Sir, why do you blather such blithering nonsense?!
By April 1861 Confederates had seized by force dozens & dozens of Federal properties -- forts, ships, arsenals, mints, etc.
Far from Lincoln's "capitulation to the claim of sovereignty of the CSA", Lincoln was hoping to secure Virginia's loyalty so that he could move against secessionists, to eventually restore the Union.
FRiend, you are working, working way too hard to stretch the truth of history into places it just won't go.
Give it up!
Funny, that is just what I was thinking about you! You know you sit here and quibble about details of which Forts got abandoned, but it occurs to me that the British abandoned quite a lot of Forts. This is a normal part of what happens when one part of a nation separates from another.
Why should one country maintain forts inside of another against that nation's consent? Did we not abandon our Military bases in Iran? How about the Philippines? That was once ours, but we let it go and we sought and got leases to remain, but when they wanted us out, we left.
Same thing with Cuba. Pity we couldn't show the same courtesy to people who were our wrong headed kinsmen.