In 1749, the Sulpician missionary, Abbé Francois Picquet, built a fort where the Oswegatchie River empties into the St. Lawrence River (present-day Ogdensburg, New York). He invited the Iroquois to come to Fort de La Présentation to learn about Catholicism. To settle at La Présentation, families had to agree to live monogamously, convert to Catholicism, give up alcohol and swear allegiance to France. By 1751, 396 Haudenosaunee families, largely Onondaga with some Oneida and Cayuga, had settled in the area between Toniato Creek (now known as Jones Creek, in Thousand Islands National Park) and the Long Sault. They came to be called the Oswegatchie. This was one of the Seven Nations of Canada.
While never allowed as a separate tribal member of the Iroquois Confederation, the Oswegatchie were considered "nephews" because of their members' family ties to the Six Nations. When the Seven Years' War broke out between France and England, the Oswegatchie fought with the French on numerous raids in the Ohio, Champlain and Mohawk valleys, where they attacked British colonists.