The last conflict (1754–63) of theFrench and Indian Wars was ending disastrously for the French, and in order to keep the entire Louisiana territory from falling into the hands of the British, the French secretly ceded (by the Treaty of Fontainebleau in 1762) the area W of the Mississippi and the “Isle of Orleans” to Spain. By the Treaty of Paris, Great Britain gained control of all Louisiana E of the Mississippi except the “Isle of Orleans”; these changes were announced in 1764.
The French colonists resisted the new Spanish rule, but were subdued and finally Spanish mercantilistic monopoly of trade was instituted. During the Spanish years agriculture flourished with the cultivation of rice and sugarcane, and New Orleans grew as a major port and trading center. The Spanish government welcomed thousands of Acadians, known there as Cajuns, and they settled what came to be known as the Cajun country. During the American Revolution, New Orleans was a center for Spanish aid to the colonies. After Spain declared war on Great Britain in 1779, Louisiana’s governor, Bernardo de Gálvez, became an active ally of the revolutionists, capturing Baton Rouge and Natchez (1779), Mobile (1780), and Pensacola (1781).
After the war Louisiana’s control of the great inland trade route, the Mississippi, led to heated controversy with the Americans. In the secret Treaty of San Ildefonso (1800), Napoleon I forced the retrocession of the territory to France. Revelation of this treaty caused profound concern in the United States. President Jefferson attempted to purchase the “Isle of Orleans” from France. To the surprise of the American representatives in France, Napoleon decided to sell all of Louisiana to the United States.