The Treaty of Paris recognized the sovereignty of each of the 13 colonies individually. The states did not surrender their sovereignty when they ratified the US Constitution. Once again, this is a lie on your part not supported by any of the writings at the time and not supported by numerous SCOTUS decisions right up to the present day which recognizes the sovereignty of the states.
If it were true that South Carolina in 1860 had "sovereign territorial waters" to defend, then you might expect at least a SC Coast Guard or Navy, but of course there was none.
South Carolina like the rest of the Confederate states had only recently seceded and had not had time to construct a navy yet.
South Carolina's territorial waters were the responsibility of Federal government, not South Carolina.
While South Carolina was in the US. Once it seceded that was no longer the case.
But not one ever did on April 11, 1861.
They had already invaded South Carolina's sovereign territory and were threatening to do so again with a heavily armed fleet of warships.
Perhaps, but not one of those ships ever "invaded" South Carolina's "sovereign territorial waters".
But others already had and this fleet of warships was sent specifically to invade South Carolina's territory as the South Carolinians well knew.
No, because we are talking about degrees of sovereignty here, and it is simple fact that after ratification in 1788 under the new US constitution, states were less sovereign than they had been previously.
FLT-bird: "South Carolina like the rest of the Confederate states had only recently seceded and had not had time to construct a navy yet."
Nor did it ever, since that was a function of Federal government.
FLT-bird: "They had already invaded South Carolina's sovereign territory and were threatening to do so again with a heavily armed fleet of warships."
But in fact, they never did, and their orders were not to, so long as Confederates remained peaceful.
And so your whole meme about a Union "war fleet" invading South Carolina's "sovereign territory" is babbling nonsense.
It never happened, nor was it necessary to trigger Jefferson Davis to order Fort Sumter be "reduced" by Confederate artillery.
Davis, by his own confession, intended to start Civil War at Forts Sumter and Pickens regardless of what Lincoln did or didn't do.
And the reasons are not in the least difficult to understand.
Secession is illegal under the 14th. Amendment.