An old French fort at Lake of the Two Mountains is named in Bougainville's List 1757. The Sulpicians obtained the seigniory of Montreal island in 1663 and established a mission at the fort, 12 leagues from Montreal. About 250 Indians, Nipissings, Algonquins, and Iroquois, traded at the post. The commerce was for the benefit of the priests and there was no French commander nor garrison at the fort in 1757. The site is now Oka on the north side of the river. The fort was probably built about 1660.

The Hudson's Bay Co. established a post on the Lake of Two Mountains in the spring of 1819 and the North West Co. also operated a post until the date of coalition 1821.