I do not know the name of the officer and will have to get that book and check it out. Thank you for the lead. I have a few letters still to transcribe from Federal soldiers written from Mustang Island in December shortly after the fight at the Fort of Nov.17 ,1863. No mention of the officer that I see from a quick scan of the letter from the 20th Iowa soldier.
Robert Mercer and his sons were living on this part of the island before the war. The old channel has moved to the south over the years and as I understand it, the actual location of the Ft Semmes is about now where the Lydia Ann Lighthouse is.