01 A defensive work
After the War of 1812 one vulnerability was clear: the supply route between Montreal and Kingston followed the St Lawrence River, which along much of its course formed a border and lay exposed from the opposite bank. A single blockade could cut off supply to the interior.
The solution was to open an alternative inland route, joining the Ottawa River with Lake Ontario through existing lakes and rivers. The commission went to Lieutenant-Colonel John By of the Royal Engineers, and work began in 1826.
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02 Six years and forty-seven locks
The canal was completed in 1832: 202 kilometers between Ottawa and Kingston, with forty-seven locks across twenty-three stations. The technique chosen was slackwater — damming existing watercourses to make them navigable rather than digging a new channel end to end.
The human cost was high: crews worked in swampy ground and disease caused many deaths among the labourers, most of them recently arrived immigrants. The camp that housed that workforce is the origin of the city.
03 Why it remains unchanged
The attack it was built for never came, and the canal never saw combat. It moved straight into civilian use: carrying timber and grain through the 19th century and, once the railway took its commercial traffic, pleasure boating.
That trajectory explains its condition. Never strategic and never profitable, it was never modernized: the locks are still worked by hand and the route is the original one. That is why Unesco inscribed it in 2007 as the best-preserved example of a slackwater canal in North America and the only early 19th-century one still operating along its original route.
- Walk down the flightThe stretch between downtown and the river takes ten minutes on foot and explains the drop better than any map.method
- Go when the locks are workingFrom May to October you can watch the gates in operation, worked by hand cranks.season
- Visit the canal museumThe 1827 stone commissariat beside the locks is the oldest building in the city.context
04 New understanding
Understanding the origin changes what you look at. The locks stop being a picturesque downtown detail and become what they are: a piece of military engineering built by hand in six years, in territory then almost empty, for a scenario that never happened.
And it leaves a paradox visible in the landscape itself: the city that is now the capital was born as housing for that project. Without the canal there would be no Bytown, and without Bytown no Ottawa.
