General Leslie R. Groves: A lifetime of construction and service

From his early Army years at West Point to his leadership of the Manhattan Project, Gen. Leslie R. Groves is remembered for a lifetime of extraordinary military service.

By Renae Mitchell | October 10, 2023

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“I believe that Los Alamos exists because of Groves,” said Lab historian Roger Meade. “He hired directors [J. Robert] Oppenheimer, who created and built the wartime lab, and [Norris] Bradbury, who kept the lab relevant after the end of the war and laid the foundation for its permanence.”

Early military influence

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Gen. Leslie Groves’s badge photo from the Manhattan Project–era lab in Los Alamos. His and other badge photos are part of the collections of the Lab’s National Security Research Center.

Military leadership seemed to be in Groves’s blood and his destiny. In 1896, the year Groves was born, his father transitioned from a full-time Presbyterian pastor to a military chaplain. Growing up on military installations and witnessing his father’s dedicated service were influential on Groves’s educational and professional decisions. 

In his book Now It Can Be Told: The Story of the Manhattan Project (1962), Groves reflected on how he “came to know many of the old soldiers and scouts who had devoted their active lives to winning the West,” whose stories left him “somewhat dismayed, wondering what was left for me to do now that the West was won.” However, after World War I, Groves’s life path became clear. 

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Gen. Leslie Groves was the leader of the Manhattan Project, the U.S. government’s top-secret effort to build atomic weapons during World War II. Among other decisions, Groves helped select Los Alamos as the site for the clandestine lab and hired physicist J. Robert Oppenheimer as its first director.

Starting a military career

At the U.S. military academy West Point, Groves’s education was fast-tracked through a War Emergency Course because of the United States’ entry into World War I. He later graduated from the Army Engineer School, Command and General Staff School, and Army War College. 

After serving on several military bases at home and abroad, Groves joined the War Department General Staff in Washington, DC, to direct the location and construction of a site for training and mobilizing Army personnel. He then led the construction of the world’s largest office building at the time: the headquarters for the U.S. Department of Defense and a symbol of the military, what would come to be known as the Pentagon. Construction of the Pentagon began in 1941 and was completed in 1943. These large planning and construction projects helped prepare him for what would be the biggest project of his life. 

Leading the Manhattan Project

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Gen. Leslie Groves studies a map of the Pacific, where fighting continued against the Japanese as Los Alamos scientists worked to create the first atomic bombs and end World War II.  

The Manhattan Project had begun in August 1942, but many of those involved found progress too slow and inefficient for such an urgent objective—the development and production of the world’s first atomic bomb. The project needed someone who would shepherd its construction and advancement more aggressively, and the name that came up in discussions was Leslie Groves. 

The pace that Groves set for the construction of the Los Alamos wartime lab was ambitious indeed, and this efficiency earned him the reputation of having “no time for the subtleties of diplomacy . . . By temperament and training, he was an authoritarian,” according to American Prometheus, which also noted that Groves’s aide Col. Kenneth D. Nichols said, “He has the guts to make timely, difficult decisions . . . I hated his guts and so did everybody else, but we had our form of understanding.” 

Choosing Oppie and Los Alamos

Groves needed a scientist with a breadth of physics knowledge, rather than a specialization, to oversee the scientific administration of the laboratory. Groves chose physicist J. Robert Oppenheimer despite opposition from the Manhattan Engineer District (MED) and Military Policy Commission, which expressed numerous concerns over Oppenheimer’s past associations with friends and family members who had ties to the communist party. Additionally, as Groves states in his book, “Oppenheimer had two major disadvantages—he had had almost no administrative experience of any kind, and he was not a Nobel Prize winner.” 

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This memo from Gen. Leslie Groves to the chief of staff details the availability of a third weapon, following the U.S. bombings of Hiroshima and Nagasaki. However, Japan surrendered unconditionally and no other bombs were deployed.

Groves was certain of his choice, though, and issued the following letter: “In accordance with my verbal directions . . . it is desired that clearance be issued for the employment of Julius Robert Oppenheimer without delay, irrespective of the information which you have concerning Mr. Oppenheimer. He is absolutely essential to the project.” 

Groves’s instincts were correct. Oppenheimer’s role became one of many decisions Groves made that proved instrumental to the Manhattan Project’s success. Another was choosing the site of Los Alamos. 

Groves drew on his experience in construction and site preparation to make the critical decision of where the secret scientific laboratory, called Project Y, would be located. After discussions with Oppenheimer, Groves sought a location that was isolated enough for scientists to collaborate freely but could support the construction of critical research and development facilities. With agreement from the search committee, Groves settled on a rural area in the northern New Mexico mountains, inhabited by a few homesteaders and a boys’ boarding school. 

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Seated, from left: second Lab Director Norris Bradbury; Gen. Leslie Groves; and Eric Jette, division leader for Chemistry and Metallurgy.

Deploying the atomic bombs

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“Oppenheimer had told me that he wanted to leave [the Los Alamos lab] as soon as he could [after the war ended], and we discussed a possible successor for him,” writes Groves in Now it Can Be Told. “After much thought and considerable discussion with Oppenheimer and others I asked Dr. Norris Bradbury [pictured here talking with Groves] to take the position. Bradbury had . . . played an important part in the development of the gun-type bomb. Also, he was a Navy reserve officer, a circumstance I thought would help him in maintaining smooth relations between the civilian scientific staff and the military administrative officers.”

Once the bombs had been successfully developed, there was another critical decision to make. Groves consulted with members of the U.S. administration and a Target Committee, which included other members of the Manhattan Project, to discuss the where, when, and why of potential locations to drop the bombs and end the war. Groves never wavered from this objective, recalling in his book, “In such a climate, no one who held a position of responsibility in the Manhattan Project could doubt that we were trying to perfect a weapon that, however repugnant it might be to us as human beings, could nonetheless save untold numbers of American lives.” 

Five sites were chosen within Japan, to be bombed consecutively until a declaration of peace could be made. “I had set as the governing factor that the targets chosen should be places the bombing of which would most adversely affect the will of the Japanese people to continue the war,” Groves wrote. “Beyond that, they should be military in nature.” Once Hiroshima and then Nagasaki had been bombed, the U.S. military began preparations for a third site. However, the emperor of Japan agreed to a peace treaty before the third bomb could be delivered. 

With the official end of World War II on September 2, 1945, Groves received numerous awards and commendations, including the Distinguished Service Medal, Commander of the Order of the Crown from Belgium, and Companion of the Order of the Bath from Britain. These awards recognized Groves’s accomplishments as well as the military allied relationship between the United States and other countries. 

After the Manhattan Project

Groves relinquished responsibility for the MED and Los Alamos in 1947. He went on to pursue a civilian career but maintained ties with the military. He was promoted in retirement to lieutenant general and served as president of the West Point alumni organization, among other distinctions. 

Groves died from heart disease at the age of 73 and is interred at Arlington National Cemetery. 

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Known as an unlikely pair, J. Robert Oppenheimer and Gen. Leslie Groves formed a successful partnership based in mutual respect. The two stand in perpetual conversation in this memorial located in downtown Los Alamos.