DAHLONEGA — More than 60 years ago, while America was fighting a war in Korea, the U.S. Department of Defense turned to the North Georgia mountains to start a training phase for one of its most elite units, the Army Rangers. Tucked away amid Georgia pines, curvy roads and the Etowah River headwaters, Camp Frank D. Merrill still carries out that role in a 293.2-acre corner of the Chattahoochee-Oconee National Forests. It’s hard to reach, several miles outside of Dahlonega in Lumpkin County, but not unreachable, as attested to by hikers and other outdoor lovers who roam the area.