Any claim that France may have had to all or any portion of St. Joseph Island ended with the conclusion of the Seven Years' War in 1763. Under the terms of treaty, France relinquished virtually all of its interests in North America to the British. For the first time, the British and their First Nations allies were unchallenged on the Great Lakes. Included in the French assets was the strategically important fort at the Straits of Mackinac between lakes Huron and Michigan west of St. Joseph Island. From Fort Mackinac, the British were able to control the flow of trade in and out of Lake Michigan.