The 18th Infantry Regiment was originally activated as the 18th Regiment on November 20, 1948 at P'ohang and was first commanded by Lt. Col Ch'oi Sok. The unit was not initially assigned to any division.
On August 4, 1949 the 2nd Regiment and 18th Regiment defended against a North Korean attack in the Kuksa-bong and Hill Ch'ungmu area. The units were able to repulse the initial attacks and the North Korean invasion was considered a disaster.
The 18th replaced the 26th in 1951.