The fifth battery was the largest and called Battery Holmes which also had a bombproof magazine and was at the southernmost point of the island.
Construction began in September 1863 and continued into 1864. It guarded the east side of Old Inlet (Fort Caswell was on the west). The flagstaff was located on the Bald Head Promontory.
It was mostly destroyed when the Confederates evacuated after the fall of Fort Fisher.
GENERAL THEOPHILUS H. HOLMES
It was named for Confederate General T. H. Holmes who graduated from the United States Military Academy in 1829 and was a career soldier. Before the war, he commanded Fort Columbus on Governor's Island in New York Harbor.
He resigned his commission after secession and became a colonel in the Confederate Army and commanded coastal defenses in the Department of North Carolina, later becoming a brigadier and major general.
I was unable to find any mention as to how much of Fort Holmes is still standing.
The Fort on the Island. --Old B-Runner
The Battle of Fort Fisher, N.C.
