The War of 1812, or I love reading

[clemenceau]

Some Americans argued that the majority of the population in the British colonies would rise up and greet an American invading army as liberators, and that, as Thomas Jefferson suggested in 1812, "the acquisition of Canada this year, as far as the neighborhood of Quebec, will be a mere matter of marching, and will give us the experience for the attack on Halifax, the next and final expulsion of England from the American continent." The belief that the United States was destined to control all of the North American continent would later gain the name Manifest Destiny, but that term was not yet in use at the time of the war.
See source.

It's probably not a matter of Bush not being up on his history, but rather him not caring.