Manhatten Project

J. Robert Oppenheimer to James B. Conant

To James B. Conant

Berkeley
November 30, 1942

Dear Dr. Conant:

Your letter reached me with some delay since I returned to Berkeley only a day or so ago. I should like to answer first your P.S. You are quite right that the purities listed in Groves' compulsory memo are a little misleading. The reason for this is that Groves defined a satisfactory bomb as one that had a 50 per cent chance of exceeding a 1,000-ton TNT equivalent. The absolute requirements are figured on this basis. It is, of course, my opinion that we should be wanton to strive for such a low goal, but I believe that some good was in fact done by indicating at that time that the purity requirements are not fantastic. The desirable requirements are equally undefined since the purer the material (up to a purity of about 100-fold that given) the less must we be worried about getting the maximum speed for the firing mechanism of the detonator; and this will make for simplicity and reliability in operation. In the Washington memo all impurities were listed on the assumption that not more than five elements would reach the tabulated values. I have, in the meantime, given a much more careful account of what the actual situation is to the committee. I met with them one day in Chicago, came out with them on the train, and have spent two days with them here in Berkeley, and we have had ample opportunity to discuss the purity question and many other aspects of our problem. The information which I have given them now is con-tained in a Chicago report on the feasibility of the 49 project and is as follows: If the concentrations by weight are as given in the accompanying table, then the chance of pre-detonation is 5 per cent, if only one element is present in the listed amount. If n elements are present in the listed amount the chance of pre-detonation is 5n per cent. The chance of a pre-detonation in which the energy release is less than 10,000 tons TNT equivalent is 0.5n per cent. In this range the effects of impurities are additive, and from the actual concen-trations and figures listed one can figure out the probability of any given energy release. In any case, unless the firing mechanism fails completely the energy release will be more than sufficient to destroy the material and to make its recovery impossible. The figures given in the table are in part based on experimental values. In the case of 0 and C the figures represent highly conservative estimates based on the assumption that those isotopes which are dangerous will be as dangerous as the worst element, namely, Be.

Element Concentration by Weight

(Some purity requirements on elements between P and Fe, none beyond Cu)

The only essential changes since the Washington memo are that we have sufficiently examined the experiments somewhat; and that we have studied the case of N carefully enough to be positive that there are no purity requirements on that element. The committee was of the opinion that the purity requirements as they now stand could, with a very high probability, be met. In fact, the Chicago uranium is good enough except for C and 0, and they have made no effort at all to solve this problem. If it were necessary it would be possible to work with depleted C and 0 and so considerably relax the chemical conditions on these elements. In fact, the committee was of the opinion that the major extraction processes which have to be handled automatically and the removal of traces of active material, coupled with the necessity for working in lots of less than 100 grams or of introducing suitable neutron absorbers as "safers," would present greater technical difficulties than the purification. Nevertheless, in our last discussions they seemed convinced that the helium-cooled graphite pile was a good bet.

Now to the second point, the main subject of your letter, where I feel myself on less secure ground. It is, of course, natural that the men we are after will leave a big hole. I may though, in this connection, remind you that when McMillan himself left the Radiation Laboratory for San Diego there were the same dire predictions of disastrous disruption. Nevertheless, the Radiation Laboratory has not only survived but has, as you know, flourished and expanded. In view of this and of the very large number of men of the first rank who are now working on that project, I am inclined not to take too seriously the absolute no's with which we shall be greeted. I believe that it is important to emphasize that we should in any case be willing to let these men have time enough in their old positions to try to minimize the disrup-tion of their leaving. I also agree that a fundamental clarification on this personnel problem, which can hardly be complete without Dr. Bush's participation, will be necessary. The job we have to do will not be possible without personnel substantially greater than that which we now have avail-able, and I should only be misleading you and all others concerned with the S-1 project if I were to promise to get the work done without this help.

The suggestion of Eckhardt as a substitute for Kurie is a welcome one and we shall arrange to talk with him on our next trip east. There are, however, two reasons more substantial than prejudice why the limitation to men who are known to us is sound: 1) that the technical details of this work will in large part have to do with atomic physics so that any man whose experience has been in another field will necessarily be of more limited usefulness; Kurie, for instance, would have had as one of his responsibilities the installation and servicing of the cyclotron. The second reason is that in a tight isolated group such as we are now planning, some warmth and trust in personal relations is an indispensable prerequisite, and we are, of course, able to insure this only in the case of men whom we have known in the past. You will have had from me a note on possible alternatives to Kurie. If none of our suggestions seem practicable we shall see whether Dr. Eckhardt could fill the bill.

With good wishes,

very sincerely yours,
Robert Oppenheimer

J. Robert Oppenheimer's memo for General Leslie R. Groves, April 30, 1943

Los Alamos
April 30, 1943

In accordance with our discussion of last week, I have given some thought to the question of a story about the Los Alamos Project which, if disseminated in the proper way, might serve somewhat to reduce the curiosity of the local population, and at least to delay the dissemination of the truth.

We propose that it be let known that the Los Alamos Project is working on a new type of rocket and that the detail be added that this is a largely electrical device. We feel that the story will have a certain credibility; that the loud noises which we will soon be making here will fit in with the subject; and that the fact, unfortunately not kept completely secret, that we are installing a good deal of electrical equipment, and the further fact that we have a large group of civilian specialists would fit in quite well. We further believe that the remoteness of the site for such a development and the secrecy which has surrounded the project would both be appropriate, and that the circumstance that a good deal of work is in fact being done on rockets, together with the appeal of the word, makes this story one which is both exciting and credible.

This question has been discussed with the governing board of the laboratory who approve it and who further recommend that the technical staff of the laboratory be specially warned neither to contradict nor to support a story of this kind if they should run into it.

J. R. Oppenheimer

Leslie R. Groves to J. Robert Oppenheimer

July 29, 1943

Dear Dr. Oppenheimer:

In view of the nature of the work on which you are engaged, the knowledge of it which is possessed by you and the dependence which rests upon you for its successful accomplishment, it seems necessary to ask you to take certain special precautions with respect to your personal safety.

It is requested that:

(a) You refrain from flying in airplanes of any description; the time saved is not worth the risk. (If emergency demands their use my prior consent should be requested.)

(b) You refrain from driving an automobile for any appreciable distance (above a few miles) and from being without suitable protection on any lonely road, such as the road from Los Alamos to Santa Fe. On such trips you should be accompanied by a competent, able bodied, armed guard. There is no objection to the guard serving as chauffeur.

(c) Your cars be driven with due regard to safety and that in driving about town a guard of some kind should be used, particularly during hours of darkness. The cost of such guard is a proper charge against the United States.

I realize that these precautions may be personally burdensome and that they may appear to you to be unduly restrictive but I am asking you to bear with them until our work is successfully completed.

