Fort Pickens, within the National Seashore, is located on the western tip of Santa Rosa Island. The fort, named for Brigadier General Andrew Pickens of the South Carolina State Troops in the American Revolution, was built between 1829 and 1834. The Army Corps of Engineers used 21,500,000 bricks to build the original five-sided fort. During the Civil War, Fort Pickens remained in Union hands. Federal troops engaged in artillery duels with their Confederate counterparts who held Fort Barrancas. The fort was expanded during the Sapnish-American War but then fell into disuse.