Melissa Haneline/The Post and CourierJai Cassidy-Shaman handles two Revolutionary War letters Tuesday bought at auction by the South Carolina Confederate Relic Room and Military Museum in Columbia. Like so many first-time visitors to the Lowcountry, Charles Campbell was enchanted. In a letter to his father back home in Britain, Campbell gushed about the natural beauty of the Holy City in spring. Captain's letter "Charlestown is a handsome and well built town situated on the extremity of a tongue of land formed by two large & navigable rivers, Cooper and Ashley;" he wrote, "it lays open to the sea, and...