This article is about the Civil War-era fort that defended Washington, D.C.. For the fort in Alabama, see Fort Williams
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.
It was named for Thomas Williams, killed at Baton Rouge, on August 5, 1862.
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.
It was built by the 2nd Connecticut Heavy Artillery Regiment. It had a perimeter of 250 yards, and space for 13 guns. 
The Fort is now a 7.80 acres (31,600 m2) Alexandria, Virginia city park, at 501 Fort Williams Parkway.