Fort Williams was a timber and earthwork fortification constructed in Alexandria, Virginia as part of the defenses of Washington, D.C. during the American Civil War. Built in the weeks following the Union defeat at Bull Run, Fort Williams was situated on north of Hunting Creek, and Cameron Run, (which feeds into it), near Vaucluse (plantation). From its position on Quaker Lane, one of the points west of Alexandria, the fort overlooked the Orange and Alexandria Railroad, the Little River Turnpike, and the western approaches to the city of Alexandria, the largest settlement in Union-occupied Northern Virginia.