Fearing envelopment northwest of Atlanta, Confederate Gen. Joseph E. Johnston withdrew his army to a new defensive position astride Kennesaw Mountain near Marietta. Johnston selected this position in order to protect the Western & Atlantic Railroad, his supply link to Atlanta. Prior to taking up this new line on June 19th, Johnston had pioneers working through the night digging trenches and erecting fortifications, turning Kennesaw into a formidable earthen fortress. Having defeated Lieut. Gen. John B. Hood's troops at Kolb’s Farm on the 22nd, Union commander Maj. Gen. William T. Sherman was convinced that Johnston had stretched his line too thin and, therefore, decided on a frontal attack on the Confederate bastion. After an intense artillery bombardment, Sherman sent his troops forward at 9:00 am on June 27th. Determined Yankee assault troops came to within yards of the Confederate trenches, but were unable to break the Southern line and by 11:30 the attack had failed. During the fighting, Confederate Gen. Leonidas Polk, the "Fighting Bishop" was killed. Sherman, who later dubbed the battle as "the hardest fight of the campaign up to that date," lost roughly 3,000 men in the contest, including brigade commanders Brig. Gen. Charles Harker and Colonel Daniel McCook. The tactical Confederate victory failed to deliver the result that the Confederacy desperately needed—namely a halt to Sherman's advance on Atlanta.