The book, Nothing But Glory, by Kathy Georg Harrison and John W. Busey lists the following under Company C, 11th Virginia in Pickett's Division at Gettysburg (on 3 July 1863). Evidently the information on Leslie being exchanged is not entirely accurate:

Blankenship, Charles T.: Farmer; captured; exchanged from Chester Hospital [in Pennsylvania] (apparently sick) 23 September 1863.
Blankenship, Leslie C.: Enlisted 18 March 1862 at Lynchburg; captured; exchanged sometime after August 1864.