DURHAM, N.C. The murderous attack on four American civilians in Falluja, Iraq, brought home gruesome images of charred bodies dangling from a bridge over the Euphrates River. It also introduced Americans to a company few had heard of: Blackwater USA, which was providing security for food delivery convoys when its employees were ambushed. Blackwater, which operates from a 5,200-acre training ground in the Great Dismal Swamp of North Carolina, is a private military firm that provides an array of services once performed solely by military personnel. The company trains soldiers in counterterrorism and urban warfare. It also provides the American...