   Sincerely,
     L. R. Groves
Brigadier General, C. E.

Quebec Agreement
August 19, 1943

Original at: "Articles of Agreement governing collaboration between the authorities of the U.S.A. and U.K. in the matter of Tube Alloys" (Cmd. 9123; London: H. M. Stationery Office, 1954). 

The Citadel, Quebec.

Articles of Agreement Governing Collaboration Between The Authorities of the U.S.A. and the U.K. in the Matter of Tube Alloys

Whereas it is vital to our common safety in the present War to bring the Tube Alloys project to fruition at the earliest moments; and 

Whereas this maybe more speedily achieved if all available British and American brains and resources are pooled; and 

Whereas owing to war conditions it would be an improvident use of war resources to duplicate plants on a large scale on both sides of the Atlantic and therefore a far greater expense has fallen upon the United States;

It is agreed between us

First, that we will never use this agency against each other.

Secondly, that we will not use it against third parties without each other's consent.

Thirdly, that we will not either of us communicate any information about Tube Alloys to third parties except by mutual consent.

The Citadel, Quebec.

Fourthly, that in view of the heavy burden of production falling upon the United States as the result of a wise division of war effort, the British Government recognize that any post-war advantages of an industrial or commercial character shall be dealt with as between the United States and Great Britain on terms to be specified by the President of the United States to the Prime Minister of Great Britain. The Prime Minister expressly disclaims any interest in these industrial and commercial aspects beyond what may be considered by the President of the United States to be fair and just and in harmony with the economic welfare of the world.

And Fifthly, that the following arrangements shall be made to ensure full and effective collaboration between the two countries in bringing the project to fruition:

The Citadel, Quebec.

(a) There shall be set up in Washington a Combined Policy Committee composed of:

 

The functions of this Committee, subject to the control of the respective Governments, will be:

(1) To agree from time to time upon the programme of work to be carried out in the two countries.
(2) To keep all sections of the project under constant review.
(3) To allocate materials, apparatus and plant, in limited supply, in accordance with the requirements of the programme agreed by the Committee.
(4) To settle any questions which may arise on the interpretation or application of this Agreement.

(b) There shall be complete interchange of information and ideas on all sections of the project between members of the Policy Committee and their immediate technical advisers.

The Citadel, Quebec.

(c) In the field of scientific research and development there shall be full and effective interchange of information and ideas between those in the two countries engaged in the same sections of the field.

(d) In the field of design, construction and operation of large-scale plants, interchange of information and ideas shall be regulated by such ad hoc arrangements as may, in each section of the field, appear to be necessary or desirable if the project is to be brought to fruition at the earliest moment. Such ad hoc arrangements shall be subject to the approval of the Policy Committee.

 Aug. 19th 1943

 Approved
Franklin D. Roosevelt
 Winston S. Churchill

J. Robert Oppenheimer to
General Leslie R. Groves

 Los Alamos
November 2, 1943

Dear General Groves:

After you gave me the list during your last visit of the men whom we may expect from the United Kingdom, it occurred to me that it might be wise before they arrive here to give them new names. This refers especially to Niels Bohr. I am thinking of the fact that mail will be addressed to them, that they may on occasion originate or receive long-distance calls, that they will be making some local purchases, and that for all these routine matters it would be preferable if such well known names were not put in circulation.

It has, in fact, troubled us some that we are forced to place calls for Dr. Conant, Fermi, Lawrence, etc. This does not happen very often, but in view of the fact that we try not to use these names over the telephone, the placing of the calls themselves seems to us rather unwise. I doubt whether at this late date it would be practicable to assign new names to those who have been associated with the project in the past. In the case of Bohr and Chadwick I think it would be advisable to do so before they get here.

        Sincerely yours,
J. R. Oppenheimer

Anglo-American Declaration of Trust
June 13, 1944  

This Agreement and Declaration of Trust is made the thirteenth day of June One thousand nine hundred and fourty four by Franklin Delano Roosevelt on behalf of the Government of the United States of America, and by Winston Leonard Spencer Churchill on behalf of the Government of tile United Kingdom of Great Britain and Northern Ireland. The said Governments are hereinafter referred to as "the Two Governments":

Whereas an agreement (hereinafter called the Quebec Agreement) was entered into on the nineteenth day of August One thousand nine hundred and forty three by and between the President of the United States and the Prime Minister of the United Kingdom; and

Whereas it is an object vital to the common interests of those concerned in the successful prosecution of the present war to insure the acquisition at the earliest practicable moment of an adequate supply of uranium and thorium ores; and

Whereas it is the intention of the Two Governments to control to the fullest extent practicable the supplies of uranium and thorium ores within the boundaries of such areas as come under their respective jurisdictions; and

Whereas the Government of the United Kingdom of Great Britain and Northern Ireland intends to approach the Governments of the Dominions and the Governments of India and of Burma for the purpose of securing that such Governments shall bring under control deposits of the uranium and thorium ores within their respective territories; and

Whereas it has been decided to establish a joint organization for the pur-pose of gaining control of the uranium and thorium supplies in certain areas outside the control of the Two Governments and of the Governments of the Dominions and of India and of Burma;

Now it is Hereby Agreed and Declared as Follows:

1. (1) There shall be established in the City of Washington, District of Columbia, a Trust to be known as "The Combined Development Trust".

(2) The Trust shall be composed of and administered by six persons who shall be appointed, and be subject to removal, by the Combined Policy Committee established by the Quebec Agreement.

2. The Trust shall use its best endeavours to gain control of and develop the production of the uranium and thorium supplies situate in certain areas other than the areas under the jurisdiction of the Two Governments and of the governments of the Dominions and of India and of Burma and for that purpose shall take such steps as it may in the com-mon interest think fit to:

a.  Explore and survey sources of uranium and thorium supplies.
b.  Develop the production of uranium and thorium by the acquisition of mines and ore deposits, mining concessions or otherwise.
c.  Provide with equipment any mines or mining works for the production of uranium and thorium
d.  Survey and improve the methods of production of uranium and thorium.
e.  Acquire and undertake the treatment and disposal of uranium and thorium and uranium and thoriurn materials.
f.  Provide storage and other facilities.
g.  Undertake any functions or operations which conduce to the effective carrying out of the purpose of the Trust in the common interest.

3. (1) The Trust shall carry out its functions under the direction and guidance of the Combined Policy Committee, and as its agent, and all ura-nium and thorium ores and supplies and other property acquired by the Trust shall be held by it in trust for the Two Governments jointly, and disposed of or otherwise dealt with in accordance with the direction of the Combined Policy Committee.

(2) The Trust shall submit such reports of its activities as may be required from time to time by the Combined Policy Committee.

