The 21st Signal Brigade is a major subordinate command of the 7th Signal Command (Theater). The original 21st Signal Group was constituted on 22 June 1965 in the Regular Army as the Headquarters and Headquarters Detachment, 21st Signal Group and activated on 1 September 1965 at Fort Bragg, North Carolina. The unit was headquartered at Nha Trang, South Vietnam and provided area signal communications support throughout 10,000 square miles of area I and II of the Corps tactical zones. The unit also saw action throughout thirteen campaigns during the Vietnam War and received the Meritorious Unit Commendation. The Unit went inactivated on 27 November 1971 at Fort Lewis, Washington. Then on 16 October 2003 the Unit was reactivated and designated the 21st Signal Brigade, headquartered at Fort Detrick, Maryland.
The 21st Signal Brigade’s mission is to provide Command, Control, Communications, and Computers (C4) systems support to the President, Secretary of Defense, Joint Chiefs of Staff, Department of Defense, Combatant Commanders and other Federal Agencies. To establish, operate, protect, and sustain the Army's CONUS (Continental United States) strategic portion of the Global Information Grid. To protect and provide for the well-being of our people. The Brigade is headquartered at Fort Detrick, Maryland and has three subordinate battalions: the 114th Signal Battalion located at Raven Rock Mountain Complex in Adams County, Pennsylvania; the 302d Signal Battalion headquartered at Fort Detrick, Maryland; and the 56th Signal Battalion headquartered at Joint Base San Antonio, Texas.