Thus Johnson abandoned his lines at New Hope Church and retreated to Marietta, taking up almost impregnable positions on Kenesaw, Pine and Lost Mountains. Sherman marched to Ackworth, between Marietta and Allatoona Pass, and fortified the Pass. He was here reinforced by two divisions of the Seventeenth Corps and some other bodies of troops, which nearly compensated him for the losses in the battles he had fought. He had now driven Johnston before him nearly one hundred miles, had forced him to abandon four strong positions, had fought him six times, had captured over two thousand prisoners, twelve guns and three colors, had weakened the Rebel army by about fifteen thousand men, and had captured or destroyed many important factories, mills and other works of a public character. [Illustration: DEATH OF GEN. J. B. McPHERSON. JULY 22D, 1864. From Painting by J. E. Taylor.] The line held by Johnston at Kenesaw and Pine Top was a strong one. But it was twelve miles long, and he had scarcely enough men to hold it at all points. To attack him on the crest of Kenesaw Mountain would be a hopeless task. But Sherman thought he could break through his lines on the gentler southern slope. On June 11th the advance began. Hooker was at the right front and Howard at the left front, and they pressed forward with great vigor. During their cannonading, on June 14th, they inflicted heavy losses upon the enemy, killing General Polk. Next day the Rebels abandoned Pine Mountain and retired to Muddy Creek, holding the rugged range of hills between Kenesaw and Lost Mountains. Again Sherman pressed the centre and turning to Johnston's flank on the 17th captured Lost Mountain and all the hills except Kenesaw. For three weeks thereafter the Union army vainly sought to dislodge Johnston from the heights of Kenesaw. It seemed an impossible task. The whole mountain was a fortress. There were miles of strong intrenchments. All the time the rain fell in torrents and the low lands were flooded. The roads were almost impassable. Sherman's soldiers at times worked knee deep in mud. But they kept on working. The army was not content with besieging Kenesaw, but kept trying to work its way around that mountain. Disquieted by these events, the enemy sought to check them on June 22d, by a sharp attack upon Hooker at Kulp's farm, which was repulsed with heavy losses. Five days later, the 27th of June, Sherman ordered an attack to be made just South of the mountain, by Thomas, and a supporting movement by McPherson northward. They were both repulsed with heavy losses, and Sherman then decided to waste no more lives in direct attacks, but to turn the enemy's position, as he had done several times before. So on July 1st, McPherson marched toward Turner's Ferry, there to cross the Chattahoochee. The movement was effective. Johnston immediately abandoned Kenesaw, and retreated five miles, to Smyrna Camp Ground.