Signal Hill is a historic Confederate Army military site in Prince William County, Virginia. It is from this location, a signal station atop the hill, that Confederate observers in 1861 spotted Union Army troops attempting to cross Sudley Ford. The Confederate response to this maneuver began the First Battle of Bull Run. Part of Signal Hill is now part of a public park owned by the city of Manassas Park; the rest is part of a preservation area belonging to a neighborhood association. The site was listed on the National Register of Historic Places in 1989. See also National Register of Historic Places listings in Prince William County, Virginia References National Register of Historic Places in Prince William County, Virginia 1861 in Virginia Virginia in the American Civil War Manassas Park, Virginia