The expedition had been in the making for eight years. Daniel de la Touche, Seigneur de la Ravardière, had first reached the region in 1604, but the assassination of King Henry IV of France in 1610 had delayed the colonial push. His co-commander, Admiral François de Razilly, was one of three Razilly brothers who pursued French naval interests in the Americas for decades. Together they left the Brittany port of Cancale in early 1612, carrying soldiers, artisans, farmers, and the Capuchin friar Claude d'Abbeville, who would write the expedition's official account. They arrived at Upaon-Açu in August, negotiated with the local Tupinambá leaders - who by this point had decades of European contact and maintained a complex political relationship with Portuguese, French, and Dutch traders - and chose a rise of ground on the island's western side for their settlement. They named it Saint-Louis, in honor of the canonized French king Louis IX. Capuchin friars prayed the first mass on September 8. The soldiers began building the fortress that would give the settlement its early shape.

The French did not arrive to uninhabited land. The Tupinambá had lived on Upaon-Açu and the surrounding coast for generations. They had absorbed multiple waves of European contact before 1612 - French traders on the pau-brasil dyewood coast, Portuguese raids, Dutch visits, Jesuit missions. Their chief Japiaçu crossed the Atlantic with the Capuchins on a diplomatic mission to Louis XIII in Paris in 1613, a journey recorded in Claude d'Abbeville's Histoire de la Mission. A second Tupinambá leader, Louis Henri, made the same trip. To the French colonists, these were useful political partners. To the Tupinambá themselves, they were people with their own motives for tolerating or resisting the newcomers, calculated against the already-present Portuguese pressure from the south. What no one in 1613 understood clearly was how completely the next decade would shatter the Tupinambá political world - and how many of them would not survive it.

From the Captaincy of Pernambuco, Portuguese commander Alexandre de Moura mobilized a counter-expedition. France and Portugal had been at nominal peace, but Portuguese claims to Brazil rested on the 1493 papal bull Inter caetera and the Treaty of Tordesillas, which divided the New World between Spain and Portugal. French settlements on the Brazilian coast violated both treaties. De Moura assembled a force, sailed north, and in November 1615 fought the Battle of Guaxenduba and laid siege to Saint-Louis. By that point the French colony had been debilitated by disease, uneven supply lines, and a dependence on Tupinambá allies who had their own problems. La Ravardière negotiated a surrender. The French marched out. Portuguese forces renamed the settlement São Luís - preserving the French name in translation, which is why the city's name still honors a French king. The Portuguese consolidation that followed, beginning with a wave of colonists in 1620, brought sugar cane plantations, imported enslaved Africans, and the displacement and killing of the Tupinambá communities that had survived the French period.

Equinoctial France did not give up on the equator. French traders tried again in 1626 and 1635, founding Cayenne in what is now French Guiana. A Compagnie de la France Équinoxiale was chartered twice, in 1643 and 1645, and failed both times under mismanagement and disease. Only after 1674, when the French crown took direct control and installed a competent governor, did the territory stabilize. It is the reason French Guiana exists today as a department of France - a slice of South America that uses the euro, flies the French flag, and launches rockets for the European Space Agency from Kourou. São Luís, meanwhile, kept its French-flavored name but became a Portuguese-speaking, Luso-African city whose historic center is a UNESCO World Heritage Site. Walking the tiled streets there, you see the colonial architecture of a city that was French for three years and Portuguese for four hundred - and that sits on land that was Tupinambá long before either.