Just across the Potomac River from the Union capital city, ConfederateVirginia was a major Union concern when the war began. In May 1861, federal troops seized much the County and immediately began constructing a group of forts near Washington on the Virginia side of the River to protect the capital city.
The Arlington Line was never attacked, even after the federal defeat at the Second Battle of Bull Run (Manassas) in late August 1862. The Line therefore effectively served its strategic purpose.
^(1) Michael, John (2011-03-06). "Fort Cass Virginia: The Fortification Begins". Images of America: Fort Myer. Archived from the original on 2018-12-28. Retrieved 2018-12-28. After the fall of Fort Sumter, South Carolina to the Confederates, it was decided that the Nation's Capital was in need of defenses. Among the first fortifications were built were the ones at the three crossings of the Potomac River – Chain Bridge (Fort Ethan Allen), Aqueduct Bridge (Fort Corcoran) and Long Bridge (Fort Jackson). Over time the Arlington Line of fortifications developed beginning at the Potomac and encircling the western side of the Capital on the Virginia side. The line consisted of about 30 forts, augmented by interwoven artillery batteries: Fort Marcy, Fort Ethan Allen, Fort C. F. Smith, Fort Bennett, Fort Strong, Fort Corcoran, Fort Haggerty, Fort Morton, Fort Woodbury, Fort Ramsey (which later renamed and became Fort Cass), Fort Whipple, Fort Tillinghast, Fort McPherson, Fort Buffalo, Fort Craig, Fort Albany, Fort Jackson, Fort Runyon, Fort Richardson, Fort Barnard, Fort Berry, Fort Scott, Battery Garesche, Fort Reynolds, Fort Ward, Fort Worth, Fort Williams, Fort Ellsworth, Fort Lyon, Fort Farnsworth, Fort Weed, Fort O'Rourke, Fort Willard (2) "The Arlington Line". Arlington County, Virginia: Arlington Historical Society. Archived from the original on 2012-04-20. (3) Cooling III, Benjamin Franklin; Owen II, Walton H. (2010). "The Arlington Lines". Mr. Lincoln's Forts: A Guide to the Civil War Defenses of Washington (New ed.). Lanham, Maryland: Scarecrow Press. p. 82. ISBN978-0-8108-6307-1. LCCN2009018392. OCLC665840182. Archived from the original on 2018-12-28. Retrieved 2018-03-05 – via Google Books.