The Demilune
Surrounded on all sides by the moat, the demilune (literally “half-moon”) protected the vulnerable fort entrance. This triangular area was modified in 1872 by the addition of earthen mounds which housed powder magazines. During the Civil War, the demilune was flat and included gun platforms , kitchens, mess rooms, storage areas and a guard house.
Plaque courtesy Lat34North.com.
Original page, with additional info, here.
Photo credit: Byron Hooks of Lat34North.com.