Nope! Fort Sumter was ceded to the Federal government early in the nineteenth century. South Carolina ceded it to the United States. On December 17, 1836, South Carolina officially ceded all “right, title and, claim” to the site of Fort Sumter to the United States.
Also South Carolina which had owned multiple forts, namely Fort Moultrie, Castle Pinckney, and Fort Johnson ceded them, along with sites for the future erection of forts, to the Federal Government in 1805.
The proper course of action would have been to purchase the property or properties back.
Note I will not participate any further in these “count the angels dancing on the head of a pin” Civil War discussions.
Nope! When South Carolina seceded they could under their eminent domain power claim any land within their sovereign territory just as any country (or state) may.
the Confederate states DID send a delegation to Washington DC to negotiate a reasonable separation agreement where issues of property and assets and apportionment of the national debt, etc would be worked out. They made a good faith effort. It was the Lincoln administration which refused to meet with them.