From my student years in Japan, I well remember one day walking out of a class on Japanese literature with my Waseda University professor. We were discussing the relations of our two countries when unexpectedly he asked me, “Would America have dropped an atomic bomb on Germany?” Surprised by the question and not having studied the issue, I could only answer, “I don’t know.” He was wondering, as many Japanese have, whether racism had played a part in the decision. The question stuck with me.

When I became a university professor myself and began teaching Japanese history, I found that the American decision to use the bomb on Hiroshima and Nagasaki sparked immediate interest with my own students. How was it, the American students wondered, that our country is the only one to have used the bomb on other people? Responding to their interest and my own wish to explore the topic, I created a new course – an honors seminar – to address the American decision to use the atomic bomb. I began the seminar by introducing some different interpretations. And as new interpretations emerged in the more-than twenty-five years that I have taught the course, I focused the seminar not simply on the decision itself but on its historiography as well. Why was it, I posed the question, that historians studying the same event, apparently examining the same facts, came to such different and often conflicting interpretations?

I found that the widely varying ways in which historians have interpreted the decision to use the atomic bomb on Hiroshima and Nagasaki proved a rewarding way to explore the nature and function of the historian’s craft. Tracing the anatomy of the debate over the use of the bomb offers a valuable means for understanding the many aspects of the historical profession and the varieties of history. The Hiroshima decision has often been called the most controversial decision any American president has made. Historians have interpreted it in more divergent ways than perhaps any other event in recent American history. The motivation and causes of the decision have provoked continuing controversy. “No single decision ever made by an American president has aroused more discussion and debate,” wrote McGeorge Bundy, President John Kennedy’s National Security Advisor, in his important study of the first fifty years of policymaking on the bomb.Footnote ¹

Because of its controversial nature and its huge historical importance, it has also been “one of the best studied decision-making cases in history.”Footnote ² Primary source material, existing archives, have been mined by historians and subjected to a wide range of debate about the issues raised.Footnote ³ A mountain of literature has grown as historians and others have obsessively written about it. “A complete bibliography of relevant writings on the bomb,” writes one historian, “could easily comprise a book.”Footnote ⁴ Despite the extensive research and debate over the topic, historians have come to so many varying and conflicting interpretations that the British military historian John Keegan concluded that “historians are committed to controversy as a way of life, and [the Hiroshima] controversy may never be settled.”Footnote ⁵

There are many reasons why historians have devoted so much attention to the Hiroshima decision, some immediately obvious and others that require more reflection. First, and most profoundly, the advent of nuclear weapons was an existential event. For the first time in human history, humans had the capacity to let loose weapons that could bring civilization to an end. In discussing its possible use in the war, Secretary of War Henry Stimson, who was given charge of the project to build the atomic bomb, said that it was not simply a new weapon but rather represented “a new relationship of man to the universe.”Footnote ⁶ With the enormous horror of the new weapon came the realization that a great scientific achievement threatened humankind’s very survival. Its first use signaled to human beings the tenuousness of their future. For the Indian leader Mahatma Gandhi, recalling the moment he heard of the use of the bomb, “I did not move a muscle. I said to myself, ‘Unless the world now adopts nonviolence, it will spell certain suicide for mankind.’”Footnote ⁷ The French philosopher Albert Camus wrote on August 6, 1945, “Faced with the terrifying perspectives which are opening up to humanity, we can perceive even better that peace is the only battle worth waging. It is no longer a prayer, but an order which must rise up from peoples to their governments – the order to choose finally between hell and reason.”Footnote ⁸

The Hiroshima decision initiated what scholars now call “the nuclear revolution.” The advent of nuclear weapons, their proliferation, technological advance into thermonuclear weapons, the strategies for their possible use either in conflict or deterrence, all brought about a rethinking of the geopolitical order.Footnote ⁹ The eminent scholar of international relations Hans Morgenthau wrote that nuclear weapons had forever changed the nature of foreign policy. Nuclear weapons represented “the only real revolution which has occurred in the structure of international relations since the beginning of history, because it has radically changed the relationship between violence as a means of foreign policy and the ends of foreign policy.”Footnote ¹⁰ The newly present threat of nuclear holocaust had to weigh heavily on leading diplomats. As Henry Kissinger wrote in the opening lines of his first book: “It is not surprising that an age faced with the threat of thermonuclear extinction should look back nostalgically to periods when diplomacy carried with it less drastic penalties, when wars were limited and catastrophe almost inconceivable.”Footnote ¹¹

