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Setting the Test Date, July 2, 1945

Groves office diary, July 2, 1945, page 1 - small image

Source: U.S. National Archives, Record Group 200, National Archives Gift Collection, “Diary of Lt. Gen. Leslie R. Groves,” Microfilm roll #2.

The date of the first test of the atomic bomb, code-named Trinity, was set for political reasons. President Truman had delayed his meeting with Stalin until the atomic bomb could be tested. These excerpts from General Groves’ office diary show Groves informing Robert Oppenheimer that the test date was being set by “the upper crust.”

An excerpt on the same subject, from Robert Oppenheimer’s later Security Board testimony, is also included.

Images of three pages of Groves’ office diary for July 2 are included below the transcription.

Groves Office Diary

Groves’ diary, which was kept by his secretary, was deliberately cryptic. This is the cast of characters:

Bundy - Harvey Bundy, Assistant to Secretary of War Stimson
Dr. Conant (also Uncle Jim) - James B. Conant, Chairman of the National Defense Research Committee (NDRC)
Mr. Harrison - George L. Harrison, Assistant to Secretary of War Stimson
Oppy or Oppie or Dr. O or JRO - Robert Oppenheimer, Director of Los Alamos
Tolman - Richard C. Tolman, scientific advisor to General Groves

Monday, July 2, 1945

12:50 pm Gen Groves called Dr. Oppenheimer, Santa Fe. Oppy said they discussed Mr. CT for the 19, 20, and 21, and therefore scheduled it for the 17th. Dr. O said that the 14th was possible but was not sure. Dr. O thought the wisest thing was to schedule it for the 17th in which case they would be fairly sure of getting the thing done within a few days of that day. GG asked what the prospects were on that and Dr. O said that they were very high and ought to be able to go fishing on the morning of the 18th. Dr. O said that by that time there would be no delay nor would the material be sitting around which would be a distinct disadvantage. The 3 days involved is 3 days in which everyone could take advantage of. This would cause what would have been a frantic one to a reasonable one. GG said that he did not like the idea of a later date because of the various things that were involved. GG also said that it was extremely important that it be completed by the earlier date because of the various things that were involved... Dr. O said that he had talked with the rest of the men involved and they believed that the later date would be better. GG then told Dr. O the reason why the earlier date had to be. Dr. O said they would meet the earlier date but it went against his own feeling but if the Gen wanted it that way they would do it...

3:30 pm Gen Groves called Dr. Conant, Ipswich, Mass re conversation with JRO. Dr. Conant said that the Gen had done right to stay along with the earlier date. Dr C suggested that GG get in touch with Tolman and request him to exert his efforts in getting Oppy and the men persuaded to the earlier date. Dr. C said that the Gen could tell Tolman that he agreed to the earlier date and did not see how they could predict weather so far in advance. Dr C said that they did not give one good reason why they could not meet the earlier date.

4:30 pm Gen Groves called Mr. Harrison with respect the first date. Gen Groves said that he had a very strong urging from the people in charge at the site to postpone the date four days. Gen Groves said that he had told Oppy that they had to have the first date because of things beyond his control. Mr. Harrison said that was a sound decision. GG said that he had told Dr. O that he would review the situation some more. Mr. H then told Mr. Bundy of the situation and Mr. B said that other things were involved and the earlier date was the one.

5:45 pm Dr. Tolman called Gen Groves from Y re: GG told Tolman that he wanted to talk to him about what he had told director in previous telephone conversation. GG said that since he had talked to Y the upper crust wanted it as soon as possible. So to stress the urgency of having it done the 14th. GG said he was not in agreement with the upper crust. GG said he wanted Tolman to stress to the people out there that he was not needling them but there was nothing he could do about it. Tolman transferred GG to Oppie. GG told Oppie since his talk with him earlier he talked with a number of people, also called Uncle Jim. GG told Oppie this afternoon he talked with alternate chairman and associate and also again with Uncle Jim. They wanted earlier date - 14th. Oppie told GG that material has not been coming in from Nichols as should and considerable poorer quality. Oppie said he didn’t believe it was anybody’s fault. GG stressed on Oppie the importance of trying to arrange for the 14th and he also told Oppie to tell his people that it wasn’t his fault but came from higher authority.

Oppenheimer testimony

Robert Oppenheimer later discussed the reason for the test date in his Security Hearing in 1954. Oppenheimer was being questioned by his attorney Lloyd Garrison:

Q: As the work progressed, you began to get goals and deadlines, I suppose, against which to produce the bomb, if you could?

A: The deadline never changed. It was as soon as possible. This depends on when we were ready, when the stuff was ready, and how much stuff we needed.

Q: Wasn’t there a particular effort to get it done before the Potsdam Conference?

A: Yes, that was of course quite late. After the collapse of Germany, we understood that it was important to get this ready for the war in Japan. We were told that it would be very important — I was told I guess by Mr. Stimson — that it would be very important to know the state of affairs before the meeting at Postdam at which the future conduct of the war in the Far East would be discussed.

Q: Discussed with the Russians?

A: I don’t want to overstate that. It was my understanding, and on the morning of July 16, I think Dr. Bush told me, that it was the intention of the United States statesmen who went to Potsdam to say something about this to the Russians. I never knew how much. Mr. Stimson explained later that he had planned to say a good deal more than what was said, but when they saw what the Russians looked like and how it felt, he didn’t know whether it was a good idea. The historical record as it is published indicates that the President said no more than we had a new weapon which we planned to use in Japan, and it was very powerful. I believe we were under incredible pressure to get it done before the Potsdam meeting and Groves and I bickered for a couple of days...

Source: United States Atomic Energy Commission, In the Matter of J. Robert Oppenheimer: Transcript of Hearing Before Personnel Security Board, Washington D.C., April 12, 1954, through May 6, 1954, pp 31-32.

Groves office diary, July 2, 1945 - page 1

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Images of pages 3 to 5 not included here.

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