The Atomic Bomb: “The Year of Decisions”


Document A: Excerpts from Truman’s diary from the Potsdam conference (Dated entries from July 17 to August 10, 1945)
Found online:

July 17, 1945 Truman Diary

Just spent a couple of hours with Stalin. Joe Denis called on Maiski and made the date last night for noon today. Promptly a few minutes before twelve I looked up from the desk and there stood Stalin in the doorway. I got to my feet and advanced to meet him. He put out his hand and smiled. I did the same, we shook, I greeted Molotov and the interpreter and we sat down. After the usual polite remarks we got down to business. I told Stalin that I am no diplomat but usually said yes or no to questions after hearing all the argument. It pleased him. I asked him if he had the agenda for the meeting. He said he had some more questions to present. I told him to fire away. He did and it is dynamite--but I have some dynamite too which I'm not exploding now.

He wants to fire Fianco, to which I wouldn't object and divide up the Italian colonies and other mandates, some no doubt that the British have Then he got on the Chinese situation told us what agreements had been reached and what was in abeyance. Most of the big points are settled. He'll be in the Jap War on August 15th. Fini Japs when that comes about. We had lunch, talked socially, put on a real sham drinking toasts to everyone, then had pictures made in the back yard. I can deal with Stalin. He is honest--but smart as hell.  

July 19, 1945 Truman Diary

Stalin was a day late in arriving. It was reported that he was not feeling up to par. He called on me as soon as he arrived. It was about 11 A.M. He, Molotov, Vishinski and Pavlov stayed for lunch. We had a most pleasant conference and Stalin assured me that Russia intended to carry out the Yalta agreements and to enter the war against Japan in August.  

July 20, 1945 Truman Diary

Jim Blair now Lt. Col. came in for breakfast. Harry left for Paris & N.Y. Sure hated to see him go. Discussed German situation with Jim. He had been in command of clean up detail which prepared the area for American occupation especially for our conference delegation. Said it was the filthiest place imaginable. No sanitary arrangement whatever. Toilets all full and all stopped up. Basements used as outdoor toilets. Said the sewer system evidently hadn't worked for months. Same all over town. Said Germans are sore and sullen. That we would not treat them rough enough. Russians treated 'em too rough and too kindly. Anyway its a hell of a mess any way it's taken.

Saw Gen. Omar Bradley about taking over the Vets. bureau. Will take over Aug. 15th. Talked to Gen. Eisenhower about government of Germany along same lines as I'd talked to Gen. Clay. Got a concrete program to present.

Raised a flag over our area in Berlin. It is the flag raised in Rome, North Africa and Paris. Flag was on the White House when Pearl Harbor happened. Well be raised over Tokyo.

Uncle Joe looked drawn and tired today and the P.M. seemed lost. I told 'em U.S. had ceased to give away it's assets without returns.

July 25, 1945 Truman Diary

We met at 11 A.M. today. That is Stalin, Churchill and the U.S. President. But I had a most important session with Lord Mountbattan & General Marshall before than. We have discovered the most terrible bomb in the history of the world. It may be the fire destruction prophesied in the Euphrates Valley Era, after Noah and his fabulous Ark.

Anyway we 'think' we have found the way to cause a disintegration of the atom. An experiment in the New Mexican desert was startling - to put it mildly. Thirteen pounds of the explosive caused the complete disintegration of a steel tower 60 feet high, created a crater 6 feet deep and 1,200 feet in diameter, knocked over a steel tower 1/2 mile away and knocked men down 10,000 yards away. The explosion was visible for more than 200 miles and audible for 40 miles and more.

July 30, 1945 Truman Diary

Sent Capt. Vardaman to ship at Portsmouth, Eng. to get ready for departure to US some day soon. Secretary of Navy Joe Forestal came to breakfast with me and we discussed universal military service after the war and navy policy on office training etc.Gen. Eisenhower and son were also at breakfast with us. His boy is a nice fellow. Adm. Cochran and several other naval officers were present.

