Saluting the Engineer Who Oversaw Pentagon Construction and the Manhattan Project

September 1, 2015
Lt. Gen. Leslie Groves

August marked the birth month of Lt. Gen. Leslie Groves, who supervised construction of the Pentagon and directed the Manhattan Project’s development of the atomic bomb during World War II.

Leslie Richard Groves Jr. was born Aug. 17, 1896, in Albany, NY. In 1916, after three years of studying at the University of Washington and Massachusetts Institute of Technology, Groves fulfilled his ambition to enter the United States Military Academy at West Point. He graduated fourth in his class in 1918, and was commissioned in the Engineers School, Camp Humphreys (now Fort Belvoir, VA), where he took courses, including a French educational tour of European World War I battlefields.

During the 1920s, Groves’ accomplishments included constructing a trail from Kahuku to Pupukea in Hawaii, opening the channel at Port Isabel, TX, supervising dredging operations in Galveston Bay, assisting in Vermont during the 1927 New England Flood, and conducting a survey for the Inter-Oceanic Nicaragua Canal. In 1931, following an earthquake in Nicaragua, Groves took over responsibility for Managua’s water supply system, for which he was awarded the Nicaraguan Presidential Medal of Merit.

In 1931, Groves was attached to the Office of the Chief of Engineers. He graduated in 1936 from the Command and General Staff School in Fort Leavenworth, KS, and from the Army War College in 1939, after which he was assigned to the General Staff in Washington, DC. A year later Groves became special assistant for construction to the Quartermaster General, tasked with inspecting construction sites and monitoring their progress.

In August 1941, Groves was given responsibility for the construction of the Pentagon. The chief of the Construction Division’s Design and Engineering Section, along with George Bergstrom, a former president of the American Institute of Architects, had designed an office complex to house the War Department’s 40,000 staff together in one building. The five-story, five-sided structure was 5,100,000 square feet, making it the largest office building in the world, almost twice the square footage of the Empire State Building. Bergstrom became the architect-engineer with Groves’ assistant, Capt. Clarence Renshaw, in charge of construction, both reporting to Groves.

The soil conditions and topography of the Pentagon site, located on the Potomac River floodplain, presented challenges to engineers. Two retaining walls were built to compensate for the 30 feet in elevation variation across the site, and cast-in-place piles were used to contend with the soil conditions. Architectural and structural design work proceeded simultaneously with construction. Groundbreaking was held on Sept. 11, 1941, a month before initial drawings were provided. Because of pressing needs brought on by World War II, people started working in the Pentagon before it was completed. The Pentagon was formally completed on Jan. 15, 1943, after approximately 16 months of construction, at a total cost of $83 million.

In September 1942, Groves was placed in charge of what became known as the Manhattan Project. The Manhattan Engineer District was established by the Chief of Engineers as the Army component of a research-and-development project that produced the first atomic bombs during World War II. The project designation, “Manhattan,” gradually superseded the official codename for the entire project, “Development of Substitute Materials.”

Basic atomic bomb research was carried out mainly at Columbia University and the University of Chicago. As project director, Groves was in charge of all phases of the project: scientific, production, security, and planning for use of the bomb. Under Groves’ direction, project plants were established at Oak Ridge, TN, Hanford, WA, and the secluded Los Alamos installation in New Mexico. Groves continued to head the atomic establishment created during wartime until January 1947. He was then named the Chief of the Army’s Special Weapons Project.

Groves retired in February 1948, a month after his promotion to lieutenant general. From that time until 1961, he worked as vice president of Sperry Rand Corporation. He also served as president of the West Point Alumni Association.

His book, Now It Can Be Told, The Story of The Manhattan Project, was published in 1962.

Groves died of heart disease on July 13, 1970, and is buried in Arlington National Cemetery.

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