 Much of the work at the fort dealt with maintenance and renovation of the original structure, which had been hurriedly thrown up in the wake of the Union advance into Arlington after the secession of Virginia.An 1864 report by Brigadier General Richard Delafield, chief of the U.S. Army Corps of Engineers lists an extensive series of improvements made to the fort over the previous year.This work was typically done by the soldiers of the garrison, who supplied much of the labor for all of the defenses protecting Washington.