From the parole records at this site -
http://www.nps.gov/archive/vick/home.htm

Sgt. T. J. McGahan of Co.H/35th. Miss. surrendered at Vicksburg on July 4, 1863.

He is listed here as Thomas Jonathan McGahey, please be aware errors can be found in this registry.

http://mscgr.homestead.com/MSCGRMcDonel.html

Hope this helps.