main objective, and he states this in his diary very clearly, was to get Stalin to reaffirm his commitment to entering the war against Japan the following month. The war in Europe had ended in May, and Stalin was due to enter in early August.

Truman’s first meeting with Stalin was an informal luncheon and Stalin said yes, that’s what he was going to do. Truman was delighted, because he’d gotten the main thing that he had gone to Potsdam for without any hassle. Stalin said, “Yeah, I’ll be in August 15.” Truman was – I think “ecstatic” would not overstate how he felt. Stalin didn’t do it as a favor. Of course, he had his own reasons for wanting to invade Manchuria, but still for Truman that was a big thing.

The documents at the time also made clear that although the U.S. thought this would be helpful, again, no one thought it was enough in itself. Truman made a famous diary entry where he wrote down some notes after his luncheon with Stalin. He says, “Fini Japs when that comes about.” Some scholars have said, “Well, here’s proof that Truman thought that a Soviet invasion would be enough to defeat Japan, and so he didn’t need the bomb.”

I’m convinced that we don’t know exactly what Truman meant. It’s something he jotted down. It’s not as though he thought about it. It’s absolutely clear he wasn’t hearing that from his military advisors, from Marshall, or Stimson, or from anybody else who was in charge of conducting the war, that a Soviet invasion in itself would be enough to defeat Japan. Later on, with Japanese documents and with [Operation] Magic intercepts – the United States was intercepting Japanese diplomatic traffic – we have more sources than we once did, and have had for the last 20 years or so.

It’s possible the United States underestimated the impact of the Soviet invasion on Japan, and that the impact was greater than what American policymakers thought at the time in the summer of 1945. But, clearly, at that time, in the context in which they were operating, they did not believe that the Soviet invasion in itself was going to be enough. They thought it would be helpful. It would put more pressure on the Japanese. It would be a shock to the Japanese. But they certainly didn’t conduct or make their policy on the assumption that once the Soviets entered the war, the war would end very soon after.

Did you ask me another part of that question?

Kelly: Well, just James Byrnes.

Walker: Byrnes was convinced that the bomb was going to help him negotiate with the Soviets. Tensions were already growing between the United States and the Soviet Union, and they had been throughout 1945, even before Roosevelt died. Roosevelt was concerned about what Stalin was doing in Eastern Europe. That was a major, major issue. It was the defining issue in the post-war world, in the post-war in Europe world.

Tensions were growing, and Byrnes was concerned about how this was going to affect American positions and American goals in Europe as well as in Asia. Byrnes made it very clear that he thought having the bomb—this is after the bomb has been successfully tested on July 16—was going to help him intimidate or at least impress the Soviets at the diplomatic table.

I don’t think any scholars have really gone to the next step, and I’m not sure there’s any way to go to the next step. It’s not clear to me how he thought that would work. If he was going to wave the bomb and say, “Hey, you know, you better back down, because we’ve got the bomb.” That’s perhaps a non-issue, but Byrnes clearly thought that, and he talked to Truman about that, at least some.

Truman’s attitude was kind of, “Oh, yeah, fine. If they do that, fine, fine.” But that’s not the reason that the bomb was used. The bomb was used for military reasons, because Truman was hearing from his military advisors. Byrnes was not a military advisor in any sense of the term.

Kelly: Can you remind people who he was?

Walker: James F. Byrnes was the Secretary of State. He was in charge of diplomacy, but he was not a military advisor, and the reason Truman used the bomb was that he heard from his military advisors that it might end the war more quickly.

Kelly: By military advisors, you mean George C. Marshall? Who was involved in this?

Walker: Well, the key advisors were Admiral Leahy, who was the White House Chief of Staff. William –“D” I think is his middle initial – William D. Leahy. George C. Marshall, who was the Army Chief of Staff, a man who commanded enormous respect from Truman and from everybody. And Secretary of War Henry L. Stimson, a man of enormous gravity and dignity, who was respected by everybody. Truman didn’t have a great deal of affection – or at least he wasn’t close to Stimson – but he listened to Stimson.

Those were the top three who were advising him on military decisions and military actions. Truman, of course, was a former officer, so he had some sense of the military. He had military experience and that was of value to him as well.

Kelly: Can you tell us a little more about Stimson? Would you say that he was the one who was most closely involved with the actual development of the atomic bomb?

