[x]

Do you think we had the attitude that the British forts and/or any land within the States belonged to England on or after July 4, 1776?

Funny you should mention that.

The Revolution ended in 1783 with the Treaty of Paris. The British didn't leave Fort Detroit until 1796, after Jay's Treaty was ratified, even though Detroit was in US Territory after the Revolution. Same thing with Fort Mackinac.

We didn't go to war with Britain over that, though. One reason was that Indians controlled the land US troops would have to cross to get to the forts, but still, we weren't as given to saber rattling as the secessionists were.

FWIW, Trudeau (and Cruz) don't appreciate the author's ripping off Moulson's "I am a Canadian" speech.

[BroJoeK]

x: "The British didn't leave Fort Detroit until 1796, after Jay's Treaty was ratified, even though Detroit was in US Territory after the Revolution.
Same thing with Fort Mackinac."

Thanks ml/nj, rockrr & x for bringing this subject up again, since I've long searched for a complete listing of those.
Now, by my count there were at least eight British forts in four US states & territory from the time of the Treaty of Paris in 1783 until the Jay Treaty in 1796 -- 13 years!

In New York:

1. Fort Niagara
2. Fort Ontario
3. Fort Oswego
4. Fort Oswegatchie

In Michigan:

1. Fort Mackinack
2. Fort Detroit
3. Fort Lernoult

In Ohio: Fort Miami
In Pennsylvania: Possibly Fort Presque Isle (?)

This map also shows several other British forts in the US during that time, but so far I can't find verifications for all of them:

The subject can get confusing since some reports say the Brits were still in Fort Mackinac in Michigan during the War of 1812, and you have to look elsewhere to learn that they did indeed abandon that fort in 1796, only to reoccupy it after President Madison declared war in 1812.

Another questionable fort is Presque Isle in Pennsylvania, which is listed in the Treaty of Paris link, but not on the Jay Treaty link.
Interestingly for this discussion on Fort Sumter is the fact that Fort Miami in Ohio was built by the Brits after they promised to leave in 1783, only finally abandoned in 1796.

Again, the point of all this discussion is: a foreign power having forts on US territory, even after they've promised to leave them, was not considered a casus belli by our Founding Fathers.
Instead, they patiently waited for negotiations to resolve those forts, 13 years later.