From 21 January 1968 the 26th Marines were under siege at Khe Sanh until the conclusion of Operation Pegasus on 14 April 1968 and were replaced by the 1st Marines on 15 April 1968 with the battalion flying to Quang Tri Combat Base. The 26th Marines was transferred from the operational control of the 3rd Marine Division to the 1st Marine Division on 18 May 1968. From 26 May to 6 June the battalion participated in Operation Allen Brook. The battalion then joined Operation Mameluke Thrust on 7 June. On 22 July the battalion was moved north to Phu Bai to replace the 5th Marine Regiment conducting Operation Houston. On the conclusion of Operation Houston on 12 September the 26th Marines were moved south to the Da Nang tactical area of responsibility (TAOR).