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Teaching History. , home of the National History Education Clearinghouse

Historian Christopher Hamner teaches at George Mason University, serves as Editor-in-Chief of Papers of the War Department, 1784-1800, and is the author of Enduring Battle: American Soldiers in Three Wars, 1776-1945.

On August 6, 1945, after 44 months of increasingly brutal fighting in the Pacific, an American B-29 bomber loaded with a devastating new weapon appeared in the sky over Hiroshima, Japan.

With the US already angry about the drawn out Pacific War and the bombing of Pearl Harbor, this gave them enough evidence to have the thoughts of going to war with Japan. After Franklin Roosevelt died Truman became the new president, but with such short notice of the newly created Atomic Bomb, he was left with an important decision. Whether or not to use the nuclear weapon on Japan rather than invading and taking control. Both the US and Japan both have fighting spirits along with the machines and soldiers to back that up. The US government had been thinking about a safer, less costly of money and American lives, process of ending the war with Japan. They thought the best way was to use this new weapon against them since no other nations had created it before them.

Minutes later, that new weapon—a bomb that released its enormous destructive energy by splitting uranium atoms to create a chain reaction—detonated in the sky, killing some 70,000 Japanese civilians instantly and leveling the city.
At 8:15 on the morning of August 6, 1945, the first bomb was dropped on Hiroshima, nicknamed “Little Boy.” It is estimated that 140,000 died due to the bomb on Hiroshima. The Enola Gay flew over Hiroshima and dropped the first of the atomic bombs. Three days later, on the ninth of August, 1945, 70,000 others were killed due to the bomb dropped on Nagasaki, nicknamed “Fat Man.” While this may pose for attacks on the United States about how necessary these two bombs were, it may be quoted that China and South Korea feels Japan was “the aggressor, rather than the victim, of war” (Shubert). Japan played a role in its essential fate; no one in war is innocent.

Three days later, the U.S. dropped a second atomic bomb over the city of Nagasaki, with similarly devastating results. The following week, Japan’s emperor addressed his country over the radio to announce the decision to surrender.
August 6, 1945 and August 9, 1945 were days in history like no other. Only one country in history has ever used an atomic bomb against another nation; the United States of America. Code named the Manhattan Project, the atomic bombs were being developed to use against Japan towards the end of World War II. The United States was completely justified in dropping the bombs on Japan. Japan was near defeat, but many question how close Japan was to surrender (Jennings). Although some do not agree with the actions of the United States, the bombs were dropped, altering the history of World War II, our country, and the rest of the world.

World War II had finally come to its dramatic conclusion.

The decision to employ atomic weapons against Japan remains a controversial chapter in American history. Even before the new President Harry S. Truman finalized his decision to use the bombs, members of the President’s inner circle grappled with the specifics of the decision to drop the new weapon.

America didn't like the idea of losing lives. The conflict between them started when Roosevelt was Alive and ended after he died while Truman was in charge. Truman was the one who ended the conflict by dropping the Atomic bomb in a message, to tell them they are in charge and have the power. All the reasons played their unique part in the dropping of the bomb. However there were key factors in the dropping of the bomb, firstly was to scare them off and stop the spreading of communism. Secondly was to get even with Japan for them attacking Pearl Harbour. Thirdly was bad attitude towards P.O.W. There were consequences to the dropping of the bomb, some were babies were being born with physical defects. The next few years following the bombs being dropped, people were still dieing of radiation sickness and cancer, Innocent civilians were killed or were dying. People may question if dropping the bomb on Japan was needed to defeat them. In my opinion I think they had all authority to attack back because they were attacked by Japan and would have felt provoked with Japan testing their power. ?? ?? ?? ?? 1 more.

Their concerns revolved around a cluster of related issues: whether the use of the technology was necessary to defeat an already crippled Japan; whether a similar outcome could be effected without using the bomb against civilian targets; whether the detonation of a second bomb days after the first, before Japan had time to formulate its response, was justified; and what effect the demonstration of the bomb’s devastating power would have on postwar diplomacy, particularly on America’s uneasy wartime alliance with the Soviet Union.
This reason may not be a key factor to the dropping of the bomb, because if they won the war all that was lost would be gained again. America's aim was to create the most powerful bomb in history this was called the Manhattan project it was secretly being done. Technological reasons were very important in the decision made to drop the bomb. Scientists aimed to see if the bomb would actually work under the spot light. They had paid $2 billon for the bomb to be made and so many scientists were involved in creating the first atomic bomb they would expect it to be very power and convincing in a battle. They sent data back to America after collecting it from the bomb nicknamed 'Fatman' they did this because they wanted to find out more information about the bomb and its attributes also how could they improve it. Military reasons may have played a role in the dropping of the bomb. The Bomb might have been dropped in a test because as this was the first Atomic bomb they would have wanted to know if it works and does the job, they could use them instead of wasting lives in battles. more.

