Fort Sumter is a sea fort in Charleston, South Carolina, notable for two battles of the American Civil War. It was one of a number of special forts planned after the War of 1812, combining high walls and heavy masonry, and classified as Third System, as a grade of structural integrity. Work started in 1829, but was incomplete by 1860, when South Carolina seceded from the Union. The First Battle of Fort Sumter opened on April 12, 1861, when Confederate artillery fired on the Union garrison.