4. For the purpose of carrying out its functions, the Trust shall utilize whenever and wherever practicable the established agencies of any of the Two Governments, and may employ and pay such other agents and employees as it considers expedient, and may delegate to any agents or employees all or any of its functions.

5. The Trust may acquire and hold any property in the name of nominees.

6. All funds properly required by the Trust for the performance of its functions shall be provided as to one-half by the Government of the United States of America and the other half by the Government of the United Kingdom of Great Britain and Northern Ireland.

7. In the event of the Combined Policy Committee ceasing to exist, the functions of the Committee under the Trust shall be performed by such other body or person as may be designated by the President for the time being of the United States of America and the Prime Minister for the time being of the United Kingdom of Great Britain and Northern Ireland.

8. The signatories of this Agreement and Declaration of Trust will, as soon as practicable after the conclusion of hostilities, recommend to their respective Governments the extension and revision of this war-time emergency agreement to cover post war conditions and its formalization by treaty or other proper method. This Agreement and Declaration of Trust shall continue in full force and effect until such extension or revision.

(Signed) Franklin D. Roosevelt
On Behalf of the Government of the United States of
America

(Signed) Winston S. Churchill
On Behalf of the Government of the United Kingdom of
Great Britain and Northern Ireland

The Roosevelt-Churchill "Tube Alloys" Deal

September 19, 1944

1. The suggestion that the world should be informed regarding tube alloys, with a view to an international agreement regarding its control and use, is not accepted. The matter should continue to be regarded as of the utmost secrecy; but when a "bomb" is finally available, it might perhaps, after mature consideration, be used against the Japanese, who should be warned that this bombardment will be repeated until they surrender.

2. Full collaboration between the United States and the British Government in developing tube alloys for military and commercial purposes should continue after the defeat of Japan unless and until terminated by joint agreement.

3. Enquiries should be made regarding the activities of Professor Bohr and steps taken to ensure that he is responsible for no leakage of information particularly to the Russians.

J. Robert Oppenheimer to
General Leslie R. Groves

(Los Alamos)
October 6, 1944

Dear General Groves:

I am glad to transmit the enclosed report of Captain Parsons, with the general intent and spirit of which I am in full sympathy. There are a few points on which my evaluation differs somewhat from that expressed in the report and it seems appropriate to mention them at this time.

1. 1 believe that Captain Parsons somewhat misjudges the temper of the responsible members of the laboratory. It is true that there are a few people here whose interests are exclusively "scientific" in the sense that they will abandon any problem that appears to be soluble. I believe that these men are now in appropriate positions in the organization. For the most part the men actually responsible for the prosecution of the work have proven records of carrying developments through the scientific and into the engineering stage. For the most part these men regard their work here not as a scientific adventure, but as a responsible mission which will have failed if it is let drop at the laboratory phase. I therefore do not expect to have to take heroic measures to insure something which I know to be the common desire of the overwhelming majority of our personnel.

2. 1 agree completely with all the comments of Captain Parsons' memorandum on the fallacy of regarding a controlled test as the culmination of the work of this laboratory. The laboratory is operating under a directive to produce weapons; this directive has been and will be rigorously adhered to. The only reason why we contemplate making a test, and why I have in the past advocated this, is because with the present time scales and the present radical assembly design this appears to be a necessary step in the production of a weapon. I do not wish to prejudge the issue: it is possible that information available to us within the next months may make such a test unnecessary. I believe, however, that the probability of this is extremely small.

3. The developmental program of the laboratory, whether or not it has been prosecuted with intelligence and responsibility, is still far behind the minimal requirements set by our directive. This fact, which rests on no perfectionist ideals for long-range development, means that there must in-evitably be some duplication of effort and personnel if the various phases of our program - scientific, engineering and military - are to be carried out without too great mutual interference. It is for this reason that I should like to stress Captain Parsons' remark that a very great strengthening in engineering is required. The organizational experience which the last year has given us is no substitute for competent engineers.

Sincerely yours,
J. R. Oppenheimer

George Harrison's memo for
the Secretary of War (Stimson)
May 1, 1945

War Department
Washington

1 May 1945

Memorandum for the Secretary of War
Subject: Interim Committee on S-1.

Last week you presented to President Truman a fairly complete memorandum on the S-1 project, outlining its genesis, its present state of development and in general its availability for military usage. Your presentation was accompanied by a brief memo which you prepared relative to the broader political and international implications of the problem and the need for post war controls, both national and international. You had in mind the advisability of setting up a committee of particular qualifications for recommending action to the executive and legislative branches of the government when secrecy is no longer fully required. The committee would also be expected to recommend actions to be taken by the War Department in anticipation of the post war problems.

In view of the possibly short time available before actual military use and the relaxation of secrecy, it seems to me - and as you know both Dr. Conant and Dr. Bush agree - that it is becoming more and more important to organize such a committee as promptly as possible. This committee should, I think, be a relatively small committee which should be prepared to serve temporarily or until Congress might appoint a permanent Post War commission to supervise, regulate and control the use of the product.

Certain things, however, must be done now before use if we are to avoid the risk of grave repercussions on the public in general and on Congress in particular. For instance, the committee will need to prepare appropriate announcements to be available for issue (a) by the President and (b) by the War Department as soon as the first bomb is used. These announcements or later publicity would presumably give some of the history of the project, its importance from a military standpoint, its scientific background, and some of its dangers. Most importantly as soon as possible after use some assurance must be given of the steps to be taken to provide the essential controls over post-war use and development, both at home and abroad. With that in mind it will be necessary as soon as possible after use to make recommendations for the necessary congressional legislation covering patents, use, controls, etc.

All of these and many other factors will have to be studied by the committee with the understanding that all recommendations must be for your own approval and for submission to the President for his approval.

It seems clear that some machinery is essential now to provide the way for continuous and effective controls and to insure or provide for the necessary and persistent research and development of the possibilities of atomic energy in which the United States now leads the way. If properly controlled by the peace loving nations of the world this energy should insure tile peace of the world for generations. If misused it may lead to the complete destruc-tion of civilization.

In the circumstances I suggest that a committee of six or seven be set up at once to study and report on the whole problem of temporary war controls and publicity, and to survey and make recommendation on post-war research, development and controls, and the legislation necessary to effec-tuate them.

The members of this committee should be appointed by you as Secretary of War subject to the approval of the President. When appointed the committee will need promptly to organize appropriate panels to aid in its work-panels of specially qualified scientists, Army and Navy personnel, Congressional advisers, legislative draftsmen and others.

George L. Harrison

Source: Manhattan Engineer District -- Top Secret, Harrison-Bundy files, folder 69, National Archives, Washington, D.C.

