Ifg there was a formal deed, it should be recorded in the office of the Register of Mesne Conveyances. That doesn't mean it was! The Register's address: Charles Lybrand, RMC, Charleston County Court House, 101 Meeting Street, Charleston, S. C. 29401-2249. Telephone (843) 958-4800. Some of their old deed books may have been transferred to the S. C. Department of Archives and History. If they have transferred the deed books from that period, they can give you the number.

Having said this, I am of the impression that the fort was built on a rock or reef which was not covered at high tide, and thus would not have been privately owned. If that is the case, there would have been not a deed, but perhaps the State gave some sort of consent. Any such document would be at the State Archives.