History of Florida
In 1810, parts of West Florida were annexed by proclamation of President James Madison, who claimed the region as part of the Louisiana Purchase. These parts were incorporated into the newly formed Territory of Orleans. The U.S. annexed the Mobile District of West Florida to the Mississippi Territory in 1812. Spain continued to dispute the area, though the United States gradually increased the area it occupied.Seminole Indians based in East Florida had been raiding Georgia settlements, and runaway American slaves were their allies; Negro Fort, an abandoned British fortification in the far west of the territory, was manned by both Indians and blacks. The United States Army would lead increasingly frequent incursions into Spanish territory, including the 1817–1818 campaign against the Seminole Indians by Andrew Jackson that became known later as the First Seminole War. The United States now effectively controlled East Florida. Control was necessary, according to Secretary of State John Quincy Adams, because Florida had become "a derelict open to the occupancy of every enemy, civilized or savage, of the United States, and serving no other earthly purpose than as a post of annoyance to them." Florida had become a burden to Spain, which could not afford to send settlers or garrisons. Madrid therefore decided to cede the territory to the United States through the Adams–Onís Treaty, which took effect in 1821.
Spanish Florida
After American independence, the lack of specified boundaries led to a border dispute with the newly formed United States, known as the West Florida Controversy. The two 1783 treaties that ended the American Revolutionary War had differences in boundaries. The Treaty of Paris between Britain and the United States specified the boundary between West Florida and the newly independent U.S. at 31°. However, in the companion Peace of Paris between Britain and Spain, West Florida was ceded to Spain without its boundaries being specified. The Spanish government assumed that the boundary was the same as in the 1763 agreement by which they had first given their territory in Florida to Britain, claiming that the northern boundary of West Florida was at the 32° 22′ boundary established by Britain in 1764 after the Seven Years' War. The British line at 32° 22′ was close to Spain's old claim of 32° 30′, which can be justified by referring to the principle of actual possession adopted by Spain and England in the 1670 Treaty of Madrid. The now independent United States insisted that the boundary was at 31°, as specified in its Treaty of Paris with Britain.