Fort Ellsworth, one of 68 earthen forts built to protect Washington during the Civil War, was constructed in 1861. When completed, the fort had a perimeter of 618 yards and was an irregular Vauban-type star design of French origin. The fort was garrisoned by many regiments in the course of the war. The largest of its guns, a 100-pound Parrott, had a maximum range of 8,428 yards. The fort was named for Colonel Elmer E. Ellsworth, Commander of the 11th New York Fire Zouaves and a friend of President Lincoln. Colonel Ellsworth was the first Union officer to be killed in the Civil War. He was shot at Marshall House, Alexandria, after removing a Confederate flag from the tavern roof, and lay in state at the White House. He is buried in Mechanicville, New York.