July 24, 2023

Marshall, Groves, and the Atomic Bomb

What did an explosion in the New Mexico desert and a secret program have to do with the Army Chief of Staff nearly 2,000 miles away in Washington, D.C.? Find out on The Paper Trail, a series highlighting documents and photos from the George C. Marshall Foundation archives.

This project was so secret that for a while, information was not even shared with British Prime Minister Churchill. It was called the “Manhattan Engineer District,” after the location of their offices in New York City. The project stemmed from information that the Germans had a nuclear weapons program. The United States gathered scientists and technicians, led by Maj. Gen. Groves (who reported to Gen. George Marshall) to ensure that the United States developed a weapon first. The engineering of such a weapon took place at Los Alamos, guided by theoretical physicist Dr. J. Robert Oppenheimer.

The first nuclear device tested, nicknamed “Gadget,” had a solid 35-pound plutonium core, and used an implosion to initiate the nuclear fission reaction. The bomb needed to be tested, and the attempt to explode Gadget, in a test named “Trinity” by Oppenheimer after a John Donne poem, was scheduled. A half hour before sunrise on July 16, 1945, in Bingham, N.M, Gadget was detonated from atop a 100-foot steel tower.

In his July 18, 1945 report to Secretary Stimson, housed in the GCMF Archives, Groves stated “a lighting effect within a radius of 20 miles equal to several suns in midday. A massive cloud was formed which surged and billowed upward with tremendous power, reaching the substratosphere at an elevation of 41,000 feet,” and that the “steel from the tower was evaporated.” Groves commented that “I no longer consider the Pentagon a safe shelter from such a bomb.” Although the test of the first nuclear explosion was a success, Groves closed his report to Secretary Stimson, “we are all full conscious that our real goal is still before us.”

On August 6, 1945, an atomic bomb was dropped on Hiroshima, Japan. Another was dropped three days later on Nagasaki. A third bomb was also prepared for Kyoto. In his commentary regarding this memo given to General Marshall on August 10, 1945, Groves remarks that “I recommended orally that I be authorized to delay the shipment of the fissionable material for the third bomb from the United States in order that the Japanese would have an opportunity to surrender. I did not want future anti-American propagandists to accuse us of wanting to inflict unnecessary punishment on the Japanese. A delay until noon of 13 August was approved by General Marshall, who then added his written note at the bottom of my memorandum.”

“It is not to be released over Japan without express authority from the President. G. Marshall.”

“When the deadline came there was still no Japanese surrender. Neither General Marshall nor Secretary Stimson was available. I discussed the problem with the Deputy Chief of Staff, General Handy. Neither of us felt that he could authorize me to further delay the shipment. I then made my decision. I asked General Handy to inform General Marshall that I was exceeding my instructions and in the absence of any word from him would not ship any fissionable material for the third bomb until I could see him.”

“Some days later General Marshall told me how glad he was that I had taken the action I had.”


Melissa Davis can be contacted at [email protected] for research requests.

Music: Rest You Sleeping Giant – End of Winter