The North American Southeast remained a wild borderland where Indian tribes, the United States, Spain, and Great Britain competed fiercely for supremacy. After the War of 1812 Spain kept a tenuous hold on Florida; however, Spanish authorities could not enforce peace on the border and were unable to prevent black slaves from fleeing to Florida and joining the Seminole Indians. Seen from Washington the peninsula was a natural appendage to the United States, and James Monroe’s administration hankered to possess it.
Mahon, John K.
"The First Seminole War, November 21, 1817-May 24, 1818,"
Florida Historical Quarterly: Vol. 77:
1, Article 5.
Available at: https://stars.library.ucf.edu/fhq/vol77/iss1/5