The original transfer was a legal document in which the state of South Carolina ceded all ownership of the property to the United States without condition other than those providing for the serving of civil or legal warrants on people in the fort. The U.S. government did nothing to violate these provisions so the South Carolina government had no legal basis for reclaiming the fort. They had no claim to property that they did not own.
No. It wasn't.
Yes it was. You have demonstrated nothing except that both letters gave, as the primary purpose of the expedition, the peaceful landing of supplies only and that force was to be used on if such a landing was opposed.
It was a legal statute. Statutes can be repealed by their originator - even those that claim to be unrepealable. South Carolina repealed its statutes with the United States by act of secession. That would seem to include the Fort Sumter statutes.
Yes it was. You have demonstrated nothing except that both letters gave, as the primary purpose of the expedition, the peaceful landing of supplies only and that force was to be used on if such a landing was opposed.
Wrong. I have demonstrated that one used active and conditionally explicit language. The other used passive and intentionally vague language. One said "if they don't let you in you are to open fire right then and there." The other said effectively "Let us in and we aren't going to open fire anytime soon." If you cannot see the difference between those statements then you are dishonest, willfully obtuse, or just plain stupid.