Controversy is Alive and Well

The ongoing struggle to present the history of the atomic bombings in a balanced and accurate manner is an interesting story in its own right, and one that has occasionally generated an enormous amount of controversy.

No one may be sure about how many American lives - or even Japanese lives - the atomic bombs saved. There is no way to fathom such a number. However, there is a way to fathom time, and saving time in war does result in saving lives. An invasion on Japan was being planned for the following year, leaving a plethora of time for which American and Japanese lives may have been taken in war. However, the invasion was not necessary for on September 2, 1945 - less than a month after the first atomic bomb was dropped, Japan officially signed to unconditional surrender. The dropping of the atom bomb served its purpose - to end the war as quickly as possible with the least amount of American deaths as possible. We had the bomb, which saved multiple men’s lives; men who would have eventually had to invade Japan, resulting in the deaths of both Japanese men and American men (Siegel).

In 1995, anticipating the 50th anniversary of the end of World War II, the Smithsonian’s National Air and Space Museum planned a display around the fuselage of the Enola Gay, the aircraft that dropped the first bomb, for its museum on the National Mall.
Yes, the Japanese military did bomb Pearl Harbor when the U.S. was not involved in the war. And yes, the U.S. did have the right to fight back, but not like it did. The U.S. might have wanted to give Japan a taste of its own medicine, but it shouldn’t have overdosed the Japanese. The U.S. is a Christian nation, and Japan practices Buddhism. In the Christian Bible, it says “An eye for an eye; and a tooth for a tooth”, but Buddha disagrees with that and stated “An eye for an eye just makes the whole world blind” I might be Roman Catholic, but I strongly agree with the words of Buddha.

That exhibit would place the invention of atomic weapons and the decision to use them against civilian targets in the context of World War II and the Cold War, provoking broader questions about the morality of strategic bombing and nuclear arms in general.
Additionally, it may be argued that “what was new about these bombs was the technology, not the morality” (Sowell). A huge part of war is death, whether it occur due to shootings or bombs or other means of war. Death is death, regardless of how it happens. Technological advancements will call for new means of death, and as long as a country is in war, it is subjecting their people to death, by all means. Would the vast number of deaths be as greatly questioned if they had occurred due to anything but atomic bombs? The atomic bombs were strong military weapons of the war (Siegel). “Morality is about what you do to people, not the technology you use” (Sowell).

The ongoing struggle to present the history of the atomic bombings in a balanced and accurate manner is an interesting story in its own right. . . .

The design for the exhibit quickly triggered an avalanche of controversy.

Shubert, Atika. “Hiroshima Still Stokes Controversy” CNN. 05 August 2005. 19 January 2009.

Critics charged that it offered a too-sympathetic portrayal of the Japanese enemy, and that its focus on the children and elderly victims of the bombings at Hiroshima and Nagasaki encouraged visitors to question the necessity and morality of the weapons.
Desperate times call for desperate measures, and war is definitely no exception to this statement. Just as the attack on Pearl Harbor was a tragic day in our history, the days of the atomic bombs in Hiroshima and Nagasaki are tragic for Japan. However, as quoted by a Japanese survivor of the atomic bombs, Mrs. Hatsuyo Nakamura, “it was war and we had to expect it.” A country only enters war to defend their country and win, by any means necessary. The actions of war are unavoidable and cannot be helped, as stated by the Japanese expression “shikata ga nai” (Hersey 89). Pearl Harbor was bombed by the Japanese because they felt that was the best way to make advancements in the war. The United States used the bombs to dictate the terms of the surrender of the Japanese dictatorship, and essentially the Japanese surrender. The atomic bombs were used by the United States because it was thought to be the best way to make advancements with the Japanese.

