And those opinions are just as irrelevant. See the federal and state laws governing the transaction for the truth.
"The feds stopped construction of the fort until clear title was conveyed. That was in 1841."
So, your post of an act of the SC state Senate in 1836 that you asserted settled the matter, didn't after all, did it.
"But a great many people thought it was U.S. property in 1861 too"
The people at the federal installations could use the property as long as they abided by the regulations outlined in the cessation documents. Those regulations were violated in 1860.
At that time the state of SC and later the Confederacy sent commissioners to Washington to secure and pay for the federal facilities. Lincoln stubbornly refused to see them and peacefully resolve this conflict. His stupidity cost the lives of over 620,000 people.
Do you have any documentation that suggests that the cessation documents were referenced at all in 1861?
Walt