Chimney Island (Bridge Island)
During the War of 1812 the St. Lawrence was the life-line of Upper Canada along which virtually all military and civilian supplies were transported from Montreal to Kingston. Fear that the Americans might attempt to block the passage of material prompted the fortification of Bridge Island as a shelter for the supply batteaux and a base for British gunboats. A blockhouse was completed early in 1814 and a circular battery with an 18-pounder constructed. These defence works were maintained by a detachment of the 57th Regiment and artillerymen during 1814, but fell into disrepair soon after the war.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.