To prevent that threat from coming to pass, Brig. Gen. John G. Barnard, chief engineer of the defenses of Washington, directed that a line of forts be constructed on the heights southeast of the Anacostia River. From Fort Greble at the western end to Fort Mahan at the eastern end, the forts along the Eastern Branch River (as the Anacostia was then known) were not intended to constitute a continuous defensive line as was the Arlington Line that defended the Virginia approaches to the city. Instead, they were merely intended to deny Confederate artillery the position and to provide warning of any sneak attack upon Washington from the southeast. General Barnard illustrated this in an October 1862 report, saying, "As the enemy cannot enter the city from this direction, the object of the works is to prevent him seizing these heights, and occupying them long enough to shell the navy-yard and arsenal. For this, the works must be made secure against assault, and auxiliary to this object is the construction of roads by which succor can be readily thrown to any point menaced."