The hardening of Canada's attitude toward the US occurred mostly after the war, when so many Tories flocked to Upper Canada.
Bringing in Canada was a real, but missed, opportunity.
They weren't for the most part actively hostile, but they were a long way from being "brothers in arms," which was why I said George was over-optimistic.
It was attempted again during the War of 1812.After the Civil War , the Fenian efforts caused the British government to make Canada an autonomous entity with the British North America Act of 1867. But as late as 1895, Theodore Roosevelt was among those talking about the annexation of Canada. Which is one reason why during the Spanish-America War, the British started making nice and moved toward a kind of alliance with the USA in imperial matters. The Prairie provinces and even parts of British Columbia were settled by many Americans.