In September 1942, Compton asked a physicist, Martin D. Whitaker, to form a skeleton operating staff for X-10. Whitaker became the inaugural director of the Clinton Laboratories, as the semiworks became officially known in April 1943. The first permanent operating staff arrived from the Metallurgical Laboratory in Chicago in April 1943, by which time DuPont began transferring its technicians to the site. They were augmented by one hundred technicians in uniform from the Army's Special Engineer Detachment. By March 1944, there were some 1,500 people working at X-10.