Glenn T. Seaborg to Ernest O. Lawrence,
June 13, 1945

June 13, 1945

Mr. Ernest O. Lawrence
Radiation Laboratory
University of California
Berkeley, California

Dear Ernest:

I am writing to give you my opinions and suggestions on the question of the course to be taken for nuclear weapons in the immediate future, and also on the question of the post war future for neucleonics. My purpose is to express myself briefly here upon such political and social questions as the release of information, use of the weapon in the present war and post war control of the weapon, rather than upon the actual research program which would be difficult to cover in a short communication. As you know, it is difficult to express unqualified opinions on such political and social questions as these on the basis of information available to us, and therefore I have the feeling that my views could change if there is important information, espe-cially in respect to the present war, which is not at our disposal. I do want to say, however, that these present opinions are shared almost unanimously by the people associated with me in my section of the Chemistry Division here. For the purpose of brevity I shall list our conclusions with little or no discussion of the basis for the development of these conclusions. These opinions of course are based on the assumption that the development of a nuclear weapon of great destructive capacity is now essentially an accomplished fact.

I believe that the basic facts concerning the successful release of nuclear energy and its immense destructive possibilities should be made public and impressed upon public opinion in this country and all over the world very soon. There should be essentially two stages in the release of this information, disclosure to the general public of the results which have been obtained, and the publication of these results through more or less regular scientific channels. The first of these, disclosure to the public, should come soon and probably need go no further than to describe the destructive possibilities of the self-sustaining chain reaction with the heavy isotopes, with some non-technical description of the achievements in the manufacturing of such fissionable material. The method to be employed for this release should be chosen only after much careful study; perhaps a stepwise release, studying the effect at each step, should be used. The publication in regular scientific channels, which is not an urgent matter, should come later but should then go at least so far as to cover the entire scientific basis of the accomplishments. This would include such items as the existence of and the important nuclear properties of the heavy isotopes, the fundamental information about the nuclear chain reactions, the basic information concerned with the methods for the separation of the uranium isotopes, the fundamental information about chain-reacting structures used in the manufacture of the heavy synthetic isotopes, and the fundamental chemical properties of the new synthetic elements. Perhaps it would be all right to withhold indefinitely some of the information with respect to the actual detailed designs of the major manufacturing installations. This might not be construed as too unnatural a procedure in that the maintenance of secrecy in regard to ordnance infor-mation and in respect to many industrial operations has an established pre-cedent in this country.
     
With respect to use in the present war we suggest the following. Our country would probably lose some of the confidence of our Allies and dete-riorate our moral position with respect to the outlawing of future use of the weapon if we were to use it directly upon Japan without warning. It seems certain that the moral position of our country would be greatly strengthened if the first demonstration of this weapon were made upon some uninhabited island in the presence of the invited representatives of all the leading countries of the world, including Japan. Following such a successful demonstration Japan would be given an ultimatum to surrender and if this ultimatum was not accepted, the question of then using the weapon would be decided by the United States together with the United Nations; the sanction of other leading nations of the world would be important. The question of international control of this weapon, touched upon in the next paragraph, should of course be vigorously pursued immediately after the demonstration.
     
The question of the post war control of nucleonics is a most difficult one. The above-described disposition of the weapon in the present war amounts essentially to subordinating its use now toward the broader goal of insuring control over it in the longer post war future. One method of post war control lies in the complete outlawing of nucleonics research throughout the world; I believe that this method, which amounts to advocating the suppression of science, is too unnatural for it to succeed. We would favor, rather, if it could possibly be made consistent with our national security and with world secu-rity, free research in nucleonics throughout the world with complete ex-change of all the basic information and some degree of control through an international organization. Probably the best method of control lies in the control of the raw materials, although this is admittedly difficult. Completely free research in nucleonics, unfortunately, makes it possible for any country to accumulate a stockpile of fissionable material. It is the opinion of some that probably the only method of maintaining control under such conditions would involve world-wide pooling to form a stockpile of fissionable material to be used by the international organization for policing purposes; I do not feel qualified to express an opinion on this complicated possibility. As suggested by Szilard, perhaps control could be effected, at least in the case of some of the fissionable material, by denaturization, i.e. by mixing it with suitable isotopes to spoil its use for explosive purposes without interfering too much with its use for research purposes such as power pile developments.
     
With respect to the organization of post war research in nucleonics in our country, I believe that the establishment, with government aid, of about four large research laboratories at four of the major universities is a good idea. These laboratories should form a sort of a foundation for the country's re-search program and should include men who are able and willing to advise outlying laboratories as to research program. The outlying laboratories might consist of Government laboratories working on the more practical aspects of the field, and also regular university and industrial laboratories supported by Government contracts or grants-in-aid. This government-aided research would be concerned with the application of nucleonics to military and defense purposes and with such other applications as are recognized as governmental purposes. There should be no reason to restrict the development of nucleonics along other lines and industry should be free to work on its ap-plication to such fields as power piles, the manufacture of radioactive iso-topes and other fields which they may wish to develop.

Sincerely yours,
        G. T. Seaborg
 

Source:  Seaborg papers, Lawrence Berkeley Laboratory.

Recommendations on the Immediate
Use of Nuclear Weapons
(by the Scientific Panel of the Interim Committee, June 16, 1945)

You have asked us to comment on the initial use of the new weapon. This use, in our opinion, should be such as to promote a satisfactory adjustment of our international relations. At the same time, we recognize our obligation to our nation to use the weapons to help save American lives in the Japanese war.

(1) To accomplish these ends we recommend that before the weapons are used not only Britain, but also Russia, France, and China be advised that we have made considerable progress in our work on atomic weapons, and that we would welcome suggestions as to how we can cooperate in making this development contribute to improved international relations.

(2) The opinions of our scientific colleagues on the initial use of these weapons are not unanimous: they range from the proposal of a purely technical demonstration to that of the military application best designed to induce surrender. Those who advocate a purely technical demonstration would wish to outlaw the use of atomic weapons, and have feared that if we use the weapons now our position in future negotiations will be prejudiced. Others emphasize the opportunity of saving American lives by immediate military use, and believe that such use will improve the international prospects, in that they are more concerned with the prevention of war than with the elimination of this specific weapon. We find ourselves closer to these latter views; we can propose no technical demonstration likely to bring an end to the war; we see no acceptable alternative to direct military use.

(3) With regard to these general aspects of the use of atomic energy, it is clear that we, as scientific men, have no proprietary rights. It is true that we are among the few citizens h have had occasion to give thoughtful consideration to these problems during the past few years. We have, however, no claim to special competence in solving the political, social, and military problems which are presented by the advent of atomic power.

Source: Michael B. Stoff et al., eds., The Manhattan Project: A Documentary Introduction to the Atomic Age (Philadelphia: Temple University Press, 1991), 150.

