Fort Ticondaroga was badly situated for defense against land based forces. It was located to interdict southern Lake Champlain (supplemented with a iron and log chain) near the confluence of the river from Lake George. The British took it with minimal bother (Burgoyne’s expedition) by occupying a lowish mountain nearby. The French defended it successfully once (under Montcalm) by leaving the fort and building field fortifications.
At that time reducing a masonry fortress was a textbook exercise: You selected where you wanted the breach, you dug or blasted parallel trenches that could not be enfiladed until you got close enough to pound a breach in the wall. It wasn’t fast, but it was sure. A relief party could arrive and rescue the garrison of the fort, but it couldn’t hold the fort against a siege. Forts could not be held, but served only to delay. Vauban developed them to guard military stores, and to delay enemy forces while other forces were mobilized and trained.
Ft Sumter was admirably placed to prevent digging parallel trenches. There was no South Carolina soil adjacent to Ft. Sumter upon which parallel trenches could be dug. Still, Ft. Sumter could protect a harbor from attack on the water, but it could not be held against a superior land force.
In this discussion, Fort Ticondaroga is merely an example of a Fort which could have been held by the British, and it's importance is for nothing more than to illustrate a point. The founders would have likely regarded continuing British occupation of a Fortress on American land as an unacceptable situation, though they would probably have had more sense than to provoke the British into an all out retaliation.