On 4 June 1951 the Regiment was brought out of reserve to join the 1st Marine Division in an assault on the PVA/KPA main line of resistance along a mountain range extending from Yanggu to Hill 1316 (Daeamsan). The area was defended by a regiment of the KPA 12th Division with orders to hold the position until death. from 4 to 9 June the Regiment fought the KPA making limited progress. Finally on 10 June the Regiment commander Colonel Kim Tae Shik decided to make a night attack on the KPA positions. Launched at 02:00 on 11 June the attack caught the KPA unprepared and the Marines quickly overran Hill 1122 and the rest of the ridgeline.: Following the capture of Daeamsan the Marines continued to push against the PVA/KPA to obtain better positions. On 15 June the 2nd KMC Battalion attacked north to Hill 1304 which it captured the next day. The 3rd KMC Battalion moved northwest and captured Dusol-san () following which they dug in. On 7 July the Regiment was ordered to take Daeusan (), beginning their attack on 8 July. After suffering over 220 casualties the attack was called off on 12 July.: