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.
History of Pensacola, Florida
After the transfer of the vast Louisiana Territory from Spain to France at the end of the 18th century, and the subsequent purchase of the region by the United States in 1803, Spanish East and West Florida were surrounded by American Southern states and territories. Anglo-American settlement of West Florida increased and the Spanish, busy with growing rebellions throughout Mexico and South America, were not able to focus on fortifying the region. In 1810, American settlers in the part of Florida west of the Pearl River (today the boundary between Louisiana and Mississippi) declared the West Florida Republic a state independent from Spain. The region was annexed into the new state of Louisiana in 1812.