Amherst Island was originally inhabited by Indigenous peoples who gave it the name Kaounesgo. Amherst Island was known by the French as Isle Tonti, after Henri de Tonty, who accompanied La Salle during his explorations. The island was later settled by United Empire Loyalists. In a proclamation by the Lieutenant Governor of Upper Canada John Graves Simcoe on 16 July 1792, the island was renamed from Isle Tonti to Amherst Island, in honour of Jeffery Amherst, 1st Baron Amherst, who was commander-in-chief of British forces in North America. At the same time, he named the archipelago for the victorious Generals at the Battle of the Plains of Abraham: Wolfe Island, this one, Howe Island, Carleton Island and Gage Island. The last is now known as Simcoe Island.