As originally written, those critics alleged, the exhibit forwarded an anti-American interpretation of events surrounding the bombs’ use. That such a message was to appear in a national museum amplified the frustrations of critics (especially veterans’ groups), who believed that the exhibit should not lead museumgoers to question the decision to drop the bomb or to portray the Pacific war in morally neutral terms.

In place of the original exhibit, veterans’ organizations offered a replacement exhibit with a very different message. Their proposed exhibit portrayed the development of the atomic weapons as a triumph of American technical ingenuity, and the use of both bombs as an act that saved lives—the lives of American soldiers who would otherwise have had to invade the Japanese home islands, and the lives of thousands of Japanese who would, it was assumed, have fought and died with fanatic determination opposing such an invasion.

In war, you want the least amount of people to die from your country. In war, you want your country to win. A country will do whatever they need to do to make those two statements a reality. For the United States of America, dropping the two atomic bombs on Hiroshima and Nagasaki was the way. War is not ideal, so no situation in war will ever be ideal. You must do what you need to do. The United States was justified in dropping the atomic bombs on Japan. What would our country be if we would have held back and not used the technology we had developed? No one knows, because the United States dropped the atomic bombs, which accomplished the ultimate goal in war; victory.

The revised exhibit removed the questioning tone of the original, replacing it with more certainty: the use of the bombs, it argued, was both necessary and justified.

When the controversy died down, the Smithsonian elected not to stage any exhibit of the aircraft fuselage.

The historians who produced the original exhibit stood accused of historical revisionism by their critics, of needlessly complicating patriotic consensus with moral concerns.

Siegel, Allen. Lifting the Fog The Bombing of Hiroshima and Nagasaki. Maljack Productions, Inc. MPI Home Video, 1992.

The fallout from the controversy led to loud, public debate in the halls of Congress and, ultimately, to the resignation of several leaders at the museum. When the controversy died down, the Smithsonian elected not to stage any exhibit of the aircraft fuselage. Years later, the plane went on display at the Smithsonian’s Udvar-Hazy Center outside Washington, DC, where it resides now, accompanied by a brief placard detailing its technical specifications.

The Textbook Approach

Because the use of the atomic weapons evokes such passionate responses from Americans—from those who believe that the use of the bombs was wholly justified to those who believe that their use was criminal, and the many people who fall somewhere in between—it is a particularly difficult topic for textbooks to discuss.

The United States was wrong to drop the Atomic Bomb on Japan. The U.S sunk to shocking extremes to make sure that Japan would surrender. The bombs were dropped on two harmless Japanese cities. According to various sources, Japan would have surrendered even if the bombs were not dropped.

In order to avoid a potentially treacherous debate, textbooks have often adopted a set of compromises that describe the end of the war but avoid or omit some of the most difficult parts of the conversation.

A 1947 history textbook, produced just two years after the bombings did just this, sidestepping the controversy by presenting the story at a distance and refraining from interpretation or discussion of civilian casualties: “The United States unveiled its newest weapon, demonstrating twice—first at Hiroshima and then at Nagasaki—that a good-sized city could almost be erased from the map in one blinding flash.

In other words and my own opinion, dropping the atomic bomb on Hiroshima and Nagasaki were in the end a good decision. It did kill a lot of people but also saved many from starving and being drafted into the war. If we did not go through with the mission, we would have entered a war neither side was prepared for and dragged out the Pacific War longer too.

Confronted by this combination of forces, Japan surrendered August 14.”

“If the war dragged on and Americans had to invade Japan, it might cost a million lives…life for life, the odds were that [the atomic bomb] would cost less.”

Later textbooks made other compromises. The 2005 textbook A History of the United States adopts a familiar tone, arguing that President Truman based his decision to drop the bomb mainly on a complex calculus of the cost in human lives if the war were to continue: “Should the United States use the atomic bomb? No one knew how long Japan would hold out.

Sowell, Thomas. “The Morality of Dropping the Atomic Bomb on Hiroshima and Nagasaki.” Capitalism Magazine. 09 August 2005. 19 January 2009. <

” That uncertainty forced American planners to assume the worst: “If the war dragged on and Americans had to invade Japan, it might cost a million lives. The atomic bomb, President Truman knew, might kill many thousands of innocent Japanese.
To give you an idea of just how badly Japan is affected by this problem here are the figures for imported energies such as gas and oil: Oil 99.7% imported, Coal 99.8% imported, Copper 98.7% imported, Iron Ore 99.8% imported and Timber 75% imported from abroad.