In addition to the existential implications of the first use of nuclear weapons, historians have focused their attention on the Hiroshima decision because it is a central event in the twentieth century that changed the course of international politics. At the turn of the millennium, in 1999, in a poll taken of prominent journalists and scholars, the decision to use the atomic bomb on Hiroshima and Nagasaki was chosen as the most important event of the twentieth century.Footnote ¹² This horrific event was at the center of the major developments of our time: the end of World War II, the beginning of the atomic age, the establishment of the American world order, and the Cold War nuclear arms race. Historians have linked the decision to use the bomb with all of these major developments and, therefore, placed it at the center of modern history.

Historical controversy has involved many issues:

1. 1. What motivated decision-makers to use this horrific new weapon?

2. 2. Was it necessary to use the bomb if Japan was already defeated and on the verge of surrender?

3. 3. Were there not viable alternatives such as a demonstration of the bomb or a naval blockade or modification of unconditional surrender policy or waiting for Soviet entry into the war?

4. 4. Did the use of the bomb save lives by averting an invasion?

5. 5. Was the second bomb on Nagasaki necessary?

6. 6. Can the bombs be morally justified?

To these and many other questions historians continue to offer many conflicting interpretations.

Another reason for such intense and ongoing attention by historians arises from the continuing public debate on the topic. Public opinion polls in recent years show that the majority of American and the Japanese people view the decision in opposite ways. In 2015, on the occasion of the seventieth anniversary of the end of World War II, the Pew Research Center carried out a joint opinion poll that found that 79 percent of Japanese said the bombing was “not justified,” while 56 percent of Americans considered it “justified.”Footnote ¹³ Japanese believe that they were already defeated and on the verge of surrender, while a majority of Americans still hold that the use of the bomb was necessary to end the war and saved massive American casualties. One of the pillars of Japan’s postwar national identity, about which virtually all Japanese (whatever their political persuasion) agree, is the belief that Japan, as the only nation to have suffered an atomic attack, has a unique mission to lead the world in banishing nuclear weapons.

In the many years that I have taught the course on the Hiroshima decision, most of my students have been Americans, but I also have had many students from other countries whose interest and approach to the Hiroshima decision are different. Japanese students have a mix of views, many feeling, as the opinion poll indicated, the bomb was unnecessary because Japan was already defeated. To Chinese and Koreans, however, the decision brought the end of the war and their suffering under Japanese imperialism. As one of my Chinese students wrote in his term paper:

The Oxford historian Rana Mitter writes that for the Chinese, as for the Americans, World War II was “a good war.”Footnote ¹⁵

Many, perhaps most, Americans have had a sense of unease about having been the only nation to use the bomb. We find it difficult to square with our belief that we are a nation of exceptional virtue and we find it painful when foreign observers remind us of the decision. In 2003, when President George W. Bush announced the invasion of Iraq, Nelson Mandela angrily questioned American self-righteousness in light of Hiroshima and Nagasaki. “Because they decided to kill innocent people in Japan, who are still suffering from that,” Mandela said, “who are they now to pretend that they are policemen of the world?”Footnote ¹⁶ A leading Israeli scholar of modern Japanese history, Ben-Ami Shillony, in a lecture on the bombing reached the harsh judgment that “Auschwitz and Hiroshima … represented a new level of atrocity that human beings can perpetrate on each other.”Footnote ¹⁷Adversaries take pleasure in emphasizing American guilt. Osama Bin Laden, mastermind of the 9/11 terrorist attack, often condemned American use of the bomb as itself a “terrorist act” that victimized “women, children, and elderly people.”Footnote ¹⁸ Russian President Vladimir Putin observed that Stalin was “a tyrant, but I very much doubt that in the spring of 1945, if he had been in possession of an atomic bomb, he would have used it against Germany.”Footnote ¹⁹