Conference is delayed. Stalin and Molotov were to call on me yesterday to discuss Polish question and Reparations. Molotov came but no Stalin. Said he is sick. No big three meeting yesterday and none today as a result of Stalins indisposition. Send him a note expressing regret at his illness. Sent Churchill a note of consolation, telling him we regreted his failure to return and wishing him a long and happy life. If Stalin should suddenly cash in it would end the original Big Three. First Roosevelt by death, then Churchill by political failure and the Stalin. I am wondering what would happen to Russia and central Europe if Joe suddenly passed out. If some demagogue on horse back gained control of the efficient Russian military machine he could play havoc with European peace for a while. I also wonder if there is a man with the necessary strength and following to step into Stalin's place and maintain peace and solidarity at home. It isn't customary for dictators to train leaders to follow them in power. I've seen no one at this Conference in the Russian line up who can do the job. Molotov is not able to do it. He lacks sincerity. Vishinsky same thing and Maisky is short on honesty. Well we shall see what we shall see. Uncle Joe's pretty tough mentally and physically but there is an end to every man and we can't help but speculate.

We are at an impass on Poland and its western boundary and on Reparations Russia and Poland have agreed on the Oder and West Niesse to the Czechoslovakian border. Just a unilateral arrangement without so much a by your lease. I don't like it. Roosevelt let Maisky mention twenty billions as reparations -- half for Russia and half for everybody else. Experts say no such figure is available. I've made it plain that the United States of America does not intend to pay reparations this time. I want the German war industry machine completely dismantled and far as U.S. is concerned the other allies can divide it up on any basis they choose.  Food and other necessities we send into the restored countries and Germany must be first lein on export before reparation. If Russian strip country and carry off population of course there'll be no reparations.

I have offered a waterway program and a suggestion for free intercourse between Central European nations which will help keep future peace. Our only hope for good from the European War is restored prosperity to Europe and future trade with them. It is a sick situation at best.

August 10, 1945 Truman Diary

Ate lunch at my desk and discussed the Jap offer to surrender which came in a couple of hours earlier. They wanted to make a condition precedent to the surrender. Our terms are 'unconditional'. They wanted to keep the Emperor. We told 'em we'd tell 'em how to keep him, but we'd make the terms.

August 10, 1945 Truman Diary

We are all on edge waiting for the Japs to answer. Have had a hell of a day.


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Document B: Excerpt from document produced during June 6, 1945 meeting of Japanese Supreme War Council entitled The Fundamental Policy to be Followed Henceforth in the Conduct of the War.

“With a faith born of eternal loyalty as our inspiration, we shall -- thanks to the advantages of our terrain and the unity of our nation, prosecute the war to the bitter end in order to uphold our national essence, protect the Imperial land and achieve our goals of conquest.”

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Document C: Excerpt from diary of Secretary of War Henry Stimson regarding meeting of General Staff (Dated entry from June 11, 1945), from Yale Library, Stimson papers.

June 11, 1945 Diary Entry:

"President Truman had sent me a letter which he had received from Herbert Hoover on the problems of the next campaign against Japan and has asked me for my opinion. I turned it over to the staff to get their reaction to it and had a talk both with [Gen. Thomas] Handy [the Army Deputy Chief of Staff] and with [Gen. George] Marshall [the Army Chief of Staff] on the subject."

[In this letter Hoover suggested an invasion of mainland Japan would cost "the lives of 500,000 to 1,000,000 American boys". General Marshall rejected this estimate on at least two occasions: in a June 4, 1945 report which stated: "the estimated loss of 500,000 lives due to carrying the war to conclusion under our present plan of campaign is considered to be entirely too high." and in a June 14, 1945 report, "the estimate of 500,000 to 1,000,000 American lives for carrying the war to a conclusion appears to deserve little consideration." (RG 107, Formerly Top Secret Correspondence of Sec. of War Stimson ("Safe File") 1940-1945, Box 8, Folder: Japan (After Dec. 7/41), National Archives].

[Hoover also suggested in his letter that surrender might be possible due to "The desire of the Japanese to preserve the Mikado [the emperor] who is the spiritual head of the nation" (Ibid.)].


