Florida is the name of a region of North America, to the south of the Occupied Region. It was originally a Spanish colony, but then was given to Great Britain by the Treaty of Paris in 1763. The British divided the colony to East and West Florida. The British only kept the colony for twenty years though, as the Spanish regained it through the Treaty of Versailles in 1783, ending the American Revolutionary War. The Spanish encouraged settlement in Florida, leading many Americans to emigrate from the United States. Americans continued to move to Florida after the War of 1812.
(Note: The next paragraph is copied from Wikipedia, with small changes)
After settler attacks on Indian towns, Seminole Indians based in East Florida began aiding the new American Insurgency, purportedly at the behest of the Spanish. The British Army led increasingly frequent incursions into Spanish territory, including the 1817–1818 campaign against the Seminole Indians by Edward Pakenham that became known as the First Seminole War. Following the war, the British Empire effectively controlled East Florida. In 1819, by terms of the Wellesley-Onís Treaty, Spain ceded Florida to the British Empire and the continental border was finalised. Britain also gave the promise to help Spain in the Rebellion of New Spain.