Gavin Hadden was an American civil engineer who served as special assistant to General Leslie R. Groves during the Manhattan Project.
Born in New York, New York, Hadden received an A.B. degree from Harvard in 1910 and a civil engineering degree from Columbia University in 1912. Later that year, he joined the firm Barclay Parsons & Klapp. In 1917, Hadden was commissioned as a First Lieutenant of Engineers in the United States Reserve Corps and ordered into active service. After training at the Engineer Officers’ Training Camp in Bellevoir, Virginia, and a temporary assignment at Camp Lee, Hadden sailed for France in January 1918. While overseas, Hadden worked as an assistant to Major General W. C. Langfitt, who commanded the American troops working with British forces to build bridges and railroads. After falling ill, Hadden was sent back to the United States, where he was honorably discharged in 1919. After recovering, Hadden opened his own civil engineering office in New York City. During this time, he helped design a number of stadiums, including those at Cornell, Brown, and Northwestern.
Return to the Military
From 1940 until his death in 1956, Hadden worked for the War Department, which later became the Department of Defense. He served as special assistant to General Groves, and thus was a part of the Manhattan Project from the very beginning. He aided Groves in paperwork and kept his records. He was also the official historian of the Manhattan Project. The classified Manhattan District History was prepared after the war under his editorship, and “intended to describe, in simple terms, easily understood by the average reader, just what the Manhattan District did, and how, when, and where.”