Skip to Main Content

Oppenheimer and the Atomic Bomb


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

We are in possession of the most destructive explosion ever devised by man. A single one of our newly developed atomic bombs is actually the equivalent in explosive power to what 2000 of our giant B-29s 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.


Because your military leaders have rejected the thirteen part surrender declaration, two momentous events have occurred in the last few days.

The Soviet Union, because of this rejection on the part of the military has notified your Ambassador Sato that it has declared war on your nation. Thus, all powerful countries of the world are now at war with you.

Also, because of your leaders' refusal to accept the surrender declaration that would enable Japan to honorably end this useless war, we have employed our atomic bomb.

A single one of our newly developed atomic bombs is actually the equivalent in explosive power to what 2000 of our giant B-29s could have carried on a single mission. Radio Tokyo has told you that with the first use of this weapon of total destruction, Hiroshima was virtually destroyed.

Before we use this bomb again and again to destroy every resource of the military by which they are prolonging this useless war, petition the emperor now 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.

Act at once or we shall resolutely employ this bomb and all our other superior weapons to promptly and forcefully end the war.


Source: Harry S. Truman Library, Miscellaneous historical document file, no. 258.


Statement by the President Announcing the Use of the A-Bomb at Hiroshima
August 6, 1945

SIXTEEN HOURS AGO an American airplane dropped one bomb on Hiroshima, an important Japanese Army base. That bomb had more power than 20,000 tons of T.N.T. It had 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 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 marvelous 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.

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.

NOTE: This statement was released in Washington. It was drafted before the President left Germany, and Secretary of War Stimson was authorized to release it when the bomb was delivered. On August 6, while returning from the Potsdam Conference aboard the U.S.S. Augusta, the President was handed a message from Secretary Stimson informing him that the bomb had been dropped at 7:15 p.m. on August 5.
Harry S. Truman Library & Museum

Call for Unconditional Surrender of Japan

Statement by the President Calling for Unconditional Surrender of Japan
May 8, 1945

NAZI GERMANY has been defeated.

The Japanese people have felt the weight of our land, air and naval attacks. So long as their leaders and the armed forces continue the war the striking power and intensity of our blows
will steadily increase and will bring utter destruction to Japan's industrial war production, to its
shipping, and to everything that supports its military activity.

The longer the war lasts, the greater will be the suffering and hardships which the people of
Japan will undergo--all in vain. Our blows will not cease until the Japanese military and naval
forces lay down their arms in unconditional surrender.

Just what does the unconditional surrender of the armed forces mean for the Japanese people ?

It means the end of the war.

It means the termination of the influence of the military leaders who have brought Japan to the
present brink of disaster.

It means provision for the return of soldiers and sailors to their families, their farms, their jobs.

It means not prolonging the present agony and suffering of the Japanese in the vain hope of

Unconditional surrender does not mean the extermination or slavement of the Japanese people.

Harry S. Truman Library Museum

The War is Over

Statement by the President on the Termination of the State of War With Japan
April 28, 1952

WITH THE deposit of the United States ratification which brings into force the Treaty of Peace with Japan, the state of war has been terminated and Japan has been restored to a status of sovereign equality in the society of free peoples. This great event is especially gratifying to the Government and people of the United States who have worked in close association with the Government and people of Japan for its restoration as a prosperous and progressive nation. This common effort has strengthened the essential bonds of friendship between our two peoples.

The Treaty of Peace terminates the Allied occupation of Japan and with it the entire regime of control and opens a new era in Japan's history. During the past 6 years, the Japanese people and Government have worked to build a democratic and peace-loving nation with a sincerity and earnestness that has won them the respect of the world. The Treaty of Peace affords Japan an opportunity to make a great contribution to world peace and progress.

Japan takes her rightful place of equality and honor among the free nations of the world at a time when Communist imperialism, having already enslaved large areas and many unfortunate peoples, is seeking to extend its system of tyranny and exploitation by direct and indirect aggression. We are confident that the people of Japan are alert to this danger and are ready and willing to play their full part in meeting the common menace. For their part, the American people will continue to work with the people of Japan to promote peace and security in accordance with the purposes and principles of the United Nations Charter. To this end, simultaneously with the coming into effect of the Treaty of Peace, the United States has exchanged ratifications with Japan, and thus also brought into concurrent effect, the Security Treaty between the United States of America and Japan.

NOTE: On the same day, the President signed Proclamation 2974 "Termination of the National Emergencies Proclaimed on September 8, 1939, and May 27, 1941" (3 CFR, 1949-1953 Comp., p. 158).
See also Item 95.

Harry S. Truman Library Museums

Treaty of Peace

Statement by the President Upon Signing the Treaty of Peace With Japan and Related Security Pacts
AS PRESIDENT of the United States, it gives me great satisfaction to sign, and thus ratify today the Treaty of Peace with Japan, the Security Treaty with Australia and New Zealand, the Security Treaty with Japan, and the Mutual Defense Treaty with the Republic of the Philippines. The signing of these documents completes another in the series of steps being taken by free nations to bring peace and security to the Pacific.

When the United States and at least two more of the countries mentioned in Article 23 of the Treaty of Peace with Japan and the United States have deposited their ratifications, the historic ceremonies of restoring Japan to a position of independence, honor, and equality in the world community which began at San Francisco last September will have been brought to a conclusion. The related security and mutual defense treaties will become effective when their ratifications are either deposited or exchanged in accordance with their respective terms.

In signing these documents, I know that I express the essential unity and will of the American people for the earliest possible achievement of lasting peace and freedom with security. The Treaty of Peace with Japan and the related security and mutual defense treaties, when they go into effect, will bring that goal nearer to realization.

NOTE: The Treaty of Peace with Japan and the related security pacts were favorably considered by the Senate on March 20, 1952. The text of the treaties is printed in United States Treaties and Other International Agreements.

The Multilateral Treaty of Peace with Japan (3 UST 3169) and the Security Treaty between the United States and Japan (3 UST 3329) entered into force on April 28, 1952, and were proclaimed by the President on the same day. The Multilateral Security Treaty between Australia, New Zealand, and the United States (3 UST 3420) entered into force on April 29, 1952, and was proclaimed by the President on May 9, 1952. The Mutual Defense Treaty between the United States and the Republic of the Philippines (3 UST 3947) entered into force on August 27, 1952, and was proclaimed by the President on September 15, 1952.
See also Item 111.

Harry S. Truman Library Museum

Content created by TCC Libraries is licensed as CC BY 4.0