But life for life, the odds were that it would cost less.”

A 2006 textbook, The Americans, suggests that the decision to drop the bomb occurred largely outside moral concerns: “Should the Allies use the bomb to bring an end to the war? Truman did not hesitate. On July 25, 1945, he ordered the military to make final plans for dropping two atomic bombs on Japan.” The paragraph on the decision concludes with a compelling quote from the President himself: “Let there be no mistake about it. I regarded the bomb as a military weapon and never had any doubt it should be used.”

Other recent textbooks have labored to present this often-contentious topic in a more nuanced manner. The 2007 textbook American Anthem describes the decision-making process as an involved one, observing “Truman formed a group to advise him about using the bomb. This group debated where the bomb should be used and whether the Japanese should be warned. After carefully considering all the options, Truman decided to drop the bomb on a Japanese city. There would be no warning." The carefully written passage does not suggest that the question of whether to use the bomb against civilian targets was part of the debate; it describes the inquiry as focused on where to drop the bomb and whether a warning would precede its use.

More recent textbooks often offer viewpoints from other perspectives—including Japanese civilians, who suffered the legacy of atomic fallout for decades after the original explosion—from a morally neutral stance, inviting (or directly asking) readers to make their own judgments. Besides offering a description of Truman’s decision-making process, the American Anthem textbook includes a passage of equivalent length that describes the destruction on the ground, anchored by a quote from a survivor of the Hiroshima bomb. It also features a “Counterpoints” section that contrasts a quote from Secretary of War Henry Stimson supporting the bomb’s use with one from Leo Szilard, an atomic physicist, characterizing the use of the bombs against Japan as “one of the greatest blunders of history.

This student written piece of work is one of many that can be found in our AS and A Level International History, 1945-1991 section.

What the Documents Reveal

A discussion that focuses primarily on the need to employ the bomb in order to save lives—the lives of Japanese civilians as well as those of American soldiers—is incomplete. In fact, as the documentary record shows, there was a good deal of debate over the use of the weapons during the summer of 1945, much of which focused on more complex issues than the lives that would be saved or lost in ending the war.

A discussion that focuses primarily on the need to employ the bomb in order to save lives—the lives of Japanese civilians as well as those of American soldiers—is incomplete.

Dwight D. Eisenhower, the Supreme Commander of the Allied forces in Europe and one of the architects of the successful campaign against Germany, was one of the dissenters. After the war, Eisenhower recalled his position in 1945, asserting that “Japan was defeated and… dropping the bomb was completely unnecessary.” Eisenhower’s objection was, in part, a moral one; as he noted, “I thought our country should avoid shocking world opinion by the use of a weapon whose employment was, I thought, no longer mandatory as a measure to save American lives. It was my belief that Japan was, at that very moment, seeking some way to surrender with a minimum loss of 'face.'" Eisenhower recalled that his objection found an unreceptive audience with Secretary of War Henry Stimson. In Eisenhower's own words, Stimson was “deeply perturbed by my attitude, almost angrily refuting the reasons I gave for my quick conclusions.” (In a separate document, Stimson himself concurred with Eisenhower’s conclusion that there was little active American attempt to respond to Japan’s peace feelers to prevent the use of the atomic weapons: “No effort was made, and none was seriously considered, to achieve surrender merely in order not to have to use the bomb”)

The year after the Japanese surrender, the U.S. government released its own Strategic Bombing Survey, an effort to assess the effectiveness of dropping bombs on civilian populations, including the firebombs used in Europe and the Pacific, and the atomic weapons detonated over Hiroshima and Tokyo (see Primary Source US. Strategic Bombing Survey [1946]). Its findings suggested that the bombs were largely superfluous, and that Japan’s surrender was all but guaranteed even without the threat of invasion. “Based on a detailed investigation of all the facts,” the SBS concluded, “and supported by the testimony of the surviving Japanese leaders involved, it is the Survey's opinion that . . . Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.” Though firm in its assertions, the SBS received widespread criticism from many quarters for drawing conclusions far beyond the available evidence. (Many critics noted, rightly, that the SBS was itself hardly a disinterested document, since it was produced by an organization with an interest in emphasizing the effectiveness of conventional airpower)

The compromises 21st-century textbooks have struck appear understandable if not necessary.

