Fort Fisher was an engineering marvel during the American Civil War and the largest earthen fortification ever built by the Confederacy. Unlike earlier masonry forts such as Forts Macon and Sumter, it was built of earth, stretched more than one and a half miles, and was shaped like the number "7." Construction continued throughout the war under the direction of Col. William Lamb. For two and a half years, about 1000 men worked on it each day, including impressed enslaved laborers and soldiers stationed at the fort. Contemporary observers praised the works as unmatched in the Confederacy and built to withstand prolonged bombardment, and they credited General Whiting's engineering skill throughout. In 1863, Sgt. T.A. McNeill wrote that the builders were raising a mountain seventy two feet high and described sand forts constructed with wheelbarrows moving in unison along gangways as loaders shoveled sand into them without stopping.