 First, the Spanish founded St. Augustine, Florida in 1565 to protect their shipping lanes for treasure-laden ships sailing up from South America.As the French sought newer fur trade markets in the South, and ultimately the Southeast, French Louisiana was expanded in the late 17th century down the Mississippi and into the Gulf region.To curb French encroachment from the west, and to undermine Spain's traditional claims to areas north of Florida, the British colonists deemed it vital to expand and defend their southern borders, especially at the Savannah River.