The American War of Independence (1775–1783) revealed a number of serious flaws in the British defence system. The western frontier of the Canadian colony was protected by the military outposts on the Great Lakes. However, these outposts were all the more vulnerable for being difficult to reach. Troop and merchandise transport via the Saint Lawrence River was seriously slowed by the rapids located upstream from Montreal. In particular, the rapids at Coteau-du-Lac were the most difficult to get past and skirting the rapids by going inland prolonged supply times. To accelerate shipment of military supplies westward, Governor Frederick Haldimand ordered for a canal to be dug at Coteau-du-Lac.