Castle Pinckney Castle Pinckney was a small masonry fort ification constructed by the United States government by 1810 in the harbor of Charleston , South Carolina . It was used very briefly as a prisoner - of - war camp ( six weeks ) and artillery position during the American Civil War . It was named to the National Register of Historic Places in 1970 . History . Located on Shutes ' Folly , an island one mile offshore from Charleston , the Castle fort was built over the ruins of an older fortification called " Fort Pinckney " . The original log and earthen fort , named after the Revolutionary War hero Charles Cotesworth Pinckney , was built beginning in 1797 and was intended to protect the city from a possible naval attack when war with France seemed imminent . Completed in 1804 , it saw no hostilities and was virtually destroyed by a severe hurricane in September of that year . A replacement brick and mortar structure called " Castle Pinckney " was erected in 1809 – 1810 and was garrisoned throughout the War of 1812 , but saw no action . Afterwards , Castle Pinckney was abandoned and fell into disrepair . Two decades later , a sea wall was completed and the fort was re - garrisoned during the Nullification Crisis of 1832 , when President Andrew Jackson prepared to collect a controversial tariff using military force if necessary . After that brief period of activity , the fort again fell into disuse and was primarily a storehouse for gunpowder and other military supplies . By the late 1850s , Castle Pinckney was part of a network of defensive positions in the harbor , which included the larger and more strategically placed Fort Sumter and Fort Moultrie , and other smaller earthworks and fortifications . In 1860 , Castle Pinckney ' s armament consisted of fourteen 24 - pounders , four 42 - pounders , four 8 - inch howitzer s , one 10 - inch and one 8 - inch mortar and four light fieldpieces to protect its flanks . On December 27 , 1860 , one week after South Carolina seceded from the Union , the fort was surrendered to South Carolina militia by its small garrison , which retired to Fort Sumter to join Major Robert Anderson . Castle Pinckney became the first Federal military position seized forcefully by a Southern state government . Three days later , the Charleston Arsenal joined Castle Pinckney in falling to the militia . After the subsequent attack on Fort Sumter , the Charleston Zouave Cadets manned Castle Pinckney . One hundred and fifty - four Union Army prisoners of war ( 120 enlisted , 34 officers ) captured during the First Battle of Manassas and previously incarcerated at Ligon ' s Prison arrived at Charleston on September 10 , 1861 and were kept at the Charleston City Jail until the lower casements of Castle Pinckney were converted into cells . According to the " Charleston Mercury " , Richmond officials had selected " . . chiefly from among those who have evidenced the most insolent and insubordinate disposition " . On September 18 , prisoners from the 11th NY Fire Zouaves , 69th NY ( " Irish " ) Regiment , 79th NY Regiment , and 8th Michigan Infantry were transferred to Castle Pinckney . They were allowed to wander during the day and were confined to cells only at night . The Castle quickly proved to be too small and inadequate however for permanent confinement and the prisoners were transferred back to the Charleston City Jail on October 31 , 1861 after only six weeks . After the prisoners were removed , the fort was strengthened with earthen embankments and additional mortars and Columbiads on the barbette tier . On December 12 , the prisoners were transferred back to the island following a fire which had burned a large section of Charleston and damaged the jail . They remained for just over a week with many sleeping on the inner parade ground before being transferred . After the Civil War , the fort was modernized for possible use during the Spanish - American War but again was not needed . Some sources suggest that the fort never fired a single hostile shot during its lengthy existence . Parts of the old brick walls and casemates were dismantled in 1890 to make way for a harbor lighthouse , which operated into the 20th century . Castle Pinckney was declared a U . S . National Monument in 1924 by presidential proclamation . In 1951 , Congress passed a bill to abolish Castle Pinckney National Monument and transferred it back to U . S . Army Corps of Engineers . A local Sons of Confederate Veterans fraternal post took over management and care of the island in the late 1960s and attempted to preserve it and establish a museum . Castle Pinckney was listed on the National Register of Historic Places in 1970 . Eventually , unable to raise the needed funds , the SCV allowed the fort to revert to state ownership . Castle Pinckney has recently undergone some limited restoration efforts . Due its location on an isolated shoal in the middle of the harbor , access is limited , if not nonexistent , and maintenance near impossible . It is gradually being reclaimed by nature . In June , 2011 , Castle Pinckney was sold to the Fort Sumter Camp No . 1269 , Sons of Confederate Veterans for $ 10 .