Fort Richardson was a detached redoubt that the Union Army constructed in September 1861 as part of the Civil War defenses of Washington (see Washington, D.C., in the American Civil War). The Army built the fort shortly after its rout at the First Battle of Bull Run (Manassas) in late July 1861. The Army named the fort after General Israel B. Richardson, whose division had been deployed to defend the City of Washington against attack by way of the Columbia Turnpike.