Fearing envelopment, Confederate Gen. Joseph E. Johnston withdrew his army to a new defensive position astride Kennesaw Mountain, to the north and west of Marietta. Johnston selected this position in order to protect his supply link to Atlanta, the Western & Atlantic Railroad. Prior to taking up this new line on June 19, Johnston had pioneers working through the night digging trenches and erecting fortifications, turning Kennesaw into a formible earthen fortress. Having defeated Gen. John B. Hood troops at Kolb’s Farm on the 22nd, Union commander 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 9AM on June 27. 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. 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 generals Charles Harker and Daniel McCook.