A very interesting post of your ancestor's record.
The surname is not one that I have come across before. I notice two others who served TN; A.H.Cresap was in the TN 12th infantry, and V.A. Cresap was in the TN 18th Cavalry. Also possible, a C.J.P.Cresap served the CS Gen. & Staff (his home state not mentioned).
Since we get to see so few images of uniformed TN soldiers, how about posting his picture here for us to enjoy? TNX