Walker: Yes. Stimson was the Secretary of War, so he was the one who made decisions. Once the Manhattan Project was authorized in the fall of 1941, Stimson was the top official who was responsible for the actions of the Manhattan Project. He appointed General [Leslie] Groves, who was the boot on the ground in terms of running the Manhattan Project. But Stimson was the highest official who was on top of the Manhattan Project on a day-to-day basis, who really understood what was going on without knowing all the technical details. He was keenly aware of progress on the Manhattan Project and what it meant.

By early 1945, when it was clear that the bomb was going to be built and likely to be successful, scientists were telling Stimson – and Groves had told Roosevelt – that the uranium bomb, the U-235 bomb which was used against Hiroshima, wouldn’t need any testing. They were so certain it would work. It was clear by early 1945 that we would have a bomb, because by then it was clear that you were going to have enough U-235 to build at least one bomb. Stimson got very concerned about what this meant for the post-war world in terms of American-Soviet relations, especially. Stimson was very thoughtful about what this means and what the overall impact is going to be, what the long-term impact is going to be, and what is going to happen if and after the bomb is used.

At first he said things that were similar to Byrnes’s view. “This is going to help us with the Russians,” kind of thing. I should know the quote, and I don’t have it at my fingertips—this is going to be the master weapon, this is going to be the decisive weapon. Again, it was kind of vague about how, but the fact that we would have this powerful new weapon, and nobody else would, would be helpful in dealing with the Russians.

As time went on, he became more concerned about what that meant. He was very concerned that Truman was overreacting to what the Soviets were doing in Eastern Europe, that things did not have to be so tense with the Russians. He factored the bomb into his thinking. And, by a month or so after the war ended, he changed his views enough that he was recommending to Truman we approach the Russians, offer to share basic scientific information. Not the engineering details on how to build the bomb, but basic scientific information about atomic energy as a way to try to win their trust. That was a big change from his views five or six months earlier.

Stimson was well informed, he was thoughtful, and he was concerned about what the advent of the bomb meant. But he also was convinced that it should be used as quickly as possible against Japan, that it was the most likely way to end the war as quickly as possible.

Kelly: We should go on with the story chronologically. We have the Japanese in sort of stalemate among their advisors, or at least there’s no sign that people are willing to admit defeat or accept the terms. Can you talk about how the Japanese responded to the bombs?

Walker: Yeah. From the evidence we have – the evidence is ambiguous and there’s still a lot of controversy – scholars who I respect and who’ve looked at Japanese sources are convinced that it was Hiroshima that finally convinced the emperor that the time had come to surrender. It didn’t mean he was ready to surrender on only one condition. He was still apparently talking about how the militants were right to ask for four conditions. But, at least—and, this is exceedingly important—it convinced the emperor the time had come to surrender, that Japan couldn’t continue any longer. You can make a case, I think, that the emperor reached that decision because the atomic bomb looked like it might be a major threat to his own, pardon the expression, rear end. The emperor should’ve ended the war a lot sooner. But Hiroshima finally convinced him that the time had come to end the war.

That was critical, because the emperor had vacillated for years. He knew the conditions were not good. We don’t know exactly how much he knew about how bad things were, but he had a sense. I mean, he did see the destruction the firebombing had caused in Tokyo in March. The first bomb was absolutely essential, the absolute key, to convincing the emperor the time for vacillation had ended. We have to end the war. Do you want me to go on to the second bomb?

Kelly: Yes, please.

Walker: It did not convince the militants, and so the Japanese government was still paralyzed. The emperor did something unusual. He went before the Japanese cabinet, and more importantly, a special body called the Supreme Council for the Direction of the War, which was the highest officials in the government, at least on the military side. It was evenly split between those who thought Japan should surrender on the basis that the emperor remain on his throne, and those, the militants, who said, “No, we have to hold out and if they invade, fine.”

It took a couple of days to find out what had happened at Hiroshima. But it was the day after Hiroshima was bombed, on the seventh, late in the day, Hirohito, the Emperor of Japan, got the word that Hiroshima had been destroyed by a single bomb. It was at that point that he said, “Okay, the war has to end.”

The next day he held a meeting with [Shigenori] Togo, the Foreign Minister, who was a member of the peace faction, and he made it clear that “I want the war to end on acceptable terms.” It wasn’t until the next day that there was a meeting of the Supreme Council for the Direction of the War, in which the emperor made an appearance and said, “I think the war has to end.” He listened to the arguments on both sides and he said, “The war has to end.” There was a lot of opposition from the militants. But the decision was made finally that the United States would be approached for an end to the war on the condition that the emperor be allowed to remain on his throne. That was the key.

