B. Establish large settlements
France regained sovereignty of the western territory in the secret Third Treaty of San Ildefonso of 1800. But strained by obligations in Europe, Napoleon Bonaparte sold the territory to the United States in the Louisiana Purchase of 1803, ending France's presence in Louisiana.
1800 – In the Third Treaty of San Ildefonso, Napoleon secretly acquired the territory, but Spain continued to administer it. 1801 – The United States was permitted again to use the port of New Orleans. 1803 – The purchase of Louisiana by the United States was announced.