Even with all his army present Sherman, himself, hesitated to attack Johnston in his works--a fact which seems a sufficient answer to that criticism of McPherson which has been freely exploited in writings concerning this campaign. Sherman, however, had so greatly the advantage of Johnston in numbers that he could afford to send large detachments against the Confederate general's communications, while still holding a threatening position of his own in front. This he did with consummate skill, forcing Johnston with his small army to retreat southward following the railroad, and destroying as he went. Johnston left Resaca on the night of the fifteenth of May, and on the nineteenth took position at Cassville, where he seemed to offer battle to his enemy. But after some sharp skirmishing the Confederate general retreated again during the night of the twentieth to a point south of the Etowah river and to Alatoona. After a few days of rest and reprovisioning, Sherman moved again, not directly against his antagonist, but by the flank, so as to threaten Marietta and Atlanta itself, which lies only a few miles south of Marietta. By this movement Sherman hoped to force Johnston to abandon his strong position at Alatoona Pass, where he securely held the railroad over which Sherman had need to bring his supplies in any further advance that he might make southward. Promptly recognizing the purpose of this movement, Johnston marched westward to assail his enemy in flank. The two armies met at New Hope Church, a point a few miles west of Marietta, and a few miles northwest of Atlanta. Here for six days there was continuous and very bloody fighting, both armies doing their work in a fashion that rivaled even that of the contending forces in Virginia. By virtue of his superior numbers, Sherman was able to make strong detachments to assail the communications and the flanks of Johnston's army, and thus to compel him to fall back again to a strong defensive position on the railroad above Marietta, on Kenesaw, Lost and Pine Mountains. Against this position Sherman advanced with caution, strongly entrenching himself in its front. There the fighting was continuous and costly of human life on both sides. There it was that General Leonidas Polk, Protestant Episcopal Bishop of Louisiana, who had been educated at West Point for the military service, but who had afterwards risen to the highest place of honor in his church as a Bishop, and had at the outbreak of the war entered the Confederate service in which he had risen to the rank of major general, was instantly killed by a cannon shot which Sherman himself had directed to be fired into a group of Confederate officers of whom he caught sight on a hill. This was on June 14.