The First Seminole War begins in 1817 with General Andrew Jackson's excursions into West Florida and Spanish Florida against the Seminoles after the conclusion of the War of 1812.

The governments of Great Britain and Spain both express outrage over the "invasion".

However, Spain is unable to defend or control the territory, as several local uprisings and rebellions make clear.

The Spanish Crown agrees to cede Florida to the United States per the Adams–Onís Treaty of 1819, and the transfer takes place in 1821.

According to the Treaty of Moultrie Creek of 1823, the Seminoles are required to leave northern Florida and are confined to a large reservation in the center of the Florida peninsula.

The U.S. government enforces the treaty by building a series of forts and trading posts in the territory, mainly along the Gulf and Atlantic coasts.