The Strategic Bombing Survey’s conclusions highlight another important factor in the decision to employ the bombs against Japan: the message such a display would send to Josef Stalin. Uneasy allies in the war against Germany, Russian forces joined the war in Japan in August 1945. Contemporary observers noted that the demonstration of the deadly new weapon’s considerable might had the additional effect of warning Stalin that the U.S. would exercise considerable power in the postwar period. Furthermore, dropping two bombs only days apart had the added benefit of convincing the Russians that the U.S. possessed a formidable supply of the new weapons; when in fact, the U.S. nuclear arsenal was entirely depleted after the two attacks on Japan.

A survey of primary sources from the summer of 1945 and the months afterward reveals a variety of opinions, arguments, and justifications regarding the use of atomic weapons. Embracing the variety of opinions while also presenting a narrative that depicts the decision and its effects from multiple perspectives is a near-impossible task. Given how controversial the story of Hiroshima and Nagasaki has proved to be, the compromises 21st-century textbooks have struck appear understandable if not necessary.

Leo Szilard's Petition to the President (1945)


Leo Szilard was one of the first physicists to identify the military application of atomic power. In fact, Szilard wrote most of the famous 1939 letter from Albert Einstein to then-President Franklin Delano Roosevelt outlining the potential of such a bomb and the fears that Hitler’s Germany was currently working to develop one that helped set the American Manhattan Project in motion. As the atomic tests reached their successful conclusion, however, Szilard raised serious concerns about the practical use of such weapons against civilian targets.

In July 1945, he circulated a petition among the scientists who had worked on the bomb’s construction in an effort to discourage the President from employing it. Sixty-eight scientists signed the petition, which did not reject the use of the weapon wholesale but referred to the potential of a postwar atomic arms race which might have catastrophic consequences for the U.S. “The atomic bombs at our disposal,” the petition noted, “represent only the first step in this direction”; there would be “almost no limit to the destructive power which will become available” as scientists refined the technology. Thus their use to end World War II might serve as a disastrous example in the future: “the nation which sets the precedent of using these newly liberated forces of nature for purposes of destruction may have to bear the responsibility of opening the door to an era of devastation on an unimaginable scale.”

Primary Source(s)

A Petition to the President of the United States

Discoveries of which the people of the United States are not aware may affect the welfare of this nation in the near future. The liberation of atomic power which has been achieved places atomic bombs in the hands of the Army. It places in your hands, as Commander-in-Chief, the fateful decision whether or not to sanction the use of such bombs in the present phase of the war against Japan.

We, the undersigned scientists, have been working in the field of atomic power. Until recently, we have had to fear that the United States might be attacked by atomic bombs during this war and that her only defense might lie in a counterattack by the same means. Today, with the defeat of Germany, this danger is averted and we feel impelled to say what follows:

The war has to be brought speedily to a successful conclusion and attacks by atomic bombs may very well be an effective method of warfare. We feel, however, that such attacks on Japan could not be justified, at least not unless the terms which will be imposed after the war on Japan were made public in detail and Japan were given an opportunity to surrender.

If such public announcement gave assurance to the Japanese that they could look forward to a life devoted to peaceful pursuits in their homeland and if Japan still refused to surrender our nation might then, in certain circumstances, find itself forced to resort to the use of atomic bombs. Such a step, however, ought not to be made at any time without seriously considering the moral responsibilities which are involved.

The development of atomic power will provide the nations with new means of destruction. The atomic bombs at our disposal represent only the first step in this direction, and there is almost no limit to the destructive power which will become available in the course of their future development. Thus a nation which sets the precedent of using these newly liberated forces of nature for purposes of destruction may have to bear the responsibility of opening the door to an era of devastation on an unimaginable scale.

If after this war a situation is allowed to develop in the world which permits rival powers to be in uncontrolled possession of these new means of destruction, the cities of the United States as well as the cities of other nations will be in continuous danger of sudden annihilation. All the resources of the United States, moral and material, may have to be mobilized to prevent the advent of such a world situation. Its prevention is at present the solemn responsibility of the United States—singled out by virtue of her lead in the field of atomic power.

The added material strength which this lead gives to the United States brings with it the obligation of restraint and if we were to violate this obligation our moral position would be weakened in the eyes of the world and in our own eyes. It would then be more difficult for us to live up to our responsibility of bringing the unloosened forces of destruction under control.

