Fort Marcy Park
|Part of the Civil War defenses of Washington, D.C.|
|Fairfax County, Virginia|
|Fort Marcy as it appeared during the Civil War|
|Controlled by||Union Army|
|Built by||U.S. Army Corps of Engineers|
|Battles/wars||American Civil War|
At the end of the Civil War in 1865, the system of fortification (now known as Fort Circle Parks) which surrounded Washington, D.C. were dismantled. The lumber and other materials were sold at auctions and the land returned to pre-war owners. Fort Marcy is approximately 1/2 mile south of the Potomac River on the south side of the Chain Bridge Road leading from Chain Bridge to Langley and McLean, Virginia. The perimeter of the fort is 338 feet (103 m). When completed, the fort mounted 18 guns, a 10-inch (25 cm) mortar and two 24-pound (10 kg) Coehorn mortars. The batteries were aimed toward the south and west.
The hill on which the fort is located was known as Prospect Hill. Originally the fort was called Fort Baldy Smith, after General William Farrar Smith, the troops of whose division began construction of the work. His division crossed Chain Bridge on the night of September 24, 1861, and immediately commenced construction of Fort Marcy and Fort Ethan Allen.  The 79th New York Highlanders, the 141st Pennsylvania and the Iron Brigade also helped complete the work in the fall of 1862. A force of about 500 contrabands were also employed and the 152nd New York worked on the entrenchments, which incidentally are still in a very good state of preservation. The site of Fort Marcy is near the location where the famous but bloodless duel between Henry Clay and John Randolph was fought in 1826.
The fort was not completed until the fall of 1862. It is a relatively undisturbed fort and was named in honor of a native of Massachusetts, Randolph B. Marcy, a distinguished soldier and father-in-law and chief of staff to General George B. McClellan.  Detachments of the 4th New York and 3rd Pennsylvania Heavy Artillery and the 130th Pennsylvania infantry were among the troops that performed garrison duty here during the war. An interesting incident of history is that the body of troops which afterwards became famous as the "Iron Brigade" was originated at this fort in the summer of 1861, and was composed of the 19th Indiana, the 2nd, 6th and 7th Wisconsin Regiments. The 24th Michigan was added to the brigade soon after the Battle of South Mountain. These units remained together until the close of the war.
- Cooling III, Benjamin Franklin; Owen II, Walton H. (6 October 2009). Mr. Lincoln's Forts: A Guide to the Civil War Defenses of Washington. Scarecrow Press. pp. 123–128. ISBN 978-0-8108-6307-1.