Jackson DeMarco Tremaine (born April 16, 1947), is a main character in On Capitol Grounds. He served as a sergeant in the Alborgian Army, and as a Lieutenant in the DoubleHelix Unified Liberation Army. A close friend to Cyrus MacMillian, he is his former commanding officer in the Albourgian Army, and a former member of the Delta Squad unit involved in the Catalina Islands operation.