"It is absurd to suppose we will not succeed. We have Canada as much under our command as Great Britain has the ocean ... The conquest of Canada is in your power. I trust I shall not be considered presumptuous when I state what I verily believe: that the militia of Kentucky are alone competent to place Montreal and Upper Canada at the feet of Congress." - Henry Clay
One could imagine that Mr. Clay's confidence had dwindled after the Americans' failed attempts to bring Ontario (Upper Canada) and Quebec to heel. The costly battles at Queenston Heights and Lundy's Lane helped finally decide a Canadian victory. Though it was not the first time the Americans had attempted to invade Canada (they attempted to take over Quebec during the Revolutionary War), this time around proved not only Britain's willingness to keep Canada but Canadians' ability to defend their homes.
The American invasion of Canada had failed.
A good thing, too.