Camp Carroll, an artillery firebase halfway between the Laotian border and the coast, was the linchpin of the South Vietnamese northern and western defense line and was the strongest obstacle to the North Vietnamese before Quảng Trị City. On 2 April, Colonel Pham Van Dinh, commander of the 56th ARVN Regiment, surrendered the camp and his 1,500 troops with barely a shot being fired. Later in the day, ARVN troops abandoned Mai Loc, the last western base. This allowed North Vietnamese forces to cross the Cam Lộ bridge, 11 kilometers to the west of Đông Hà. PAVN then had almost unrestricted access to western Quảng Trị Province north of the Thạch Hãn River.