They used a variant of the Bowen/Missouri pattern battle flag - red field, yellow border and white Latin cross off centered. They smuggled this flag out of Vicksburg only to lose it in their wagons left on top of Lookout Mountain in Chattanooga when Hooker's Federals attacked that place. The regiment and the rest of Cumming's Brigade, had been pulled off the mountain the day before but their wagons had not yet left before the Federal attack.
The flag is held by the Georgia Department of Natural Resources.
PS - there is an August Depot flag from 1864 for the regiment in the Crown Gardens in Dalton, GA.