Charles Lennox 4th Duke of Richmond and Lennox (1764-1819)
Charles Lennox was appointed Commander-in-Chief of all the British North American colonies and Governor-in-Chief of Lower Canada in May 1818. He received a mandate to improve the colonies' defences and inland navigation system. Lennox recommended the strengthening of the fortifications at Québec City and the building of a fort, later named in his honour, on Île aux Noix and also promoted canal construction on the Ottawa River. His sudden death near here only a year after his appointment was lamented in both Canada and Britain.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.