But in the meantime, even as this was going on, while Japan was trying to decide what to do and the emperor was becoming convinced that the war had to end, Russia invaded Manchuria. This was the second great shock. The first shock was Hiroshima; the second great shock was the Soviet invasion. This did come as a huge setback for the militants. It’s not exactly clear why it was such a shock, because the Soviets had been mobilizing on the borders for months and the Japanese knew that. Some of the military thought they wouldn’t invade for another few months. Others simply didn’t believe it. It was not an exercise in very prescient analysis of what was going on, and what was facing Japan. But, the Soviets invaded on August 9 and overran Japanese troops in Manchuria very quickly, and in a very costly way in terms of Japanese lives.

Suddenly, the Japanese government was faced not only with the atomic bomb, but also with the Soviet invasion of Manchuria. And, as I indicated earlier, this was probably more of a shock than American leaders realized. The combination of the two finally convinced the Japanese that they had to surrender on the sole condition the emperor be retained.

Historians argue about which is more important. Some say the atomic bomb wasn’t important at all, that it was the Soviet invasion. Some say it was the atomic bomb and the Soviet invasion was not very important. Most scholars now say it’s the combination of two and you can’t possibly sort out which was more important. But, it seems clear to me that the atomic bomb was the most important factor in convincing the emperor and that was a crucial step. So, some combination of the two, and it certainly varied from person to person which was more important, made Japan decide it had to surrender.

After that meeting, which was August 9, the Japanese send a message through Switzerland to the United States: “We’re willing to surrender if – if – the emperor remains on his throne.” I’ve forgotten the phrase, but it could be read to mean, and almost certainly meant, if he retains his power as a divine monarch. It was great news the Japanese sent a message that they were willing to surrender. But there was great concern about what this meant.

Truman gets this and he has a meeting with his top advisors and everyone’s saying, “Great. The Japanese are ready to surrender. Let the emperor remain as a constitutional monarch kind of thing.”

Byrnes, who’d been hearing this from his State Department experts, said, “Wait a minute. Wait a minute. You know, we can’t have this, because this could leave the emperor on his throne with all the powers he has now, which is why we got into the war in the first place.”

Byrnes was also concerned about the political impact of allowing the Japanese to surrender with a condition. Because polls showed after Hiroshima by two to one or more that those Americans who were interviewed said, “No, we shouldn’t allow the Japanese any conditions. Get the emperor out of there. Try him as a war criminal. Hang him.” Byrnes was concerned, as Byrnes always was, about the political effects.

Truman said, “Okay, Jimmy, you go and draft something that will solve this problem.” It was a very delicate problem because we certainly wanted the Japanese to surrender. What we did not want was the emperor to remain as a constitutional monarch.

The message sent back to Japan in response to its peace offer was very vague about the emperor’s status and caused a new crisis in Japan, because the militants were saying, “No, this is not acceptable.” It finally required the advice of Hirohito’s closest advisor. His name was Kido, Lord Keeper of the Privy Seal. I’m not sure exactly what that means and it doesn’t sound all that imposing. But Kido was a boyhood friend of the emperor and his closest advisor. Kido was convinced the war had to end. He convinced Hirohito to appear again before the Supreme Council for the Direction of the War and appeal again for peace.

That did it. The Japanese agreed to surrender on the sole condition that the emperor be retained. The terminology did not say constitutional monarch, but there was nothing in there about him retaining the prerogatives of his office as there was before. On that basis the war ended. But, it was a very, very close call and it was a very, very iffy thing.

One argument has been made by the scholar Richard Frank, and I find it wonderfully convincing. Richard makes the argument – going back to the atomic bomb versus the Soviet invasion – he says that the bomb was essential to convince Hirohito to surrender. But that it was the Soviet invasion that convinced the generals of all those armies in China and other parts of East Asia to surrender. Because there was genuine concern, both among American officials and Japanese officials, that the emperor’s order to surrender would not be obeyed by generals in East Asia, who had huge armies and who could’ve fought on for a very long time at enormous cost to everybody. Richard makes the argument that once the Soviets came in, then the generals out in the field, who were outraged by the idea of surrendering, knew they couldn’t defeat the Soviets. So they went along with it. It’s a very interesting argument that I think makes a very sensible separation of what the impact of the bomb was and the impact of the Soviet invasion.