In view of the foregoing, we, the undersigned, respectfully petition: first, that you exercise your power as Commander-in-Chief, to rule that the United States shall not resort to the use of atomic bombs in this war unless the terms which will be imposed upon Japan have been made public in detail and Japan knowing these terms has refused to surrender; second, that in such an event the question whether or not to use atomic bombs be decided by you in light of the considerations presented in this petition as well as all the other moral responsibilities which are involved.


Just two weeks after the successful test of the first atomic device in the New Mexico desert, Secretary of War Henry Stimson delivered versions of the statement to be issued in the event that the U.S. elected to use the weapon against Japan. The memo begins by noting the orders-of-magnitude increase in the destructive power of the first atomic weapon, a power the statement notes is achieved by harnessing the “basic power of the universe.” In several passages, the statement emphasizes the bomb’s role as a tool of retribution, noting that “the Japanese began the war from the air at Pearl Harbor,” and that “they have been repaid many fold.” It emphasizes the legitimacy of using the new technology of atomic weaponry against Japan by stressing the fact of Japanese aggression: "The force from which the sun draws its power has been loosed against those who brought war to the Far East."

Primary Source(s)

[Cover Letter]
July 31, 1945.
Dear Mr. President:
Attached are two copies of the revised statement which has been prepared for release by you as soon as the new weapon is used. This is the statement about which I cabled you last night.

The reason for the haste is that I was informed only yesterday that, weather permitting, it is likely that the weapon will be used as early as August 1st, Pacific Ocean Time, which as you know is a good many hours ahead of Washington time.

This message and inclosure are being brought to you by Lt. R. G. Arneson, whom Secretary Byrnes will recognize as the Secretary of the Interim Committee, appointed with your approval, to study various features of the development and use of the atomic bomb.

Faithfully yours,
Henry L. Stimson
Secretary of War.
The Honorable
The President.

[Document Pages 1-6]

Draft of 30 July 1945.

______________________hours ago an American airplane dropped one bomb on _______________________ and destroyed it usefulness to the enemy. That bomb has more power than 20,000 tons of T.N.T. It has more than two thousand times the blast power of the British "Grand Slam" which is the largest bomb ever yet used in the history of warfare.

The Japanese began the war from the air at Pearl Harbor. They have been repaid many fold. And the end is not yet. With this bomb we have now added a new and revolutionary increase in destruction to supplement the growing power of our armed forces. In their present form these bombs are now in production and even more powerful forms are in development.

It is an atomic bomb. It is a harnessing of the basic power of the universe. The force from which the sun draws its power has been loosed against those who brought war to the Far East.

Before 1939, it was the accepted belief of scientists that it was theoretically possible to release atomic energy. But no one knew any practical method of doing it. By 1942, however, we knew that the Germans were working feverishly to find a way to add atomic energy to the other engines of war with which they hoped to enslave the world. But they failed. We may be grateful to Providence that the Germans got the V-1's and the V-2's late and in limited quantities and even more grateful that they did not get the atomic bomb at all.

The battle of the laboratories held fateful risks for us as well as the battles of the air, land and sea, and we have now won the battle of the laboratories as we have won the other battles.

Beginning in 1940, before Pearl Harbor, scientific knowledge useful in war was pooled between the United States and Great Britain, and many priceless helps to our victories have come from that arrangement. Under that general policy the research on the atomic bomb was begun. With American and British scientists working together we entered the race of discovery against the Germans.

The United States had available the large number of scientists of distinction in the many needed areas of knowledge. It had the tremendous industrial and financial resources necessary for the project and they could be devoted to it without undue impairment of other vital war work. In the United States the laboratory work and the production plants, on which a substantial start had already been made, would be out of reach of enemy bombing, while at that time Britain was exposed to constant air attack and was still threatened with the possibility of invasion. For these reasons Prime Minister Churchill and President Roosevelt agreed that it was wise to carry on the project here. We now have two great plants and many lesser works devoted to the production of atomic power. Employment during peak construction numbered 125,000 and over 65,000 individuals are even now engaged in operating the plants. Many have worked there for two and a half years. Few know what they have been producing. They see great quantities of material going in and they see nothing coming out of these plants, for the physical size of the explosive charge is exceedingly small. We have spent two billion dollars on the greatest scientific gamble in history—and won.

