Fort Myer encompasses the former sites of Forts Whipple and Cass, built as part of defenses of Washington during the Civil War to guard the approaches to the Aqueduct Bridge (near the site of the present day Key Bridge).   Fort Whipple was a bastion fort built in 1863 following the Union Army's defeat at the Second Battle of Bull Run (Manassas) and was named after Brevet Major General Amiel Weeks Whipple, who died in May 1863 of wounds received during the Battle of Chancellorsville.  Fort Cass, a lunette, was named after Colonel Thomas Cass, of the 9th Massachusetts Infantry, who was responsible for its construction in 1861. 

Fort Myer was named in 1881 in honor to Brigadier General Albert J. Myer, who commanded the newly established Signal School of Instruction for Army and Navy Officers and who originated the National Weather Service there. 

Since that time, Fort Myer has served as a Signal Corps post, a showcase for the U.S. Army's cavalry, and the home to the Army's elite ceremonial units — The U.S. Army Band ("Pershing's Own") and the 3rd U.S. Infantry Regiment ("The Old Guard"). 

For more information, see Mr. Lincoln's Forts: A Guide to the Civil War Defenses of Washington, by Benjamin Franklin Cooling III and Walton H. Owen II. 

Source: Map by Engineer Bureau, U.S. War Department, Via Library of Congress, Geography and Map Division (1865)

Patton Hall, Officers' Club, Fort Myer, Arlington VA