Confederate soldiers and slaves built this 15-acre earthen fort over a period of seven months, using axes and shovels to make a wall of logs and earth ten feet high. Although a fort constructed of brick or stone may have provided more permanence, earthen walls could be built more quickly. Properly constructed earthworks provide better protection than brick or stone. The Confederates built the fort to protect the Cumberland River batteries from land attack. At the time of the battle, all the trees around the fort for over two hundred yards were felled, to provide clear fields of fire and observation. Sharpened tree branches were pointed toward the enemy, forming an obstacle called an abatis.