Fort Mackinac

Fort Mackinac is an American former military outpost garrisoned from the late 18th century to the late 19th century near Michilimackinac, Michigan, on Mackinac Island. The British built the fort during the American Revolutionary War to control the strategic Straits of Mackinac between Lake Michigan and Lake Huron (and by extension the fur trade on the Great Lakes) and did not relinquish it until fifteen years after American independence.

• http://en.wikipedia.org/wiki/Fort Mackinac