American politics have made the issue a third rail and not permitted politicians to express regret. In 1991, on the fiftieth anniversary of Pearl Harbor, reporters asked President George H. W. Bush if an American statement of regret for Hiroshima might be forthcoming if the Japanese apologized for Pearl Harbor. “Not from this president,” he replied. “I was fighting over there. … Can I empathize with a family whose child was victimized by these attacks? Absolutely. But I can also empathize with my roommate’s mother, my roommate having been killed in action.”Footnote ²⁰ In Japan, Bush’s response at once doomed the Diet’s own consideration of whether it might make an apology for Pearl Harbor. Four years later, in 1995, on the fiftieth anniversary of the Hiroshima bomb, President Bill Clinton told the American Society of Newspaper Editors that America owed Japan no apology and that President Truman had made the right decision “based on the facts he had before him.”Footnote ²¹

Barack Obama cautiously broached the issue in the first foreign policy speech of his presidency, April 5, 2009, which he devoted to the need to strengthen the Nuclear Non-proliferation Treaty. He observed that America was obligated to take the lead in ridding the world of atomic weapons because “as a nuclear power – as the only nuclear power to have used a nuclear weapon – the United States has a moral responsibility to act.” He was at once chided in a Wall Street Journal editorial for offering “a barely concealed apology for Hiroshima [which] is an insult to the memory of Harry Truman, who saved a million lives by ending World War II without a bloody invasion of Japan.”Footnote ²² In a historic gesture of reconciliation, in May 2016, Obama became the first sitting US president to visit the Hiroshima Peace Memorial. He told the Japanese press that he did not intend to offer an apology because

Presidential candidate Donald Trump at the time tweeted, “Does President Obama ever discuss the sneak attack on Pearl Harbor when he is in Japan?” and told a campaign rally that Obama’s being in Hiroshima is “fine. Just as long as he doesn’t apologize.”Footnote ²⁴

The Smithsonian Controversy

Most controversies among historians remain within the academy and attract little public notice. The Hiroshima decision is different. A great many Americans are now aware of the controversy and have an opinion. What drew mass public attention to the historical controversy was an exhibit planned by the Smithsonian’s National Air and Space Museum at the time of the fiftieth anniversary of the atomic bombing in 1995. The exhibit was to feature the refurbished Enola Gay, the B-29 that dropped the bomb on Hiroshima, with an accompanying text which would interpret the issues that the bombing raised. Planning for the event exploded in a firestorm of criticism that gained immense public attention and left a legacy of public controversy over the American use of the bomb.Footnote ²⁵

The Museum director, Martin Harwit, a Cornell astrophysicist, wanted to interpret rather than simply celebrate the event. Harwit assembled a group of his curators to write the script for the exhibition. His intention was to “tell the whole story, from the American as well as the Japanese side.”Footnote ²⁶ Harwit and his curators were convinced that “scholarly research would show using atomic bombs against Japan had been a mistake.”Footnote ²⁷ They drew advice from historians who inclined strongly to revisionist critiques of the use of the bomb, questioning the motives, morality, and casualty estimates of the decision-makers.

The slant of the curators’ text was evident in its opening statement: “For most Americans, this war was fundamentally different than the one waged against Germany and Italy – it was a war of vengeance. For most Japanese it was a war to defend their unique culture against Western imperialism.”Footnote ²⁸ An advisory board of historians suggested changes in the curators’ text, but it was too late. Given a chance to preview the text, veterans groups, with support from the media, were outraged and protested to members of Congress that the narrative was unpatriotic in its neglect of Japan’s treacherous attack that began the war, was dismissive of the suffering and sacrifices the GIs had made in the Pacific, and was oblivious to the massive American casualties that an invasion would have cost and that the bomb had prevented. Harwit asked for an internal review by a group of largely military historians who agreed the text was biased, unbalanced, and unacceptable. The script went through repeated modifications but, unlike other controversies surrounding historical commemoration such as the Vietnam Veterans Memorial Wall, a compromise could not be reached. The veterans groups demanded that the text acknowledge that there was no alternative to the use of the bomb and that a million lives had been saved.Footnote ²⁹ They took their case to Congress. The Senate passed a resolution condemning the text as offensive. The House demanded the resignation of the director, threatened to cut off funding of the Smithsonian, and announced hearings. Harwit resigned and the exhibition opened with only the forward fuselage of the Enola Gay on display and no interpretive text. When I visited the exhibit on the Mall in Washington, I found only a minimal statement explaining the bombing, a short video with recollections of the pilot and crew members of the Enola Gay, and the fuselage looming overhead.

