Fort St. Joseph
The most westerly military post in Upper Canada. Built in 1796-99, and garrisoned from 1796 to 1812 by parties from the Queen's Rangers, Royal Canadian Volunteers, 41st and 49th Regiments and 10th Royal Veteran Battalion. It became a noted trading station and resort for Indians. A court of requests was established in 1808. Here Captain Charles Roberts organized the expedition that took Mackinac, 17th July, 1812.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.