George was probably the son of Thomas and Anna Mullenix (variously spelled Mullinix, Mulenax, Mullinax) who had come from South Carolina and lived in Lumpkin County, Georgia. He and his younger brother, Elijah V., enlisted in the "Dahlonega Volunteers," 1st Georgia Regiment Volunteers, Company H, in 1861 and were mustered out in 1862. They then joined Company D of the 1st Georgia State Troops in January 1863 but are not part of any found roster after May 1864. Elijah was said to have deserted.