George Harrison's memo for the Secretary of War (Stimson), June 26, 1945

WAR DEPARTMENT
WASHINGTON

26 June 1945
TOP SECRET

Memorandum for the Secretary of War:

Many of the scientists who have been working on S-1 have expressed considerable concern about the future dangers of the development of atomic power. Some are fearful that no safe system of international control can be established. They, therefore, envisage the possibility of an armament race that may threaten civilization.

One group of scientists, working in the Chicago Laboratories, urges that we should not make use of the bomb, so nearly completed, against any enemy country at this time. They feel that to do so might sacrifice our whole moral position and thus make it more difficult for us to be the leaders in proposing or enforcing any system of international control designed to make this tremendous force an influence towards the maintenance of world peace rather than an uncontrollable weapon of war.

This anonymous statement of the Chicago scientists was submitted for comment to the Panel of Scientists appointed by the Interim Committee. Their answer was that they saw no acceptable alternative to direct military use since they believe that such use would be an obvious means of saving American lives and shortening the war.

It is interesting that practically all of the scientists, including those on the panel, feel great concern for the future if atomic power is not controlled through some effective international mechanism. Accordingly, most of them believe that one of the effective steps in establishing such a control is the assurance that, after this war is over, there shall be a free interchange of scientific opinion throughout the world supplemented, if possible, by some system of inspection. This they admit is a problem of the future. In the meantime, however, they feel that we must, even before actual use, briefly advise the Russians of our progress.

This matter of notice to the Russians was made a subject of thorough discussion at the last meeting of the Interim Committee on June 21. It was unanimously agreed that in view of the importance of securing an effective future control, and in view of the fact that most of the story, other than production secrets, will become known in-[sic] in any event, there would be considerable advantage, if a suitable opportunity arises at the "Big Three" meeting, in having the President advise the Russians simply that we are working intensely on this weapon and that, if we succeed as we think we will, we plan to use it against the enemy. Such a statement might well be supplemented by the statement that in the future, after the war, we would expect to discuss the matter further with a view to insuring that this means of warfare will become a substantial aid in preserving the peace of the world rather than a weapon of terror and destruction.

It was felt by the Committee that if the Russians should ask for more details now rather than later or if they should raise questions as to time-tables, methods of production, etc., they should be told that we are not yet ready to discuss the subject beyond the simple statement suggested above. Our purpose is merely to let them know that we did not wish to proceed with actual use without giving them prior information that we intend to do so. Not to give them this prior information at the time of the "Big Three" Conference and within a few weeks thereafter to use the weapon and to make fairly complete statements to the world about its history and development, might well make it impossible ever to enlist Russian cooperation in the set-up of future international controls over this new power.

It was agreed by the Committee that in view of the provisions of the Quebec Agreement it would be desirable to discuss this whole aspect of the question with the Prime Minister in advance of the "Big Three" Con-ference.

[signed] George L. Harrison

Source: Manhattan Engineer District -- Top Secret, Harrison-Bundy files, folder 77, National Archives, Washington, D.C.

The Trinity Test
July 16, 1945

Alamogordo, New Mexico
On a quiet stretch of desert a mushroom cloud rises into the air, emitting an eerie blue glow due to high levels of radiation.

Several scientists who work at the Los Alamos National Laboratory witness the explosion of the first atomic bomb. Their eyewitness accounts were stamped secret.

Luis W. Alvarez
Enrico Fermi
0. R. Frisch
Kenneth Greisen
Edwin M. McMillan
Philip Morrison
Robert Serber
Maurice M. Shapiro
Cyril S. Smith
Victor Weisskopf

General Groves' Report on the Trinity Test

Washington, 18 July 1945. 

Top secret 

MEMORANDUM FOR THE SECETARY OF WAR

SUBJECT: The Test.

1. This is not a concise, formal military report but an attempt to recite what I would have told you if you had been here on my return from New Mexico.

2. At 0530, 16 July 1945, in a remote section of the Alamogordo Air Base, New Mexico, the first full scale test was made of the implosion type atomic fission bomb. For the first time in history there was a nuclear explosion.

And what an explosion! 

The bomb was dropped from an airplane but was exploded on a platform on top of a 100-foot high steel tower.

3. The test was successful beyond the most optimistic expectations of anyone. Based on the data which it has been possible to work up to date, I estimate the energy generated to be in excess of the equivalent of 15,000 to 20,000 tons of TNT; and this is a conservative estimate. Data based on measurements which we have not yet been able to reconcile would make the energy release several times the conservative figure. There were tremendous blast effects. For a brief period there was a lighting effect within a radius of 20 miles equal to several suns in midday; a huge ball of fire was formed which lasted for several seconds. This ball mushroomed and rose to a height of over ten thousand feet before it dimmed. The light from the explosion was seen clearly at Albuquerque, Santa Fe, Silver City, El Paso and other points generally to about 180 miles away. The sound was heard to the same distance in a few instances but generally to about 100 miles. Only a few windows were broken although one was some 125 miles away. A massive cloud was formed which surged and billowed upward with tremendous power, reaching the substratosphere at an elevation of 41,000 feet, 36,000 feet above the ground, in about five minutes, breaking without interruption through a temperature inversion at 17,000 feet which most of the scientists thought would stop it. Two supplementary explosions occurred in the cloud shortly after the main explosion. The cloud contained several thousand tons of dust picked up from the ground and a considerable amount of iron in the gaseous form. Our present thought is that this iron ignited when it mixed with the oxygen in the air to cause these supplementary explosions. Huge concentrations of highly radioactive materials resulted from the fission and were contained in this cloud.

4. A crater from which all vegetation had vanished, with a diameter of 1200 feet and a slight slope toward the center, was formed. In the center was a shallow bowl 130 feet in diameter and 6 feet in depth. The material within the crater was deeply pulverized dirt. The material within the outer circle is greenish and can be distinctly seen from as much as 5 miles away. The steel from the tower was evaporated. 1500 feet away there was a four-inch iron pipe 16 feet high set in concrete and strongly guyed. It disappeared completely.
 
 5. One-half mile from the explosion there was a massive steel test cylinder weighing 220 tons. The base of the cylinder was solidly encased in concrete. Surrounding the cylinder was a strong steel tower 70 feet high, firmly anchored to concrete foundations. This tower is comparable to a steel building bay that would be found in typical 15 or 20 story skyscraper or in warehouse construction. Forty tons of steel were used to fabricate the tower which was 70 feet high, the height of a six story building. The cross bracing was much stronger than that normally used in ordinary steel construction. The absence of the solid walls of a building gave the blast a much less effective surface to push against. The blast tore the tower from its foundation, twisted it, ripped it apart and left it flat on the ground. The effects on the tower indicate that, at that distance, unshielded permanent steel and masonry buildings would have been destroyed. I no longer consider the Pentagon a sage shelter from such a bomb. Enclosed are a sketch showing the tower before the explosion and a telephotograph showing what it looked like afterwards. None of us had expected it to be damaged.

