As with any State in the Union, Georgia is divided into Senatorial and Congressional Districts for the election of State Senators and Representatives. These districts were also used to when counting the census and organize the State Militia. During the war Georgia utilized no less than three schemes using the Senatorial districts to organize and re-organize the militia. You ancestor was in the 18th Senatorial District. These districts were divided into militia districts. There were over 1100 such districts in Georgia during the war. Your ancestor was in Military District 1077. Each district would raise a company of militia (because some districts were too small, two or three districts would combine to raise a company). These militia companies were not as well organized as the regular army. These militia companies didn't even have uniforms. They really didn't see much military action. If they did anything during the war it was to act as local police, help confederate widows, and harvest crops. If any additional information exists on your ancestor at the GA Archives it will be in their original documents, which they do not search when you request information from them.

Sincerely,
Mike