Greenville is a city in Darke County, Ohio, United States. The population was 13,227 at the 2010 census. It is the county seat of Darke County.
Greenville is the historic location of Fort Greene Ville,(Greenville was never known as a fort. Its original name was The Camp on the West Branch of the Stillwater River.) a pioneer fort built under General Anthony Wayne's command, at over 55 acres (220,000 m2) this was the largest wooden fortification ever built. It was here that the Treaty of Greenville was signed on August 3, 1795, bringing peace to the area and opening up the Northwest Territory for settlement. Fort Greene Ville was named for Wayne's fellow General Nathanael Greene.
Greenville is located at 40°6′9″N 84°37′41″W / 40.1025°N 84.62806°W / 40.1025; -84.62806 (40.102474, -84.627985).