Kelly: Well, that’s excellent. One thing I wish you could talk a little bit about are the back door negotiations the Japanese were pursuing with the Soviets. It is almost unbelievable that they would be approaching the Soviets, who had their own desires to enter the war and maybe take a piece of some of the things they had lost in the 1905 war. You mentioned Switzerland. There were U.S. channels there; there were Soviet channels there. There were lots of different signals being sent, to Russia, from Russia.

Walker: Yeah. Almost none of it was authorized. I mean, there were some Japanese officials in Switzerland who were saying, “Our government might surrender,” if the unconditional surrender, which is what was U.S. policy at the time, was modified to keep the emperor. But those were not authorized approaches at all. It’s not as though these officials had any approval to do that.

The emperor did decide, in response to the so-called peace faction within the Japanese government – and the militants went along – to approach the Soviets in June of 1945 in hopes that the Soviets would mediate a peace settlement between Japan and the United States. It was a futile hope.

The only reason it was done was because it was the one thing the faction that wanted to surrender and those who wanted to fight on could agree on. So, an envoy was sent to Russia. The Japanese ambassador’s name was [Naotake] Sato.

Sato and Togo, who was the Foreign Minister of Japan, exchanged a lot of telegrams in July of 1945, trying to figure out what to do with the Soviets and how this was going to work. Sato, who I don’t know much about, but obviously had his feet on the ground, was saying to Togo, who was his friend, “Look, if you people want me to approach the Soviets, you have to tell me on what basis we’re willing to surrender.”

Togo didn’t know, because the Japanese couldn’t agree on anything. At one point, Togo must have mentioned something about the four conditions the militants were talking about. Sato kind of knocked his hand against his forehead and said, “You know, that’s impossible. No one’s going to accept that. If things go well, if we’re lucky, and if we’re good, the only thing we can possibly get as a condition is that the emperor remains on his throne.”

Those kinds of wires were going back between Moscow and Tokyo and being intercepted and read in the United States. The exchanges between those two high-level officials, both of whom favored a surrender, made it clear that the Japanese were not ready to surrender.

There’s a famous wire, from July 16, that Togo sent to Sato saying, “Well, it appears that the main obstacle to surrender is the Allies’ demand for unconditional surrender.” Some scholars have said this is proof that the Japanese were ready to surrender, if only we modified the formula for unconditional surrender.

That telegram, or that message, was intercepted, and General Marshall gave it to his Chief of Intelligence, whose name was John Weckerling. Weckerling was a general who had spent a lot of time in Japan, two terms of office, two or three years of peace, as a military attaché, so he knew Japan. Marshall says to Weckerling, “What does this mean? Togo, the Foreign Minister, is saying Japan might surrender. That the main obstacle to surrender is our demand for unconditional surrender.”

Weckerling said, “Well, you know, it could mean that the emperor has intervened in favor of surrender, but the chances of that are remote. It’s possible that the peace faction in Japan has triumphed, but we know from other evidence that that’s not the case, or at least all indications are that that’s not the case. It’s possible that this is a ploy by the Japanese to appeal to war-weariness in the United States, and that seems the most likely.”

Clearly, American officials did not view this message from Togo to Sato as proof that if only we had modified unconditional surrender, the Japanese would’ve quit the war. Clearly, they weren’t ready to do that. It’s one of those documents which is rare in historical research. It’s one of those documents, you read it and you say, “Hey, you know, this really convinces me or changes minds, because it’s clear.”

One of the arguments of the revisionists, who claim that the war could’ve ended more quickly if we had offered to modify unconditional surrender, is that the Japanese were ready to surrender and that the United States knew it. Well, the Weckerling memo makes it clear that the United States did not know it, and in fact was far from convinced – with good reason – that the Japanese were ready to surrender.

Kelly: You mentioned the revisionists. Can you tell us a little bit about these historians?

Walker: Do you want me to name names or–

Kelly: Whatever you think is–

Walker: Well, you know, this has been an enormous controversy. The decision to use the bomb is, I think, in terms of longevity and in terms of bitterness, the most controversial issue in American history.

There are basically two arguments. One is the traditional argument that most of us of a certain age grew up with, and which was set forth by Truman, Stimson, and others after the war. That the president faced a difficult decision between on the one hand authorizing the use of the atomic bomb, and on the other hand authorizing an invasion of Japan that was going to cost hundreds of thousands of American lives. That’s the traditional interpretation.

