 From 1 to 7 December 1968, "Terrell County" conducted general drills and gunnery exercises before beaching at Vũng Tàu to load ammunition.On 10 December 1968, she relieved "Washoe County" as support LST for Task Force 115 on Operation Market Time, the interdiction operation attempting to interrupt North Vietnamese logistics operations in South Vietnamese coastal waters.On 1 January 1969 "Terrell County", still supporting Operation Market Time, was assigned additional duty as support ship for the fast Fast Patrol Craft (PCF) boats engaged in riverine operations off the lower Cà Mau Peninsula.