 Army of the Republic of Vietnam (ARVN) influence extended south to the Nông Sơn coal mines in the narrow canyon of the Sông Thu Bồn, about 10 kilometers from the district seat.Here at a place called Da Trach, not far north of the major operating base of the People's Army of Vietnam (PAVN) 2nd Division, the ARVN maintained a garrison with outposts manned by Regional Force (RF) units and Popular Force (PF) platoons.Duc Duc was the other principal entrance to the Quảng Nam lowlands from the PAVN-held highlands of Quảng Nam and Quảng Tín Provinces.