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Document D: Memorandum by Manhattan Project scientist J. R. Oppenheimer, "Recommendations on the Immediate Use of Nuclear Weapons," (June 16, 1945) Top Secret Found online:

Recommendations on the Immediate Use of Nuclear Weapons

AH Compton
EO Lawrence
JR Oppenheimer
E Fermi

JR Oppenheimer
For the Panel

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, that these may be ready to use during the present war, 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 and 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 who have had the 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 the atomic power.

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Document E: General George C. Marshall quoted in John P. Sutherland, "The Story General Marshall Told Me," U.S. News and World Report 47 (November 2, 1959).

"We had to assume that a force of 2.5 million Japanese would fight to the death as they did on all those islands we [already] attacked. . . We felt this despite what [Army Air Force] generals with cigars in their mouths [an obvious reference to Curtis LeMay] had to say about bombing the Japanese into submission. We killed 100,000 Japanese in one raid in one night, but it didn't mean a thing insofar as actually beating the Japanese."


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Document F: Correspondence between Irv Kupcinet and Harry S. Truman, including draft copies of Truman’s letter, July 30 and August 5, 1963, responding to Mr. Kupcinet’s column in the Chicago Sun-Times about the dropping of the atomic bomb on Japan. Papers of Harry S. Truman: Post-Presidential Files.

Truman Memo


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Document G: Excerpt from autobiography of Admiral William D. Leahy, I Was There (1979).

"Both sides were prepared throughout the war that had just ended to unloose deadly gases, but not even the fanatical followers of Hitler and Hirohito, who committed so many other unspeakable atrocities dared use poison gas—for fear of retaliation.

To me, the atomic bomb belongs in exactly the same category.

I have admitted frankly in the preceding chapter that I misjudged the terrible efficiency of this entirely new concept of an explosive. In the fall of 1944 I held conferences with Professor Bush, Lord Cherwell, the British expert on atomic energy, and Major General Groves. They had convinced President Roosevelt and Prime Minister Churchill of the potential effectiveness of atomic energy for military purposes.

As a result, vast sums of money were appropriated to push the development with all possible speed.

In the spring of 1945 President Truman directed Mr. Byrnes to make a special study of the status and prospects of the new atomic explosive on which two billion dollars already had been spent. Byrnes came to my home on the evening of June 4 to discuss his findings. He was more favorably impressed than I had been up to that time with the prospects of success in the final development and use of this new weapon.

Once it had been tested, President Truman faced the decision as to whether to use it. He did not like the idea, but was persuaded that it would shorten the war against Japan and save American lives. It is my opinion that the use of this barbarous weapon at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender because of the effective sea blockade and the successful bombing with conventional weapons.”


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Document H. Hewlett and Oscar E. Anderson, Jr., The New World: A History of the United States Atomic Energy Commission, Volume 1, 1939/1946 (1972). Includes capital and operations costs from 1942 through 1945. Costs adjusted using a base year of 1944 (the year of highest Manhattan Project expenditures). Actual costs per facility per year are apparently unknown.

—Clinton Laboratories

Site/Project Then-year Dollars Constant 1996 Dollars
OAK RIDGE (Total) $1,188,352,000 $13,565,662,000
—K-25 Gaseous Diffusion Plant $512,166,000 $5,846,644,000
—Y-12 Electromagnetic Plant $477,631,000 $5,452,409,000
—Clinton Engineer Works, HQ and central utilities $155,951,000 $1,780,263,000
—Clinton Laboratories $26,932,000 $307,443,000
—S-50 Thermal Diffusion Plant $15,672,000 $178,904,000
HANFORD ENGINEER WORKS $390,124,000 $4,453,470,000
SPECIAL OPERATING MATERIALS $103,369,000 $1,180,011,000
LOS ALAMOS PROJECT $74,055,000 $845,377,000
RESEARCH AND DEVELOPMENT $69,681,000 $795,445,000
GOVERNMENT OVERHEAD $37,255,000 $425,285,000
HEAVY WATER PLANTS $26,768,000 $305,571,000
Grand Total $1,889,604,000 $21,570,821,000


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