Neil; from muster records it appears that Company A 68th USCT was in the vicinity of Memphis TN in Nov of '64. One entry indicated Fort Pickering which matches NPS unit activity summary. It appears the Regiment was involved with Smith's expedition to MS during the summer but was back in Memphis by late fall. I went to Fold3 and looked up the unit and searched for 68th usct and ran down muster cards by browsing for Co A then looking for Nov 64 in individual records. Seems to have worked even if a bit laborious.
FWIW John R