Why did the Americans not also (or instead) try to take over what is now essentially southern Ontario? It was decent land, sparsely settled at the time, and ‘easier’ to invade (closer with more forgiving terrain)? Was it even considered?
I remember watching documentary series about the War of 1812 in Canada the last couple of winters (you can probably find them on line). Seems to me there were attempts by both sides to invade each other’s territory in the region (the British took Detroit, the Americans burned the Government Houses in what’s now Toronto), but the whole affair was kind of a half-hearted effort: the British could never muster the ground forces in North America to inflict a decisive defeat on the United States (Napoleon’s France was a much greater concern), and the US Army (never that strong to begin with) just wasn’t up to the task either. (As I recall, it was quite poorly led.)
The United States was very lucky indeed that the British were ineptly led at New Orleans in January 1815, otherwise they might well have gained a new foothold in the interior of North America (even though the Treaty of Ghent had been signed the month before).
This - in 1780 there was really nothing there. Of course, even the 13 colonies barely extended past the line of the Appalachian mountains at the time. A lot of the major expansion happened after the revolution; at which time, as Nemo says, the area of southern Ontario was being settled by a lot of people who had found it prudent to leave the USA due to their politics.
The colonials were too busy fighting actual battles with actual soldiers to waste manpower to occupy what was essentially an empty forest.
They did try to take Quebec, which was an actual settled area with a British garrison; but after a winter siege (IIRC) that got nowhere, left and gave up. If they had taken that, then Ontario would be theirs by default.
Also, keep in mind that the land that now forms Southern Ontario (along with much of the upper U.S. Midwest) had been an “Indian Reserve” until just a couple of years before the U.S. Revolutionary War. The Crown had ceded the land to the natives after Pontiac’s rebellion, and had only given it over to the province of Quebec in 1774. This lends credence to the position that there’s nothing there that would have been of interest to the Continental Army.
Besides, if they had taken the land, what then? You’ve got a bunch of men sitting all the way over in Ontario who need to eat. Your supply lines are running huge distances overland — even if you can navigate up the St. Lawrence, Quebec City & Montreal are still held by the British, so that’s a no go. It seems like a lot of trouble for not very much reward.
I think the biggest answer was that it didn’t really have much value. What was there, they already had plenty of, plus there were still hostile Indians there. I think that if they were truly motivated they could have had it, but the costs weren’t worth the reward.
http://en.wikipedia.org/wiki/Oswego,_New_York - This suggests the Americans had trouble even holding onto Fort Oswego for more than a short time, effectively meaning they would not easily support an invasion with supplies across lake Ontario. (a little short on detail)