Cockspur Island, island, Chatham county, southeastern Georgia, U.S., in the mouth of the Savannah River. Known during colonial times as Peeper Island, it was given the name Cockspur for the shape of its reef. Its strategic advantages were early recognized; in the 18th century the island held Fort George (dismantled 1776), used mainly for defense against privateers, and, later, Fort Greene (destroyed by hurricane 1804), which was used for quarantine and customs and for inspecting slave-trading ships.
When the War of 1812 once again made clear the need for coastal defense, Fort Pulaski (named for the U.S. colonial army officer Kazimierz Pulaski) was built (1829–47). Following its completion, the fort remained ungarrisoned until it was seized by Confederate troops in January 1861, just before the outbreak of the American Civil War. It was bombarded and captured by Union troops in 1862, which cut off traffic to the port at Savannah. The Union bombardment marked the first time rifled artillery had been used, and the ease with which the fort’s walls were breached signaled the end of masonry fort construction.
Fort Pulaski National Monument was established in 1924. Occupying about 9 square miles (23 square km) of Cockspur and neighbouring McQueens islands, the monument preserves the restored fort and surrounding wildlife habitats.