Union Forge. Site of a charcoal iron forge begun about 1782 by Curtis Grubb, owner of Cornwall Iron Furnace; a major user of Cornwall iron. Such forges transformed brittle pig iron into workable wrought iron. Union Forge included 1,000 acres of land, blacksmith and carpenter shops, a grist mill, and several houses. Under different owners, the forge was in regular operation until 1868. By then, rolling mills were displacing forges as refiners of iron.