The French presence at the Straits began not with soldiers but with a priest. Father Jacques Marquette established the Mission of Saint Ignace in 1671, and within a decade the settlement had grown into a considerable community: the mission itself, a French village of a dozen cabins, a Wyandot village enclosed by a wooden palisade, and an adjacent Odawa village similarly fortified. Tensions ran high. In 1681, the Huron and Illiniwek at St. Ignace killed the Seneca chief Annanhac, who had been leading raids against western peoples. The Seneca were part of the Iroquois Confederacy, and the killing drew New France deeper into the Beaver Wars -- the sprawling conflict over who would control the continental fur trade. In 1683, Governor La Barre ordered Daniel Greysolon, Sieur du Lhut, and Olivier Morel de La Durantaye to fortify the mission. La Durantaye became overall commander of French forts in the northwest, responsible for outposts as far-flung as Fort Kaministigoya on Thunder Bay and Fort Saint Louis in present-day Illinois.

The fort that gave St. Ignace its military character was built in 1690 by commandant Louis de La Porte de Louvigne, constructed as a wooden stockade overlooking the Straits. During the 1690s it served as a staging ground for French and allied Indigenous raids against the Seneca, who had allied with the English. In 1694, Governor Frontenac -- for whom the fort was named -- sent his aggressive young protege Antoine de la Mothe Cadillac to run the post. Cadillac made a fortune, possibly through bribes. The Jesuit missionaries, led by Father Etienne de Carheil, accused him of encouraging the brandy trade with Native Americans. Cadillac may have seen alcohol sales as a necessary tactic to compete with English traders offering their own goods. La Durantaye, his honest predecessor, had controlled the brandy trade and policed the fur merchants with a firm hand. He died in poverty. Cadillac did not share his scruples.

While Cadillac enriched himself, the Huron chief Kondiaronk was shaping history. In 1697, Kondiaronk led an attack on the Seneca at Lake Erie and won a crushing victory. Four years later, he played a leading role in forging the Great Peace of Montreal in 1701, which ended decades of warfare between New France and the Iroquois Confederacy. That same year, Cadillac received permission from Paris to establish a new post on the Detroit River to block British trade goods from reaching Lake Huron. He took the Fort de Buade garrison south and founded Fort Pontchartrain du Detroit -- the seed of modern Detroit. The Huron followed Cadillac south; the Ottawa eventually relocated to the new Fort Michilimackinac built on the Straits' south shore in 1715. St. Ignace was largely abandoned.

After the garrison departed in 1701, Fort de Buade's fate becomes murky. Unlicensed coureurs de bois continued trading at Michilimackinac, and Governor Vaudreuil used them to smuggle goods to northern nations during the War of the Spanish Succession. The fort may have served as a storehouse until Fort Michilimackinac was completed on the south shore in 1715. After that, few French remained at East Moran Bay. The wooden stockade either was deliberately destroyed or simply rotted away. Archaeological searches have not located its remains. The fort that helped launch Detroit, shaped the Beaver Wars, and commanded one of North America's most strategic waterways has returned entirely to the earth -- somewhere beneath the streets and lawns of modern St. Ignace.