United States territorial acquisitions
West Florida was declared to be a U.S. possession in 1810 by President James Madison after the territory had declared its independence from Spain. Madison ordered the U.S. Army to take control. Six weeks later, the army entered and occupied the capital, St. Francisville, putting an end to the republic after 74 days of independence. Spain did not relinquish its claim to sovereignty (see West Florida Controversy) until ratification of the Adams–Onís Treaty. General Andrew Jackson personally accepted the delivery of West Florida from its Spanish governor on July 17, 1821.
Castillo de San Marcos
When Britain gained control of Florida in 1763 pursuant to the Treaty of Paris, St. Augustine became the capital of British East Florida, and the fort was renamed Fort St. Mark until the Peace of Paris (1783) when Florida was transferred back to Spain and the fort's original name restored. In 1819, Spain signed the Adams–Onís Treaty which ceded Florida to the United States in 1821; consequently the fort was designated a United States Army base and renamed Fort Marion, in honor of American Revolutionary War hero Francis Marion. The fort was declared a National Monument in 1924, and after 251 years of continuous military possession, was deactivated in 1933. The site was subsequently turned over to the United States National Park Service. In 1942 the original name, "Castillo de San Marcos", was restored by an Act of Congress.