The revisionists say that’s completely wrong. They believe that Japan decided and was trying desperately to surrender on the sole and reasonable condition that the emperor be allowed to remain on his throne. They don’t say this, but presumably as a constitutional monarch. And therefore, that the traditional interpretation is wrong. They believe the bomb was not necessary to end the war—that it was totally unnecessary—and that it was used for some other reason. The reason that is cited most often is to intimidate the Soviets. This is where they bring in Byrnes as playing a major role in the use of the bomb as a diplomatic weapon against the Soviet Union.

Those are the positions. And as I, and a lot of others, argue – I’m certainly not alone – they’re both seriously flawed. The traditional view because Truman did not face a stark choice between the bomb and an invasion. The invasion was not going to begin until on or around November 1, and a lot of could’ve happened between August and November of 1945. Also the view that if an invasion had been necessary, it would’ve cost hundreds of thousands of lives: there’s simply no contemporaneous evidence that supports that argument. It was made after the war as a means to justify the use of the bomb against a really small number of critics, who in the late ‘40s, early ‘50s, were saying that perhaps the bomb wasn’t necessary. It’s also beyond question that the invasion was not inevitable. I mean, the idea that Truman had to use the bomb because if he didn’t the only other option was an invasion is simply wrong. So, the traditional view in its pure form, that Truman used the bomb to avoid an invasion, simply doesn’t hold up.

Kelly: In the view of the revisionists.

Walker: No, in the view of those of us who are somewhere in between. What I argue is that Truman used the bomb for the reasons he said he did, to end the war as quickly as possible. No one in a position of authority or knowledge, and certainly not his chief and military advisors, told him in the summer of 1945 that if you don’t use the bomb, an invasion is inevitable and it’s going to cost hundreds of thousands of lives. Estimates for lives lost that were projected by military experts in the summer of 1945 were far less than that, and the numbers are far from hard evidence. But there’s no evidence whatsoever that he was ever told that hundreds of thousands of lives would be the cost of an invasion of Japan. That was something that came about later.

My argument is that Truman didn’t have to be told that an invasion would cost hundreds of thousands of lives. He knew it was going to cost a lot of lives, tens of thousands, if an invasion was necessary. He also knew that even without an invasion, the war was still going on. Okinawa had been defeated in late June of 1945, so we had one month when there weren’t any major battlefronts between the end of the Battle of Okinawa and the end of the war, which is July 1945.

In that month, about 775 American soldiers and Marines were killed in combat. About another 2,300 or 2,400 died from other causes, disease, wounds, accidents, whatever. So, you had 3,000 soldiers and Marines who were killed in the month of July of 1945 without any major battlefronts.

You also had sailors being killed. The sinking of the U.S.S. Indianapolis occurred July 28 [misspoke: July 30], 1945, just a horrific event, in which a Japanese submarine attacked and sank the U.S.S. Indianapolis. Of the 1100 [misspoke: 1200] crewmembers, 880 died, either from the explosion of the ship or were stranded in water for a very long time and either died from exposure or from sharks. Just a horrific story.

As long as the war was going on, that was going to happen, and that’s what Truman and his advisors were concerned about. No one had to tell them that the alternative to using the bomb was saving far fewer lives. That number of 3,200 or 3,300 who died in July, that’s just soldiers and Marines, so you have sailors on top of that. That was plenty of reason to use the bomb if it had a chance to end the war as quickly as possible.

I think people lose sight of the fact that the myth grew up after the war that either you use the bomb or lose hundreds of thousands of lives in an invasion. That understates and underestimates the commitment of Truman and his advisors to ending the war as quickly as possible to save any number of lives.

When I give talks about this, I say, “Imagine Truman. An advisor comes up to him and says, ‘Mr. President, you can use the atomic bomb, or the alternative is to lose 40,000 American lives.” Use it. It’s easy.

“Mr. President, you can use the bomb, or if you don’t you’re going to lose an extra 10,000 American lives.” Use it.

“Mr. President, you can use the bomb, or the alternative is to lose an extra 1,000 American lives. Mr. President, you can use the bomb, or the alternative is to lose an extra 100 American lives. Mr. President, you can use the bomb, or the alternative is to lose an extra 10 American lives.”

Well, maybe then I have to think about it, and that’s imaginary, but I think it captures what Truman’s thinking was. It would’ve been a very small number for him to say, “Well, maybe we should think twice about this.”

I don’t know if Truman knew – no one knows if Truman knew – how many soldiers, sailors, and Marines died in the month of July. But Truman could pick up any newspaper from any city in the country and see pictures of soldiers, sailors, and Marines who had died. He certainly knew about that. It bothers me when people underestimate Truman’s commitment to ending the war for exactly that reason. The numbers are insignificant, and they’ve been the cause of whole lot of angry controversy among scholars.

