Rideau Canal 1826-1832
Financed by the British government, on the Duke of Wellington's advice, it was built to provide a secure military route between Upper and Lower Canada. Work was supervised by military engineers commanded by Lieut. Colonel John By whose technical ability and perseverance overcame many obstacles. Many of his Irish emigrant labourers died of a virulent fever. Traversing 203 km of largely unsettled country between Kingston and Bytown (now Ottawa), and including 47 locks, the canal was opened May 24, 1832.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.