On December 27, 1860, one week after South Carolina seceded from the Union, the fort was surrendered to South Carolina (S.C.) militia by its small U.S. Army garrison, which retired to Fort Sumter to join Major Robert Anderson.
The Castle quickly proved to be too small and inadequate, however, for permanent confinement; the prisoners were transferred back to the Charleston City Jail on October 31, 1861, after only six weeks.