The North Anna River is a principal tributary of the Pamunkey River, about 62 miles (100 km) long, in central Virginia in the United States. Via the Pamunkey and York rivers, it is part of the watershed of Chesapeake Bay. The river was the site of the Battle of North Anna during the American Civil War. According to the Geographic Names Information System, the river has also been known as "Northa-Anna" and as the main stem of the Pamunkey River.