[Non-Sequitur]

Lincoln maintained a fort within the territory of South Carolina, a State that considered itself seceded and no longer part of the United States, thus this was a foreign military facility. That would normally be considered justified

So would Castro be justified in bombarding Guantanamo Bay into surrender? What should the U.S. do if he did?

The people of South Carolina took back only the property they had originally ceded the Federal government.

What legal right did they have to do so?

Perhaps if he HAD withdrawn, an accommodation could have been reached, but frankly, both sides were spoiling for a fight.

Having surrendered to Southern demands what accommodation was necessary? The South would have seized what they wanted. What else was there?

[FredHunter08]

“So would Castro be justified in bombarding Guantanamo Bay into surrender? What should the U.S. do if he did?”

He could try. Of course, Cuba had not had previous history as one of the owners of the Federal Government.

“What legal right did they have to do so?”

What legal right did they not have to do so? What legal power was granted Lincoln to keep them in the Union?

“Having surrendered to Southern demands what accommodation was necessary? The South would have seized what they wanted. What else was there?”

Let them go. All that was required.

[beckysueb]

What legal right did they have to do so?

The Constitution?