Fort McAllister stands on Genesis Point on the south bank of the Great Ogeechee River, in Bryan County about half an hour south of Savannah. The Confederates built it as an earthwork fort to guard the river approach to Savannah. Its sand-and-mud walls, ten heavy guns and a hot-shot furnace for heating cannonballs red-hot let it absorb punishment that would have shattered brick. Union ironclads attacked it seven times in 1862 and 1863, and the fort did not fall.

On February 1, 1863, during the second attack by the monitor USS Montauk, the fort's commander, Major John B. Gallie, was killed when a shell struck the 32-pounder beside him as he went from gun to gun encouraging his men. The fort finally fell on December 13, 1864, when Sherman's army arrived by land at the end of the March to the Sea. Sherman watched from across the river as some 4,000 Union troops overran about 120 defenders under Major George W. Anderson in roughly fifteen minutes of fierce, often hand-to-hand fighting. Its capture opened the river to Union supply ships, and Savannah surrendered soon after. The fort then served for a time as a prison for captured Confederates.

In the 1930s Henry Ford, who owned the surrounding plantation land, had the earthworks repaired and rebuilt. Today it is Fort McAllister State Park, described by Georgia State Parks as the best-preserved earthwork fortification of the Confederacy. It was listed on the National Register in 1970. The park is open to the public by day, and admission covers the fort and a Civil War museum. The fort is closed at night.