6.The cloud traveled to a great height first in the form of a ball, then mushroomed, then changed into a long trailing chimney-shaped column and finally was sent in several directions by the variable winds at the different elevations. It deposited its dust and radioactive materials over a wide area. It was followed and monitored by medical doctors and scientists with instruments to check its radioactive effects. While here and there the activity on the ground was fairly high, at no place did it reach a concentration which required evacuation of the population. Radioactive material in small quantities was located as much as 120 miles away. The measurements are being continued in order to have adequate data with which to protect the Government's interests in case of future claims. For a few hours I was none too comfortable about the situation.

7. For distances as much as 200 miles away, observers were stationed to check on blast effects, property damage, radioactivity and reactions of the population. While complete reports have not yet been received, I now know that no persons were injured nor was there any real property damage outside our Government area. As soon as all the voluminous data can be checked and correlated, full technical studies will be possible. 

8. Our long range weather predictions had indicated that we could expect weather favorable for our test beginning on the morning of the 17th and continuing for four days. This was almost a certainty if we were to believe our long range forecasters. The prediction for the morning of the 16th was not so certain but there was about an 80% chance of the conditions being suitable. During the night there were thunder storms with lightning flashes all over the area. The test had been originally set for 0400 hours and all the night through, because of the bad weather, there were urgings from many of the scientists to postpone the test. Such a delay might well have crippling results due to mechanical difficulties in our complicated test set-up. Fortunately, we disregarded the urgings. We held firm and waited the night through hoping for suitable weather. We had to delay an hour and a half, to 0530, before we could fire. This was 30 minutes before sunrise.

9. Because of bad weather, our two B-29 observation airplanes were unable to take off as scheduled from Kirtland Field at Albuquerque and when they finally did get off, they found it impossible to get over the target because of the heavy clouds and the thunder storms. Certain desired observations could not be made and while the people in the airplanes saw the explosion from a distance, they were not as close as they will be in action. We still have no reason to anticipate the loss of our plans in an actual operation although we cannot guarantee safety.

10. Just before 1100 the news stories from all over the state started to flow into the Albuquerque Associated Press. I then directed the issuance by the Commanding Officer, Alamogordo Air Base of a news release as shown on the inclosure. With the assistance of the Office of Censorship we were able to limit the news stories to the approved release supplemented in the local papers by brief stories from the many eyewitnesses not connected with our project. One of these was a blind woman who saw the light.

11. Brigadier General Thomas F. Farrell was at the control shelter located 10,000 yards south of the point of explosion. His impressions are given below:

"The scene inside the shelter was dramatic beyond words. In and around the shelter were some twenty-odd people concerned with last minute arrangements prior to firing the shot. Included were: Dr. Oppenheimer, the Director who had borne the great scientific burden of developing the weapon from the raw materials made in Tennessee and Washington and a dozen of his key assistants -- Dr. Kistiskowsky, who developed the highly special explosive; Dr. Bainbridge, who supervised all the detailed arrangements for the test; Dr. Hubbard, the weather expert, and several others. Besides these, there were a handful of soldiers, two or three Army officers and one Naval officer. The shelter was cluttered with a great variety of instruments and radios.

"For some hectric two hours preceding the blast, General Groves stayed with the Director, walking with him and steadying his tense excitement. Every time the director would be about to explode because of some untoward happening, General Groves would take him off and walk with him in the rain, counselling with him and reassuring him that everything would be all right. At twenty minutes before zero hour, General Groves left for his station at the base camp, first because it provided a better observation point and second, because of our rule that he and I must not be together in situations where there is an element of danger, which existed at both points.

"Just after General Groves left, announcements began to be broadcast of the interval remaining before the blast. They were sent by radio to the other groups participating in and observing the test. As the time interval grew smaller and changed from minutes to seconds, the tension increased by leaps and bounds. Everyone in that room knew the awful potentialities of the thing that they thought was about to happen. The scientists felt that their figuring must be right and that the bomb had to go off but there was in everyone's mind a strong measure of doubt. The feeling of many could be expressed by "Lord, I believe; help Thou mine unbelief." We were reaching into the unknown and we did not know what might come of it. It can be safely said that most of those present--Christian, Jew and Athiest--were praying and praying harder than they had ever prayed before. If the shot were successful, it was a justification of the several years of intensive effort of tens of thousands of people--statesmen, scientists, engineers, manufacturers, soldiers, and many others in every walk of life.

"In that brief instant in the remote New Mexico desert the tremendous effort of the brains and brawn of all these people came suddenly and startingly to the fullest fruition. Dr. Oppenheimer, on whom had rested a very heavy burden, grew tenser as the last seconds ticked off. He scarcely breathed. He held on to a post to steady himself. For the last few seconds, he started directly ahead and then when the announcer shouted "Now!" and there came this tremendous burst of light followed shortly thereafter by the deep growing roar of the explosion, his face relaxed into an expression of tremendous relief. Several of the observers standing back of the shelter to watch the lighting effects were knocked flat by the blast.

"The tension in the room let up and all started congratulating each other. Everyone sensed "This is it!" No matter what might happen now all knew that the impossible scientific job had been done. Atomic fission would no longer be hidden in the cloisters of the theoretical physicists' dreams. It was almost full grown at birth. It was a great new force to be used for good or for evil. There was a feeling in that shelter that those concerned with its nativity should dedicate their lives to the mission that it would always be used for good and never for evil.

"Dr. Kistiakowsky, the impulsive Russian, threw his arms around Dr. Oppenheimer and embraced him with shouts of glee. Others were equally enthusiastic. All the pent-up emotions were released in those few minutes and all seemed to sense immediately that the explosion had far exceeded the most optimistic expectations and wildest hopes of the scientists. All seemed to feel that they had been present at the birth of a new age--The Age of Atomic Energy--and felt their profound responsibility to help in guiding into right channels the tremendous forces which had been unlocked for the first time in history.

"As to the present war, there was a feeling that no matter what else might happen, we now had the means to insure its speedy conclusion and save thousands of American lives. As to the future, there had been brought into being something big and something new that would prove to be immeasurably more important than the discovery of electricity or any of the other great discoveries which have so affected our existence.

"The effects could well be called unprecedented, magnificent, beautiful, stupendous and terrifying. No man-made phenomenon of such tremendous power had ever occurred before. The lighting effects beggared description. The whole country was lighted by a searing light with the intensity many times that of the midday sun. It was golden, purple, violet, gray and blue. It lighted every peak, crevasse and ridge of the nearby mountain range with a clarity and beauty that cannot be described but must be seen to be imagined. It was that beauty the great poets dream about but describe most poorly and inadequately. Thirty seconds after the explosion came first, the air blast pressing hard against the people and things, to be followed almost immediately by the strong, sustained, awesome roar which warned of doomsday and made us feel that we puny things were blasphemous to dare tamper with the forces heretofore reserved to The Almighty. Words are inadequate tools for the job of acquainting those not present with the physical, mental and psychological effects. It had to be witnessed to be realized."

