French nobleman Robert Cavalier de La Salle had launched an expedition down the Mississippi River from New France in 1681, at first believing he would find a path to the Pacific Ocean.
Instead, La Salle had found a route to the Gulf of Mexico.
Although Hernando De Soto had explored and claimed this area for Spain one hundred and forty years before, on April 9, 1682, La Salle had claimed the Mississippi River valley for French king Louis XIV, naming the territory Louisiana in his honor.
Without a French presence at the base of the Mississippi, Spain would have an opportunity to control the entire Gulf of Mexico and potentially pose a threat to New France's southern borders.
La Salle believes that the Mississippi River is near the eastern edge of New Spain, and on his return to France in 1683, he had proposed establishing a colony at the mouth of the river.
The colony could provide a base for promoting Christianity among the native peoples as well as a convenient location for attacking the Spanish province of Nueva Vizcaya and gaining control of its lucrative silver mines.
He had argued that a small number of Frenchmen could successfully invade New Spain by allying themselves with over fifteen thousand Native Americans who are angry over Spanish enslavement.
After Spain declared war on France in October 1683, Louis had agreed to support La Salle's plan; his official duties now include "confirming the Indians' allegiance to the crown, leading them to the true faith, and maintaining intertribal peace".
La Salle had originally planned to sail to New France, journey overland to the Illinois Country, and then traverse the Mississippi River to its mouth.
However, to spite Spain, Louis has insisted La Salle sail through the Gulf of Mexico, which Spain considers its exclusive property.
Although La Salle had requested only one ship, on July 24, 1684, he leaves La Rochelle, France with four: the thirty-six-gun man of war Le Joly, the three hundred-ton storeship L'Aimable, the barque La Belle, and the ketch St. François.
Although Louis XIV had provided both Le Joly and La Belle, La Salle had desired more cargo space and leased L'Aimable and St. François from French merchants.
Louis has also provided on hundred soldiers and full crews for the ships, as well as funds to hire skilled workers to join the expedition.
La Salle himself is forced to purchase goods to trade with the Native Americans.