Fortifications

Fort Whipple (1863-1865) - A Union U.S. Civil War Fort first established in 1863 in present day Arlington County, Virginia. Named Fort Whipple after Major General Amiel W. Whipple, who died 7 May 1865 of wounds received at Chancellorsville. The fort was abandoned in 1865 at the end of the war but was later reestablished and became Fort Myer.

(Source - Fortwiki)