12. My impressions of the night's high points follow:

After about an hour's sleep I got up at 0100 and from that time on until about five I was with Dr. Oppenheimer constantly. Naturally he was nervous, although his mind was working at its usual extraordinary efficiency. I devoted my entire attention to shielding him from the excited and generally faulty advice of his assistants who were more than disturbed by their excitement and the uncertain weather conditions. By 0330 we decided that we could probably fire at 0530. By 0400 the rain had stopped but the sky was heavily overcast. Our decision became firmer as time went on. During most of these hours the two of us journeyed from the control house out into the darkness to look at the stars and to assure each other that the one or two visible stars were becoming brighter. At 0510 I left Dr. Oppenheimer and returned to the main observation point which was 17,000 yards from the point of explosion. In accordance with our orders I found all personnel not otherwise occupied massed on a bit of high ground.

At about two minutes of the scheduled firing time all persons lay face down with their feet pointing towards the explosion. As the remaining time was called from the loud speaker from the 10,000 yard control station there was complete silence. Dr. Conant said he had never imagined seconds could be so long. Most of the individuals in accordance with orders shielded their eyes in one way or another. There was then this burst of light of a brilliance beyond any comparison. We all rolled over and looked through dark glasses at the ball of fire. About forty seconds later came the shock wave followed by the sound, neither of which seemed startling after our complete astonishment at the extraordinary lighting intensity. Dr. Conant reached over and we shook hands in mutual congratulations. Dr. Bush, who was on the other side of me, did likewise. The feeling of the entire assembly was similar to that described by General Farrell, with even the uninitiated feeling profound awe. Drs. Conant and Bush and myself were struck by an even stronger feelinlg that the faith of those who had been responsible for the initiation and the carrying on of this Herculean project had been justified. I personally thought of Blondin crossing Niagara Falls on his tight rope, only to me this tight rope had lasted for almost three years and of my repeated confident-appearing assurances that such a thing was possible and that we would do it.

13. A large group of observers were stationed at a point about 27 miles north of the point of explosion. Attached is a memorandum written shortly after the explosion by Dr. E.O. Lawrence which may be of interest.

14. While General Farrell was waiting about midnight for a commercial airplane to Washington at Albuquerque--120 miles away from the site--he overheard several airport employees discussing their reaction to the blast. One said that he was out on the parking apron; it was quite dark; then the whole southern sky was lighted as though by a bright sun; the light lasted several seconds. Another remarked that if a few exploding bombs could have such an effect, it must be terrible to have them drop on a city.

15. My liaison officer at the Alamogordo Air Base, 60 miles away, made the following report:

"There was a blinding flash of light that lighted the entire northwestern sky. In the center of the flash, there appeared to be a huge billow of smoke. The original flash lasted approximately 10 to 15 seconds. As the first flash died down, there arose in the approximate center of where the original flash had occurred an enormous ball of what appeared to be fire and closely resembled a rising sun that was three-fourths above a mountain. The ball of fire lasted approximately 15 seconds, then died down and the sky resumed an almost normal appearance.

"Almost immediately, a third, but much smaller, flash and billow of smoke of a whiteish-orange color appeared in the sky, again lighting the sky for approximately 4 seconds. At the time of the original flash, the field was lighted well enough so that a newspaper could easily have been read. The second and third flashes were of much lesser intensity.

"We were in a glass-enclosed control tower some 70 feet above the ground and felt no concussion or air compression. There was no noticeable earth tremor although reports overheard at the Field during the following 24 hours indicated that some believed that they had both heard the explosion and felt some earth tremor."

16. I have not written a separate report for General Marshall as I feel you will want to show this to him. I have informed the necessary people here of our results. Lord Halifax after discussion with Mr. Harrison and myself stated that he was not sending a full report to his government at this time. I informed him that I was sending this to you and that you might wish to show it to the proper British representatives.

17. We are all fully conscious that our real goal is still before us. The battle test is what counts in the war with Japan.

18. May I express my deep personal appreciation for your congratulatory cable to us and for the support and confidence which I have received from you ever since I have had this work under my charge.

19. I know that Colonel Wyle will guard these papers with his customary extraordinary care.

L.R.GROVES,
Major General, USA 

Source: Foreign Relations of the United States: Conference of Berlin (Potsdam) , vol. 2, 1361-1368.

Memo for General Arnold
July 24, 1945

MEMORANDUM FOR GENERAL ARNOLD

SUBJECT: Groves Project

1. The following plan and schedule for initial attacks using special bombs have been worked out:

a. The first bomb (gun type) will be ready to drop between August 1 and 10 and plans are to drop it the first day of good weather following readiness.

b. The following targets have been selected: Hiroshima, Kokura, Niigata and Nagasaki.

(1) Hiroshima (population 350,000) is an "Army" city; a major POE; has large QM and supply depots; has considerable industry and several small shipyards.

(2) Nagasaki (population 210,000) is a major shipping and industrial center of Kyushu.

(3) Kokura (population 178,000) has one of the largest army arsenals and ordnance works; has the largest railroad shops on Kyushu: and has large munitions storage to the south.

(4) Niigata (population 150,000) is an important industrial city, building machine tools, diesel engines, etc., and is a key port for shipping to the mainland.

c. All four cities are believed to contain large numbers of key Japanese industrialists and political figures who have sought refuge from major destroyed cities.

d. The attack is planned to be visual to insure accuracy and will await favorable weather. The four targets give a very high probability of one being open even if the Weather varies from that forecast, as they are considerably separated.

e. The bomb will be carried in a master airplane accompanied by two other project B-29's with observers and special instruments.

f. The three B-29's will take off from North Field Tinian, and fly via Iwo Jima. The use of fighter escort will be determined by General Spaatz upon consideration of all operational factors.

g. The master plane will attack the selected target from [?] feet plus altitudewill immediately upon release of the bomb make a steep diving turn away from the target to achieve maximum slant range distance as quickly as possible. Recording planes and fighters if employed will be kept several miles from the target. The particiating planes are believed to be safe from the effects of the bomb.

h. The bomb will be detonated by radar proximiter fuze about 2,000 feet above the ground.

i. Emergency arrangements have been provided at Iwo Jima for handling the bomb if required.

2. Two tested type bombs are expected to be available in August, one about the 6th and another the 24th. General Groves expects to have more information on future availabilities in a few days which will be furnished you when received.

