Canada fears invasion
... America wants revenge on Britain for this and they plan on doing a "Manifest Destiny" meaning that they wish to form a continental nation that includes Mexico and Canada. ... They have attempted to force Canada into annexation by imposing tariffs on imports of Canadian natural-resource products, which in turn, would weaken the economy. ... This would ensure that no civil war would break out in Canada. In 1860s, they began to get together all the colonies to start forming the Confederation of Canada.