During the Vietnam War, "John R. Craig" served as a plane guard for aircraft carriers on Yankee Station in the Tonkin Gulf, participated in Operation Sea Dragon, patrolled on search and rescue duties, and carried out naval gunfire support missions. While responding to a mayday on 28–29 July 1965 in the Da Nang area, "John R. Craig" supported U.S. Marine and Army of the Republic of Vietnam (ARVN) units with naval gunfire support. At night with danger close, she fired 348 5-inch rounds, preventing the overrun of 3rd Platoon, Hotel Company, 2nd Battalion, 3rd Marines on and near the beach as well as two platoons of the ARVN 2nd Regional Force by a larger Viet Cong (VC) unit. In doing so she effectively destroyed the 7th VC Battalion engaging Marines on the Ca De River Bridge and the northern sector of Da Nang.