1815: The Americans Return to Mackinac Island Posted June 23, 2017 On July 18, 1815, Mackinac Island once again became part of the United States after three years of British occupation during the War of 1812. The war brought many changes to the island, including the construction of a second fort on the heights of Mackinac. This weekend, this small post, Fort Holmes, will come to life to tell the story of Mackinac Island during the early years of peace. Â (more…)