An illustration of Atlanta, Georgia as depicted in 1874. Atlanta, GA is the capital and the most populous city in the state of Georgia. During the American Civil War, Atlanta served as an important railroad and military supply hub. In 1864, the city became the target of a major Union invasion. The area now covered by Atlanta was the scene of several battles. The rebuilding of the city was gradual. From 1867 until 1888, U.S. Army soldiers occupied McPherson Barracks in southwest Atlanta to ensure Reconstruction era reforms.