But the greatest marvel is not the size of the enterprise, its secrecy, nor its cost, but the achievement of scientific brains in putting together infinitely complex pieces of knowledge held by many men in different fields of science into a workable plan. And hardly less marvellous has been the capacity of industry to design, and of labor to operate, the machines and methods to do things never done before so that the brain child of many minds came forth in physical shape and performed as it was supposed to do. Both science and industry worked under the direction of the United States Army, which achieved a unique success in managing so diverse a problem in the advancement of knowledge in an amazingly short time. It is doubtful if such another combination could be got together in the world. What has been done is the greatest achievement of organized science in history. It was done under high pressure and without failure.

We are now prepared to obliterate more rapidly and completely every productive enterprise the Japanese have above ground in any city. We shall destroy their docks, their factories, and their communications. Let there be no mistake; we shall completely destroy Japan's power to make war.

It was to spare the Japanese people from utter destruction that the ultimatum of July 26 was issued at Potsdam. Their leaders promptly rejected that ultimatum. If they do not now accept our terms they may expect a rain of ruin from the air, the like of which has never been seen on this earth. Behind this air attack will follow sea and land forces in such numbers and power as they have not yet seen and with the fighting skill of which they are already well aware.

The Secretary of War, who has kept in personal touch with all phases of the project, will immediately make public a statement giving further details.

His statement will give facts concerning the sites at Oak Ridge near Knoxville, Tennessee, and at Richland near Pasco, Washington, and an installation near Santa Fe, New Mexico. Although the workers at the sites have been making materials to be used in producing the greatest destructive force in history they have not themselves been in danger beyond that of many other occupations, for the utmost care has been taken of their safety. A scientific report of the project will be made public tomorrow.

The fact that we can release atomic energy ushers in a new era in man's understanding of nature's forces. Atomic energy may in the future supplement the power that now comes from coal, oil, and falling water, but at present it cannot be produced on a basis to compete with them commercially. Before that comes there must be a long period of intensive research.

It has never been the habit of the scientists of this country or the policy of this Government to withhold from the world scientific knowledge. Normally, therefore, everything about the work with atomic energy would be made public.

But under present circumstances it is not intended to divulge the technical processes of production or all the military applications, pending further examination of possible methods of protecting us and the rest of the world from the danger of sudden destruction.

I shall recommend that the Congress of the United States consider promptly the establishment of an appropriate commission to control the production and use of atomic power within the United States. I shall give further consideration and make further recommendations to the Congress as to how atomic power can become a powerful and forceful influence towards the maintenance of world peace.



  1. Page 3, line 2, suggest adding "whereas at that time Britain was exposed to constant air attack and was still threatened with the possibility of invasion."
  2. Page 6, line 6, for the words "unless or until some method of control can be devised that will protect us" suggest "pending further examination of possible methods of protecting us."

Hours after the Hiroshima bombing, American bombers again took to the skies over Japan. This time their payloads contained not bombs but leaflets: printed warnings in Japanese cautioning those on the ground of the fearful new weapon the U.S. had deployed. Addressed to “The People of Japan,” it notified them that the United States possessed “the most destructive explosive ever devised by man,” a single one of which carried the equivalent of 2,000 bomb loads of explosive power. That “awful fact,” the leaflet read, “is one for you to ponder and we solemnly assure you it is grimly accurate.” The leaflet also indicated that the weapon had already been used once in Japan: “If you still have any doubt, make inquiry as to what happened to Hiroshima when just one atomic bomb fell on that city.” It closed by urging readers to demand a quick and peaceful end to hostilities lest the U.S. employ “this bomb and all our other superior weapons to promptly and forcefully end the war.”

Such warnings to civilian populations were not unusual during the World War II. Besides offering some moral cover to the attackers, warning leaflets had other, more practical value. They sowed fear and mistrust for the government on the ground, which was often seen as unable to provide basic air defense; and by encouraging citizens to flee the cities (the leaflet dropped on Japanese civilians after Hiroshima listed not just Nagasaki but a half-dozen other potential targets) they created enormous logistical and production challenges for the target nation: civilians fleeing urban areas clogged roads and were, by definition, not working in war industries.

Primary Source(s)

[Leaflet Translation]


America asks that you take immediate heed of what we say on this leaflet.

