Origin - Army FC, Navy FC, Air Force FC era (?-1983)
There were ROK Army FC, ROK Navy FC, ROK Air Force FC until 1983 in Korea. ROK Marine Corps FC became ROK Navy FC in 1973. The 3 military football clubs were consolidated into one, football side of Korea Armed Forces Athletic Corps in January 1984.
Founding and Sangmu Semi-professional FC era (1984–2002)
Sangmu FC was founded on 11 January 1984, as the football side of Korea Armed Forces Athletic Corps. Although Sangmu squad was composed of professional players from K-League club, Sangmu FC competed in the Semi-professional league (present Korea National League). In 1985 Sangmu joined the K-League for the 1985 season, but spent only one year in the league before dropping out.
Sangmu's playing staff is made up of young Korean professional footballers serving their compulsory two year military duty. Fifteen players join up at the start of every season and spend two years with the side before returning to their previous professional club. Sangmu are not allowed to sign any foreign players because of their military status. The military nature of the club means that the overwhelming majority of the players are in their early 20s, and thus lack the playing experience of the opponents. As a consequence, the club has historically been underachievers in the K-League.
The reserve side, Sangmu B, competed in the K2 League from 2003 to 2005 before joining the K-League reserve league. It finished runners-up in the 2003 K2 League season, and was based in Icheon for the three years it competed at K2 level.
Once Gwangju FC was established, Gwangju Sangmu FC moved to Sangju, Gyeongsangbuk-do. So since 2011 season, the club has been known as Sangju Sangmu Phoenix FC. Club official name was changed to Sangju Sangmu Phoenix FC in January 2010.