3. The above has been discussed with Generals Spaatz and Eaker who concur.

JOHN N. STONE
Colonel, GSC

 

Leslie R. Groves' Memo to the
Chief of Staff (George C. Marshall)

30 July 1945

MEMORANDUM TO THE CHIEF OF STAFF

1. The following additional conclusions have been drawn from the test in New Mexico with respect to the probable effects of the combat bomb which will be exploded about 1800 feet in the air:

a. Measured from the point on the ground directly below the explo-sion the blast should be lethal to at least 1000 feet. Between 2500 and 3500 feet, blast effects should be extremely serious to personnel. Heat and flame should be fatal to about 1500 to 2000 feet.

b. At 10 miles for a few thousandths of a second the light will be as bright as a thousand suns; at the end of a second, as bright as one or possibly two suns. The effect on anyone about a half mile away who looks directly at the explosion would probably be permanent sight impairment; at one mile, tem-porary blindness; and up to and even beyond ten miles, temporary sight impairment. To persons who are completly unshielded, gamma rays may be lethal to 3500 feet and neutrons to about 2000 feet.

c. No damaging effects are anticipated on the ground from radioactive materials. These effects at New Mexico resulted from the low altitude from which the bomb was set off.

d. Practically all structures in an area of one or two square miles should be completely demolished and a total area of six to seven square miles should be so devastated that the bulk of the buildings would have to have major repairs to make them habitable.

e. At New Mexico tanks could have gone through the immediate explo-sion area at normal speeds within thirty minutes after the blast. With the explosion at the expected 1800 feet, we think we could move troops through the area immediately preferably by motor but on foot if desired. The units should be preceded by scouts with simple instruments. The nearest exposed personnel should not be nearer to the blast than six miles plus the necessary allowance for bombing inaccuracy and they would require a high order of discipline and special but simple instructions. As an extra precaution, extra special dark glasses might be issued to all commanders of units as large as a platoon. If dropped on the enemy lines, the expected effect on the enemy would be to wipe out his resistance over an area 2000 feet in diameter; to paralyze it over an area a mile in diameter; and to impede it seriously over an area five miles in diameter. Troops which were in deep cave shelters at distances of over a mile should not be seriously affected. Men in slit trenches within 800 feet should be killed by the blast.

2. The energy of the test explosion has been broken down as follows:
Total theoretical energy contained in the bomb at 100% efficiency was [sensitive information deleted]. Of this amount, 21,000 to 24,000 tons were converted into actual energy made up of.
Blast - 10,500 tons minimum, 13,500 maximum
Light - 2500 tons
Waste Heat - 8000 tons, about 4000 of which went into the air and 4000 into the ground. If the explosion had been at the combat al-titude of 1800 feet, most of the 4000 that went into the ground would have been converted into blast, making the total blast from 14,000 to 17,000 tons.

3. There is a definite possibility, [sensitive information deleted] as we increase our rate of production at the Hanford Engineer Works, with the type of weapon tested that the blast will be smaller due to detonation in 19advance of the optimum time. But in any event, the explosion should be on the order of thousands of tons. The difficulty arises from an undesirable isotope which is created in greater quantity as the production rate increases.

4. The final components of the first gun type bomb have arrived at Tinian, those of the first implosion type should leave San Francisco by air-plane early on 30 July. I see no reason to change our previous readiness predictions on the first three bombs. In September, we should have three or four bombs. One of these will be made from 235 material and will have a smaller effectiveness, about two-thirds that of the test type, but by November, we should be able to bring this up to full power. There should be either four or three bombs in October, one of the lesser size. In November there should be at least five bombs and the rate will rise to seven in December and increase decidedly in early 1946. By some time in November, we should have the effectiveness of the 235 implosion type bomb equal to that of the tested plutonium implosion type.

5. By mid-October we could increase the number of bombs slightly by changing our design now to one using both materials in the same bomb. I have not made this change because of the ever present possibilities of difficulties in new designs. We could, if it were wise, change our plans and develop the combination bomb. But if this is to be done, it would entail an initial ten-day production setback which would be caught up in about a month's time; unless the decision to change were made before I August, in which case it would probably not entail any delay. From what I know of the world situation, it would seem wiser not to make this change until the effects of the present bomb are determined.

L. R. GROVES
Major General, U.S.A.

Source:  Manhattan Engineer District -- Top Secret, Manhattan Project File, Folder 4, Trinity Test, National Archives,

Truman Tells Stalin About the Bomb

Truman-Stalin Conversation, Tuesday, July 24, 1945, 7:30 P.M.

Present:

United States: President Truman
Soviet Union: Generalissimo Stalin Mr. Pavlov

Truman gives the following account of the conversation in Year of Decisions , page 416: "On July 24 I casually mentioned to Stalin that we had a new weapon of unusual destructive force. The Russian Premier showed no special interest. All he said was that he was glad to hear it and hoped we would make 'good use of it against the Japanese.'"

Byrnes gives the following information on the conversation in Speaking Frankly , page 263: "At the close of the meeting of the Big Three on the afternoon of July 24, the President walked around the large circular table to talk to Stalin. After a brief conversation the President rejoined me and we rode back to the 'Little White House' together. He said he had told Stalin that, after long experimentation, we had developed a new bomb far more destructive than any other known bomb, and that we planned to use it very soon unless Japan surrendered. Stalin's only reply was to say that he was glad to hear of the bomb and he hoped we would use it."

Leahy's account is as follows ( I Was There , page 429): "At the plenary session on July 24, Truman walked around to Stalin and told him quietly that we had developed a powerful weapon, more potent than anything yet seen in war. The President said later that Stalin's reply indicated no especial interest and that the Genaralissimo did not seem to have any conception of what Truman was talking about. It was simply another weapon and he hoped we would use it effectively."

Churchill, who was also an eye-witness to the conversation, gives the following information ( Triumph and Tragedy , pages 669-670): "Next day, July 24, after our plenary meeting had ended and we all got up from the round table and stood about in twos and threes before dispersing, I saw the President go up to Stalin, and the two conversed alone with only their interpreters. I was perhaps five yards away, and I watched with the closest attention the momentous talk. I know what the President was going to do. What was vital to measure was its effect on Stalin. I can see it all as if it were yesterday. He seemed to be delighted.... As we were waiting for our cars I found myself near Truman. 'How did it go?' I asked. 'He never asked a question,' he replied."

Source: Foreign Relations of the United States: Conference of Berlin (Potsdam), vol. 1, 378.

Petition to the President of the United States by Scientists at the Chicago Metallurgical Laboratory

July 17, 1945 

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 the 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 the light of the considerations presented in this petition as well as all the other moral responsibilities which are involved.  [Signed by 69 scientists at the Chicago Metallurgical Laboratory] 

Source: Dennis Merrill, ed., Documentary history of the Truman Presidency , vol. 1: The decision to drop the atomic bomb on Japan (University Publications of America:1995), 219.