USS Cairo is the lead ship of the City-class casemate ironclads built at the beginning of the American Civil War to serve as river gunboats. Cairo is named for Cairo, Illinois. In June 1862, she captured the Confederate garrison of Fort Pillow on the Mississippi River, enabling Union forces to occupy Memphis. As part of the Yazoo Pass Expedition, she was sunk on 12 December 1862, while clearing mines for the attack on Haines Bluff.