The Rideau Canal, a monumental early 19th-century canal covering 202 kilometres of the Rideau and Cataraqui rivers from Ottawa south to Kingston Harbour on Lake Ontario was built primarily for strategic military purposes at a time when Great Britain and the United States of America vied for control of the region. The property, one of the first canals to be designed specifically for steam-powered vessels, also features an ensemble of fortifications. At the start of the project, in 1826, the British chose the so-called "slackwater" technology to avoid the need for extensive excavation. Instead, a series of dams were built to back up river water to a navigable depth and a chain of 50 massive locks were created. It is the best preserved example of a slackwater canal in North America demonstrating the use of this European technology in North America on a large scale. It is the only canal dating from the great North American canal-building era of the early 19th century to remain operational along its original line with most of its original structures intact. The canal was protected by the construction of six ‘blockhouses' and a fort. Defensible lockmaster's houses were later added at several lock stations and, between 1846 and 1848 four Martello towers were constructed to strengthen the fortifications at Kingston harbour. The Rideau Canal is of historical importance as it bears witness to the fight for control of the north of the American Continent.
