Chatham Blockhouse 1794
On this site a blockhouse was constructed in 1794 by order of Lieutenant-Governor John Graves Simcoe. He planned to establish here a small naval arsenal which would form a link in the defences of Upper Canada's western frontier and also draw the Indian trade from Detroit. The post was garrisoned by a detachment of the Queen's Rangers, and two gunboats were built; but by 1797 it was abandoned. In 1798 the province's Administrator, Peter Russell, had the blockhouse moved to Sandwich to serve as the Western District's court-house and gaol.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.