This study is a historical analysis of the effectiveness of Union cavalry during the Atlanta Campaign of the American Civil War. In a campaign noted for the highly skilled maneuver conducted by General William Tecumseh Sherman, the effective employment of the cavalry was essential. The Union cavalry had the missions of providing security to the flanks of the army and protecting the supply lines by guarding the railroad and by striking against the Confederate cavalry. Later in the campaign, the Union leadership introduced the task of destroying Confederate railroads as a cavalry mission. The Union cavalry failed to perform these missions adequately.First, this work investigates the tradition of the Union cavalry and the state of Sherman's cavalry at the beginning of the campaign. Secondly, an analysis of the cavalry operations breaks the use of cavalry into three phases and focuses on the various missions which were attempted. Finally, the study addresses the lessons learned and what the applicability is for modern operations.This study concludes that although the Union cavalry was well manned and well equipped, improper employment and deficient senior leadership caused it to play an unsuccessful and detrimental part in the overall campaign.