Lightburn led his brigade during the Atlanta Campaign, seeing action at the battles of Resaca, Dallas and Kennesaw Mountain. During the Battle of Atlanta Lightburn rose to command the 2nd Division after the death of army commander James B. McPherson and all of Lightburn's superior officers rose in command also. When Oliver O. Howard was chosen as permanent commander of the Army of the Tennessee, Lightburn returned to command of the 2nd Brigade and fought at the battle of Ezra Church. During the following siege of Atlanta, he was engaged in light skirmishing and was shot in the head. The bullet merely grazed his skull but knocked him from his horse falling into the arms of his brother, Calvin Luther. The wound ended his career with the Army of the Tennessee and he was sent home to recover. Upon recovery he first commanded a brigade then the 2nd Division in the Department of West Virginia until he resigned from the army on June 22, 1865.