Fort O'Rourke Fair Haven. No visible remains of the fort can be found. Fort O'Rourke Fort O'Rourke is a former Union Army installation now located in the Belle Haven area of Fairfax County in the U.S. state of Virginia. It was the southernmost fort built to defend Washington, D.C. in the American Civil War. Following the surrender of Fort Sumter in Charleston, South Carolina, on April 14, 1861, President Abraham Lincoln declared that "an insurrection existed," and called for 75,000 troops to be called up to quash the rebellion. The move sparked resentment in many other southern states, which promptly moved to
Fort Washita west to protect the new frontier. The Army established Fort Cobb in October 1859. Many men who served at Fort Washita would go on to become famous, including Randolph B. Marcy, George McClellan, William G. Belknap and Theophilus H. Holmes. Federal troops still occupied Fort Washita when the Confederates fired on Fort Sumter on April 12, 1861. Expecting war Colonel William Emory had concentrated all of his Federal troops from Forts Arbuckle and Cobb at Fort Washita. When news of Fort Sumter reached Emory on April 16 he led his forces to Fort Leavenworth, Kansas, pursued by 4000 Texas militia