Fort Moultrie was abandoned by Major Anderson, it's cannon's spiked and their carriages set on fire. The Southern people surrounding the fort had believed that the Fort would be turned over to their officials in due course, and regarded the destruction of the cannons as a belligerent act which indicated to them that they were to be regarded as an enemy by the Federal authorities.
It was the first indication to them that they would be regarded in a hostile manner.
Also, you may not realize that the granting of Ft. Sumter to the Federal Government was conditional, and that the Federal Government defaulted on the conditions decades before the Civil War ever started.
That, if the United States shall not, within three years from the passing of this act, and notification thereof by the governor of this State to the Executive of the United States, repair the fortifications now existing thereon, or build such other forts or fortifications as may be deemed most expedient by the Executive of the United States on the same, and keep a garrison or garrisons therein, in such case this grant or cession shall be void and of no effect.
It wasn't completed in the three year time limit (it wasn't even completed by 1861) and it wasn't garrisoned until Anderson moved into it.
The legal point here is that the US Government was in default violation of the conditions which would have allowed them ownership of the property.
Actually I don't know that. When is the date on the document you quoted and the document itself so we can see the quote in context?
The legal point here is that the US Government was in default violation of the conditions which would have allowed them ownership of the property.
No they weren't. Not according to this legislation passed on December 31, 1836 - Link