We are in possession of the most destructive explosive ever devised by man. A single one of our newly developed atomic bombs is actually the equivalent in explosive power to what 2,000 of our giant B-29's can carry on a single mission. This awful fact is one for you to ponder and we solemnly assure you it is grimly accurate.

We have just begun to use this weapon against your homeland. If you still have any doubt, make inquiry as to what happened to Hiroshima when just one atomic bomb fell on that city.

Before using this bomb to destroy every resource of the military by which they are prolonging this useless war, we ask that you now petition the Emperor to end the war. Our President has outlined for you the thirteen consequences of an honorable surrender: We urge that you accept these consequences and begin the work of building a new, better, and peace-loving Japan.

You should take steps now to cease military resistance. Otherwise, we shall resolutely employ this bomb and all our other superior weapons to promptly and forcefully end the war.



HyperWar: A Hypertext History of the Second World War. Leaflet AB-11, August 16, 1945. Accessed March 2, 2012.

U.S. Strategic Bombing Survey (1946)


After the war, Secretary of War Henry Stimson commissioned a set of studies to assess the effectiveness of its strategic bombing campaigns—that is, the use of aircraft to drop bombs on civilian and industrial targets rather than on purely military objectives—in both Europe and the Pacific. More than 1,000 people participated in the data collection, analysis, and conclusions, which ran to more than 300 volumes. At a time when a great deal of debate surrounded the use of air power in wartime, the Strategic Bombing Survey’s findings that the air campaigns had a decisive effect on Allied victory (principally by disrupting German war production) provided important encouragement for those seeking to establish the Air Force as an independent service and to increase the emphasis on air power in future military planning.

While generally favorable regarding the contributions of strategic bombing to overall victory, the Strategic Bombing Survey was less enthusiastic about the impact of the atomic weapons. Indeed, its passages on the Hiroshima and Nagasaki attacks concluded that “based on a detailed investigation of all the facts, and supported by the testimony of the surviving Japanese leaders involved, it is the Survey's opinion that certainly prior to 31 December 1945, and in all probability prior to 1 November 1945, Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.” That finding assumed that the conventional bombing campaign against Japan (mainly using firebombs against cities) would have continued. The SBS findings did not settle the controversy, however, and a number of later historians charged the Survey with drawing conclusions beyond what the available evidence could support.

Primary Source(s)

Excerpt from U.S. Strategic Bombing Survey:
The Survey's complement provided for 300 civilians, 350 officers, and 500 enlisted men. The military segment of the organization was drawn from the Army to the extent of 60 per cent, and from the Navy to the extent of 40 per cent. Both the Army and the Navy gave the Survey all possible assistance in furnishing men, supplies, transport and information. The Survey operated from headquarters established in Tokyo early in September, 1945 with sub-headquarters in Nagoya, Osaka, Hiroshima and Nagasaki, and with mobile teams operating in other parts of Japan, the islands of the Pacific, and the Asiatic mainland.

It was possible to reconstruct much of wartime Japanese military planning and execution engagement by engagement and campaign by Campaign, and to secure reasonably accurate statistics on Japan's economy and war-production plant by plant, and industry by industry. In addition, studies were conducted on Japan's overall strategic plans and the background of her entry into the war, the internal discussions and negotiations leading to her acceptance of unconditional surrender, the course of health and morale among the civilian population, the effectiveness of the Japanese civilian defense organization, and the effects of the atomic bombs. Separate reports will be issued covering each phase of the study. . . .

There is little point in attempting more precisely to impute Japan’s unconditional surrender to any one of the numerous causes which jointly and cumulatively were responsible for Japan’s disaster. Concerning the absoluteness of her defeat there can be no doubt. The time lapse between military impotence and political acceptance of the inevitable might have been shorter had the political structure of Japan permitted a more rapid and decisive determination of national policies. It seems clear, however, that air supremacy and its exploitation over Japan proper was the major factor which determined the timing of Japan’s surrender and obviated any need for invasion.

Based on a detailed investigation of all the facts and supported by the testimony of the surviving Japanese leaders involved, it is the Survey’s opinion that certainly prior to 31 December 1945, and in all probability prior to 1 November 1945, Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.


Harry S. Truman Library and Museum. U.S. Strategic Bombing Survey. "Japan's Struggle to End the War." Washington, DC: U.S. Government Printing Office, 1946. Accessed March 2, 2012.

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