After the Battle of Kennesaw Mountain, the muddy roads dried, allowing Sherman to return to his flanking strategy. On July 2, Johnston's Confederate soldiers abandoned their Kennesaw lines for other prepared defenses at Smyrna and then to the Chattahoochee River, only to have the larger Union army go around them each time. (nps)
Confederate President Jefferson Davis, dissatisfied with Johnston's retreats, replaced him with the combative Lt. Gen. John Bell Hood. With the Union army closing in on Atlanta, Hood went on the offensive with his beleaguered Confederate army. (nps)
Sherman's army severed Atlanta's railroads with victories against Hood at Peachtree Creek, Atlanta, Ezra Church and Jonesboro. The city's capture on Sept. 2 was a bitter blow to the Confederacy. (nps)
On the Union side the campaign for Atlanta was, as Grant declared in a telegram of congratulations to Sherman, "the most gigantic undertaking given to any general in the war." Sherman owed his success mainly to Confederate mistakes, to not making any irreperable blunders of his own, and above all to the superior power and high quality of his army, which he maintained by not, like Grant in Virginia, repeatedly engaging in bloody offensive battles designed to knock out the enemy with one mighty blow but instead employing flanking moves to compel the Confederates to abandon one strong position after another and finally Atlanta itself. (Castel 55)
Sherman's sole major failure, one stemming from his concept of warfare and a fixation with capturing Atlanta to the near exclusion of all other objectives, was not to take advantage of the numerous opportunities he had to destroy the opposing army in Georgia or mangle it so badly as to render it strategically impotent. As a consequence, Hood's forces, although badly battered, remained a source of danger and trouble until Thomas finally smashed them at the Battle of Nashville in December 1864. (Castel 55)
But if Sherman failed to do as much as he could and should have done, he accomplished what he set out to do and had to do: take Atlanta. And in doing that he guaranteed the North's victory by depriving the South of its last chance of winning--of winning by not losing. (Castel 55)