Five years later, the Battalion was reactivated on 20 June 1951 at Camp Pendleton, California and was assigned to the 3rd Marine Division. In August 1953, 1st Battalion 12th Marines deployed to Camp Mcnair, Japan and redeployed to South Camp Fuji, Japan during March 1956. During March and April 1965, the battalion was called upon to deploy to the Republic of Vietnam. They participated in the Vietnam War from April 1965 to September 1969, operating from Phu Bai, Danang, Cam Lộ, Khe Sanh and Camp Carroll. The battalion after the Vietnam war was reduced to cadre status.