Castle Pinckney is a small masonry fortification constructed by the United States government, in the harbor of Charleston, South Carolina, in 1810.

A replacement brick-and-mortar structure called "Castle Pinckney" was erected in 1809–1810 and was garrisoned throughout the War of 1812, but it saw no action during the two-and-a-half-year conflict.

[4] 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.

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 Forts Sumter and Moultrie, and other, smaller earthworks and fortifications.

In 1860, Castle Pinckney's armament consisted of fourteen 24-pounders, four 42-pounders, four 8-inch howitzers, one 10-inch and one 8-inch mortar, and four light field pieces to protect its flanks.

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.

In 1951, Congress passed a bill to abolish Castle Pinckney National Monument and transferred it back to U.S. Army Corps of Engineers.

[11] A local Sons of Confederate Veterans fraternal post took over management and care of the island in the late 1960s, attempting to preserve it and establish a museum.