Commenting on the controversy, a British observer wrote that “the memory of the atomic bombing of Hiroshima, and of World War II as a whole, holds a very special place in the cultural psyche of America. A notion of World War II as being a ‘Good War’ prevails in American society. An America without that heroic image is unimaginable.”Footnote ³⁰ The Stanford historian Barton Bernstein, a member of the advisory board, was dismayed by the critics and wrote that “their insistence on hewing to the ‘official’ version of the bomb story despoiled the very democratic values that were at stake in World War II” by blocking “free inquiry, dialogue, questioning, and dissent.”Footnote ³¹ Those who engage in public history as the Smithsonian curators did are taking a risk when they challenge the deeply held assumptions of national identities. In such circumstances, public history may be like “doing history without a safety net.” Harwit later ruefully reflected that “the losers in this drama were the American public.”Footnote ³² Ironically, however, this controversial exhibition did more than anything else to attract public interest to the nature of the debate over the Hiroshima decision. It was no longer simply an academic debate. It was now a public controversy.

This Book

This book took shape over many years of teaching on the Hiroshima decision. I have given public lectures on “Hiroshima and the Historians” and written several articles by the same title.Footnote ³³ In this book, I am gathering my thoughts for several purposes. First, it is a study of the anatomy of the debate among historians about an event that was central to major developments in modern history. I have to be highly selective, choosing from the voluminous writings of historians a judicious number of interpretations for scrutiny because they represent the main lines of a controversy unfolding over the last seventy-five years. The ones chosen here are works I used in my teaching.

Let me emphasize that when I refer to “the Hiroshima decision” I am also including Nagasaki. As the historian Martin Sherwin wrote: “[T]he destruction of Hiroshima and Nagasaki was the result of a single decision.”Footnote ³⁴ From the beginning of deliberations on the use of the bomb it was widely assumed that more than one would be used and that it would be left to the military to determine. The military drew up a target list of cities and when Kyoto was struck from the initial target list of cities, Nagasaki was added. Kokura was to be the second city hit by the bomb, but when the crew on Bockscar, the plane carrying the bomb, found it under the clouds, they proceeded on to the next target. Nagasaki might well have been avoided, but weather, human decision, and misfortune befell it.

The book’s second purpose is to explain the nature of the historian’s craft. Most of the writing on the nature of the historian’s craft is of a philosophical and abstract nature. What I do in this book is somewhat unusual. I want to illustrate the nature of the craft by seeing it at work on a concrete and contentious topic. The book demonstrates the many ways in which historians’ interpretations are shaped and influenced. I show how and why, despite agreement on basic facts, historians have come to multiple competing interpretations. The Hiroshima controversy teaches us a lot about how historical knowledge progresses. We learn that the clash of ideas is the means by which historians pursue truth. From the debate and contention over more than seventy-five years we have gained a deep understanding of the decision to use the bomb. But this will not be the final word.

The book’s third purpose is to show the value of historians in a free society. Authoritarian regimes go to great lengths to rewrite history to undergird their power, but democratic societies also face challenges to the writing of history. The role of a robust historical profession in a critical examination of the past is fundamental to the health of a democratic society. As the British historian John Tosh explains:

In the present day, when the foundations of democratic societies are weakened by rampant disinformation and propaganda, historians must preserve their profession as a model of integrity in the pursuit of truth.

My mentor, the American historian Ernest May, who introduced me as a student to the study of historiography, observed that professors write books for other professors. That is the path to promotion, tenure, and attention in the academic world. In a book reflecting on uses of the study of history for policymakers, he and his coauthor wrote: “Of any book written by a professor, the presumption should be that its intended audience is other professors. There are fortunately a number of exceptions, but not enough to warrant a different rule.”Footnote ³⁶ This book is one of those exceptions. It is written for a broad audience. My hope is that this book will be accessible for an informed public and especially for students interested not only in the Hiroshima decision but also in history and historiography.