In the opening move of the campaign to take Atlanta, Union General William T. Sherman ordered General George Thomas’s Army of the Cumberland to move against General Joseph E. Johnston’s Confederates entrenched along Rocky Face Ridge. While Thomas’s force attacked Johnston, General James B. McPherson’s Union Army of the Tennessee would march south toward Resaca and threaten the Confederate rear. On May 8, 1864, Union troops under General John W. Geary advanced up the steep slopes at a place called Dug Gap. Geary’s men, many of whom had scaled Lookout Mountain six months earlier, reached the Confederate line. Hand-to-hand fighting broke out along the craggy mountain crest as daring Yankees vaulted over rocks and boulders to break the Rebel line. Ultimately, Confederate reinforcements under the command of General Patrick Cleburne arrived on the scene and successfully drove the Federals back down the mountainside. Though, the first battle of the Atlanta Campaign had been a victory, McPherson’s march went undetected. Sherman’s move to take Atlanta was well underway.