Driving the George Washington Parkway north along the Potomac, you can almost miss the entrance to Fort Marcy Park. It’s not a well-known Civil War fortification, not being a sight of one of that war’s destructive battles, but it was one of the key components of the Union’s defense of the capital. (It’s also known as the place where White House Counsel Vince Foster’s body was discovered in 1993, but that’s not really relevant today.)

At the beginning of the Civil War, there was only one operational fort (Fort Washington, over in Maryland) to defend against Confederate encroachment. A huge effort was made to establish a defensive ring of forts around the capital, eventually resulting in a ring of eight enclosed forts and over 90 gun batteries by 1865. These preparations made DC one of the most heavily fortified cities in the world at that time.

Fort Marcy, located on a ridge called Prospect Hill in northern Virginia, was placed to provide strategic defense of the Chain Bridge, a key crossing over the Potomac (and one of the key bridges in today’s transportation network). The Chain Bridge was a vital part of maintaining Union army activity in north Virginia. The land belonged to local businessman Gilbert Vanderwerken, who suffered from the predation of the Confederates at his plantation in Falls Grove. The Union army moved onto his land and prepared both Fort Marcy and Fort Ethan Allen, clearing trees and building the much-needed batteries.

The fort consisted of a perimeter of over 700 yards and contained 18 gun emplacements. The ramparts were between 12 and 18 feet thick; with the trees cleared from the area, the soldiers at the fort had extremely good visibility towards both Chain Bridge and Leesburg Pike.

In 1862, the fort was renovated due to weather erosion. The perimeter was reduced to just under 340 yards but maintained its compliment of 18 guns.

Fort Marcy got its name from the Honorable Randolph B. Marcy, General McClellan’s father-in-law and chief of state. The fort was manned by detachments of the 4th New York and 3rd Pennsylvania Heavy Artillery, with infantrymen from the 130th Pennsylvania providing garrison duty.

While the fort never actually saw action during the war, it was often in a high alert status, due to its proximity to the Chain Bridge and its strategic position on the river. However, Lee never made a move on DC – knowing full well the respectable barrier the Circle Fortifications made – but was instead intent on driving Union troops from Virginia. As such, Fort Marcy remained only a strong sentinel against Confederate aggression.

After the war, the Fort was dismantled and the land returned to the Vanderwerken family. After World War II, the DeLashmutt family purchased the land where the fort had been and in 1959, Fort Marcy was deeded to the federal government. The park was opened to the public in 1963.

Fort Marcy still maintains a solid presence today. While much of the earthworks have eroded, you can still see the sloping and shape of the main fortifications, though the walls are nowhere as high as they were during the war. Some cannon were moved back to the area and positioned to give you an idea of possible locations and a marked trail circles the entire fort along the lines of the original entrenchment. The trail is quiet, though does have several steep descent / ascent spots; plan on taking your time to go the full circuit.

While it’s a bit hard to imagine what the sightlines were during its active period due to the proliferation of trees, it’s not difficult to recognize its value once you see it on a map. If Lee had decided to push towards Washington from Virginia, the Chain Bridge approach would probably have been a top choice for his attack and Fort Marcy may well have been more than a peaceful, silent monument to that era along the Potomac.

All photos courtesy of me.