The Senate appropriated an additional $3 million for expansion of the base in September 1951. The Peterson Air Force Base, which became inactive in 1949 when the 15th Air Force was moved to the March Air Force Base, was activated when the Ent Air Force Base opened. At the same time, the 4600th Air Base Group was activated to provide support for Ent. The funding was part of a military expansion initiative for the Ent Air Force Base, Fort Carson, and Peterson Air Force Base, all in Colorado Springs, Colorado. Much of the construction at Ent was for additional residential facilities. The Air Defense Command began 24-hour Ground Observer Corps operations on 14 July 1952. Starting September 1953, the base was the headquarters for the Army Anti-Aircraft Command.