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Lieutenant General Leslie Groves (1896-1970) was a United States Army Corps of Engineers officer and director of the Manhattan Project.

In September 1942, Groves was appointed to head the Manhattan Project with the rank of Temporary Brigadier General. As project leader, he was in charge of all of the project’s phases, including scientific, technical and process development; construction; production; security and military intelligence of enemy activities; and planning for use of the bomb.

Under General Groves’ direction, atomic research was conducted at Columbia University and the University of Chicago. The main project sites were built at Los Alamos, Oak Ridge, and Hanford. He personally selected J. Robert Oppenheimer as leader of the Los Alamos laboratory, disregarding the latter man’s Communist associations and waiving his security clearance process.

Groves was known for his critical and stubborn attitude, egotism, intelligence, and drive to achieve his goals at all costs. He continued to lead the project until 1947, when atomic energy affairs were turned over to the newly created civilian Atomic Energy Commission.

Colonel Kenneth D. Nichols, district engineer of the Manhattan Engineer District, wrote of Groves: “First, General Groves is the biggest S.O.B. I have ever worked for. He is most demanding. He is most critical. He is always a driver, never a praiser. He is abrasive and sarcastic. He disregards all normal organizational channels. He is extremely intelligent. He has the guts to make timely, difficult decisions. He is the most egotistical man I know. He knows he is right and so sticks by his decision. He abounds with energy and expects everyone to work as hard, or even harder, than he does… if I had to do my part of the atomic bomb project over again and had the privilege of picking my boss, I would pick General Groves.”

Groves’ biographer, Robert S. Norris, dubbed Groves “The Manhattan Project’s Indispensable Man.”


Early Life

Leslie Groves was born in Albany, New York on August 17, 1896. A graduate of West Point, Groves entered the Army Corps of Engineers in 1918 and was promoted several times before being named deputy to the Chief of Construction in 1940. The projects included the building of camps, depots, air bases, munitions plants, hospitals, airplane plants, and the massive Pentagon, which he completed building in less than a year and a half. Groves oversaw a million men and spent $8 billion on Army construction with a peak month in July 1942 of $720 million, the equivalent of fifteen Pentagons. Groves’ proven record of managing complex undertakings made him a logical choice to lead the Manhattan Project.


Later Years

Groves was promoted to Temporary Lieutenant General in January 1948 and retired a month later on February 29. From 1948 to 1961, he was vice president of the Sperry Rand Corporation.  He also served as president of the West Point alumni association.  Groves died in Washington, DC on July 13, 1970.

Leslie R. Groves's Timeline
1896 Aug 17th Born in Albany, New York.
1918 Graduated 4th in his class from West Point.
1922 Feb 10th Married Grace Wilson.
1939 Jul Posted to the War Department General Staff in Washington, DC and named special assistant for construction to the Quartermaster General.
1940 Nov Took command of the Fixed Fee Branch of the Construction Division and promoted to Colonel.
19411942 Oversaw construction of the Pentagon in Arlington, VA.
1942 Sep 17th Notified at 10:30 a.m. by Gen. Brehon Somervell that his assignment overseas was cancelled and that he would take another assignment - command of the Manhattan Engineer District.
1942 Sep 18th Bought 1250 tons of high quality Belgian Congo uranium ore stored on Staten Island.
1942 Sep 19th Selected Oak Ridge, TN as the site for the pilot uranium enrichment plant. Purchased Site X or 52,000 acres of land on the Clinch River.
1942 Sep 19th At Groves' insistence, the Manhattan Project is granted approval by the War Production Board to use the highest emergency procurement priority in existence (AAA) when needed.
1942 Sep 23rd Promoted to Brigadier General.
1942 Oct Puts DuPont in charge of the plutonium production project.
1942 Oct 5th Visited the Chicago Met Lab and meets the key scientists, including J. Robert Oppenheimer. Ordered key engineering decisions for plutonium production, under debate for months, be made in 5 days.
1942 Oct 15th Asked J. Robert Oppenheimer to head Project Y, planned to be the new central laboratory for weapon physics research and design.
1942 Nov 25th Selected Los Alamos, NM as the site for a scientific research laboratory, codenamed "Project Y.
1943 Jan 16th Selected Hanford, WA as the plutonium production site.
1943 Aug Due to lagging progress on gaseous diffusion, and continuing uncertainties about the required amount of U-235 for a bomb, Groves decided to double the size of the Y-12 Plant.
1944 Jan Problems with developing suitable diffusion barriers led Groves to switch planned production to a new type of barrier, creating months of delays in equipping the K-25 Plant for operation.
1944 Jan Groves and Oppenheimer decided to plan for a fission bomb test (none was envisioned before this). Groves stipulated that the active material must be recoverable if a fizzle occurs, so the construction of Jumbo, a 214 ton steel container (25 ft x 12 ft), is authorized.
1944 Jun 18th Contracted to have the S-50 Plant, intended for liquid thermal diffusion uranium enrichment, built at Oak Ridge, TN in no more than three months.
1945 Apr 25th Groves and Secretary of War Henry Stimson gave President Harry Truman his first in-depth briefing on the Manhattan Project. Truman authorizes Groves to continue with the project and agrees to create a committee to advise the president on using the bomb.
1945 Jun 18th Submitted the target selections to General George Marshall.
1945 Jun 27th Met with Oppenheimer and Deak Parsons to plan delivery of atomic bombs to the Pacific theater.
1945 Jul 16th To his immense relief, witnessed the Trinity test.
1945 Jul 24th Drafted the directive authorizing the use of the atomic bombs as soon as bomb availability and weather permit. It lists the following targets in order of priority: Hiroshima, Kokura, Niigata, and Nagasaki. This directive constitutes final authorization for atomic attack, no further orders are issued.
1945 Aug 9th Learned of the successful bombing of Hiroshima. Groves' role in the project is featured in the press, and his family and friends learn for the first time about his work.
1945 Aug 11th Reported that the second plutonium core would be ready for shipment on August 12 or 13, with a bombing possible on August 17 or 18. Decided to delay shipment of core.
1947 Jan 1st The US Atomic Energy Commission takes over responsibility for nuclear power and weapons.
1947 Feb 28th Appointed chief of the Armed Forces Special Weapons Project to control the military aspects of nuclear weapons.
1948 Feb 29th Retired from the Army.
19481961 Vice President of Sperry Rand Corporation.
1962 Published memoir of his Manhattan Project work, "Now It Can be Told.
1970 Jul 13th Died in Washington, DC.

General Leslie R. Groves at work on the telephone

General Leslie R. Groves and J. Robert Oppenheimer after the successful Trinity test

General Groves and David Lilienthal discussing the transfer of atomic energy affairs to the AEC

General Groves playing tennis as a young man, during an Army posting in Nicaragua

General Leslie R. Groves

General Leslie R. Groves

Groves and Farrell

Leslie Groves, Richard Tolman and Robert Bacher

General Leslie Groves addressing a crowd at Hanford

General Groves pinning an award on Enrico Fermi 

General Groves with Patricia Cox Owen and her husband Claude. Photo courtesy of the Patricia Cox Owen Collection.

Donna Reed and Leslie Groves. Photo courtesy of the Patricia Cox Owen Collection.

Patty Cox Owen and General Groves. Photo courtesy of the Patricia Cox Owen Collection.

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