It’s interesting; it’s not decisive to know what the estimates were. What’s important is to keep in mind that’s what Truman cared about. Students, and other people who have been in the audience, have asked me, 3,000 lives, and how many lives did the atomic bomb cost? Well, 166,000 or so in Hiroshima, another 80,000 or 100,000 in Nagasaki. And they say, “Well, how can he do that?”

The fact is, when you’re at a war, or in a war, you don’t make those kinds of calculations. That calculus is not done. The idea is to win the war. Certainly for us in 1945, the idea is to win the war as quickly as possible and save as many lives as possible. How many Japanese lives were cost, or assessed, or how many Japanese were lost by the atomic bomb was incidental. That’s the unfortunate, the tragic part, of any wartime situation. But when it comes to motives, the motive was clearly to save every single one of those lives as possible by ending the war at the earliest possible moment, and the atomic bomb looked like the best way to do that. It’s terribly tragic. If you read about the effects of the bomb, it just breaks your heart. I think we lose sight of the fact, or some people lose sight of the fact, that the Japanese should’ve surrendered in 1944, and that they prolonged the war for reasons which seem to me to be illegitimate.

One well-known factor in this whole thing was when Secretary Stimson came in after Truman returned from Potsdam. He met with Truman the morning of August the tenth, and showed him for the first time photographs of the damage to Hiroshima. Stimson said to Truman, “You know, 100,000 people probably died.” No one knew for certain, but the estimate that he gave to Truman was 100,000 lives were lost at Hiroshima.

I think that had a major impact on Truman. Because he went to a Cabinet meeting later that day and in talking about the war he said for the first time, “I have issued an order that we will use no more atomic bombs without my express authorization,” which hadn’t happened with the first two bombs.

He said he was greatly bothered by the fact that the bomb at Hiroshima had killed 100,000 people. He was greatly bothered by the fact that 100,000 people had died, and he didn’t like the idea of “killing all those kids.” So Truman, for the first time, became aware of what the human impact of the bomb was. I think we all need to be keenly aware of that, and yet we shouldn’t lose sight of what the motives were in using the bomb.

I mentioned the weaknesses in the traditional argument, and I should also mention what I consider fatal weaknesses in the revisionists’ argument. There are two central parts of the revision argument, and we know beyond a shadow of a doubt that they’re both incorrect.

One is that the Japanese were trying to surrender. Japanese sources that have opened since Hirohito died in 1989 make it abundantly clear that Japan in fact had not decided to surrender before Hiroshima. Scholars who have used Japanese, of which there are several who are very good and who span the spectrum of opinion on Truman’s decision to use the bomb, all agree that Japan had not decided to surrender before Hiroshima. That’s one major element of the revisionists’ argument that simply doesn’t hold up.

The other is, and I think I got waylaid when I started talking about the Weckerling memo and how it’s one of those rare memos that really makes clear that the United States government did not believe that Japan was ready to surrender. The revisionists have said, “Oh, you know, Japan had decided to surrender and the U.S. knew that.” Well, the Weckerling memo makes it abundantly clear that, in fact, the U.S. didn’t know that and didn’t believe that.

There are other major problems with the revisionists’ argument. They put much more emphasis on the feasibility of the war ending without the bomb by taking advantage of other alternatives. I don’t think I want to get into the other alternatives. But the most common argument is if only we had modified unconditional surrender, and they use that Togo memo to Sato to say, “If only we had modified that, the war would’ve ended.” We know that’s not true now and we know that the U.S. didn’t believe that either.

So, the two major mainstays of the revisionists’ argument simply don’t hold any water based on recent, fairly recent, documents which have become available and some outstanding scholarship. What is defensible, and in fact true, about the revisionists’ argument is that impressing the Soviets was part of the motivation for the use of the bomb, but a secondary part, a bonus. The primary reason was to end the war as quickly as possible, and if it impressed the Soviets, well, fine, great, that’s a nice little addition.

There were other reasons as well. General Groves was concerned about if the bomb didn’t work, or if it wasn’t used, how would he explain what he had spent $2 billion on? So there were those kinds of reasons. Hatred of the Japanese, vengeance, and all those things played a role, but the primary reason was to get the war over hopefully as quickly as possible. So there are severe problems with both the traditional interpretation and the revisionist interpretation, and I and a lot of other very able scholars come out somewhere between.