Manassas is a city in Tattnall County, Georgia, United States. Per the 2020 census, the population was 59. The community was named afte…Manassas is a city in Tattnall County, Georgia, United States. Per the 2020 census, the population was 59. The community was named after Manassas Foy, the son of a local citizen. The Georgia General Assembly incorporated Manassas as a city in 1920.