Following the end of the Civil War, Fort Runyon was dismantled, the garrison sent home, and the land returned to its owner, James Roach. Squatters — among them freed blacks — occupied the vacant fort, scavenging its timbers for building materials and firewood. Some years later, a brickworks located nearby used clay from the fort's embankments for raw material. And during World War II, the site was a staging area for the construction of the Pentagon.
". . . forts built in the early days of the conflict . . . were still standing in the suburbs. Plundered of their lumber by nearby farmers, they now served as shelter for the many freedmen . . . from the nearby plantations of Maryland and Virginia, from the wrecks of battery wagons and sentry boxes, they had improvised the flimsiest constructions."
James Huntington Whyte, from The Uncivil War: Washington During the Reconstruction 1865-1878
Grand Review at Washington — Sherman's Veterans Crossing Long Bridge, May 1865, from Harper's Weekly, June 10, 1865. Soldiers passed through Fort Runyon and crossed the Long Bridge one final time for the Grand Review and home.