How many times has the US invaded Canada?

Answer 1

There were a lot of conflicts in the colonial period: King William's War, Queen Anne's War, King George's War and the French and Indian War. These weren't really the "US" invading "Canada", though, since neither of them really existed at the time... it was more an issue of the British Empire (from its colonies) invading the French Empire's colonies.

Revolutionary (i.e., US) forces invaded Canada (which was by this time also a British colony) in the American Revolution. Also, the US (proper) invaded portions of Canada in the War of 1812.

A group of American rebels calling themselves the Hunter's Lodge invaded Canada in the Patriot War (1837-1838), though this wasn't really the "US" invading Canada, because the US governmentwas actually on the same side as Canada this time.

There were some border tensions about the location of the US/Canada border in the Pacific Northwest ("The Oregon Question"). There wasn't ever an actual "invasion" per se, though there were some local skirmishes ("The Pig War"), most of which amounted to no more than posturing and sabre-rattling (the only casualty of the Pig War was a British pig, shot by an American farmer when he discovered it eating his potatoes).

Around the same time, there were the Fenian Raids, which was an invasion of Canada by the Irish. Well, specifically, the Fenian Brotherhood, a US-based group of people of Irish descent. These, like the Hunter's Lodge in the Patriot War, weren't officially sanctioned by the US government (though unlike in the Patriot War, the US wasn't actually fighting against Fenian Brotherhood, and may even have tacitly approved of their actions because of the Oregon Question).

There was also a long standing disagreement as to the exact boundary between Canada and Alaska ("Alaska Boundary Dispute"). This was settled peacably by arbitration in 1903 and no actual "invasions" were performed.

Finally, there was an incident, though not an "invasion", caused by a US warship (the USS Nashville) which sailed into the Great Lakes via Canada while disarmed, and then was subsequently re-armed, technically a violation of the nearly 100-year-old Rush-Bagot Treaty (US/Canada relations had become considerably more cordial in the interim, so the US didn't think the Canadians would have a problem with it and didn't bother to ask. Oops.). This was also settled amicably by the International Boundary Waters Treaty of 1909.