Continuous rains in June--Allatoona made a field depot on the railway and fortified--Johnston in the Marietta lines--That from Pine Mountain to Lost Mountain abandoned--Swinging our right flank--Affair at Kolb's farm--Preparing for a general attack--Battle of Kennesaw--The tactical problem--Work of my division--Topography about Cheney's--Our advance on the 27th--Nickajack valley reached--The army moves behind us--Johnston retreats to the Chattahoochee--Twenty-third Corps at Smyrna Camp-ground--Crossing the Chattahoochee at Soap Creek--At Roswell--Johnston again retreats--Correspondence with Davis--Mission of B. H. Hill--Visit of Bragg to Johnston--Johnston's unfortunate reticence--He is relieved and Hood placed in command--Significance of the change to the Confederacy and to us. In the month of June we had more than three weeks of pouring rains, making a quagmire of the whole country. The "dirt roads," which were the only ones, were soon destroyed by the heavy army wagons, and even the place where they had been could not be distinguished in the waste of mud and ruts which spread far and wide. Sherman found the intrenchments Johnston had left "an immense line of works," and congratulated himself that they had been turned with less loss to himself than he had inflicted on the enemy. [Footnote: Official Records, vol. xxxviii. pt. iv. p. 408.] The first reconnoissances found that Johnston had retreated so far that, from the commander downward, we all harbored the hope that he had retreated beyond the Chattahoochee. [Footnote: _Id_., p. 427.] To prepare for our next step, the railway crossing of the Etowah must be completed and our depot of supplies advanced to Allatoona. The gorge there was almost as defensible on the south as on the north, and Sherman set Captain Poe, his engineer, to work laying out fortifications to cover its southern mouth and thus prepare for holding it by a small garrison as a secondary base if we should have to leave it again to make a wide turning movement. [Footnote: Official Records, vol. xxxviii. pt. iv. p. 428.] [Illustration: Vicinity of Marietta, June 20,--July 4, 1864.] We were not long in learning that Johnston was not over the Chattahoochee, but had only fallen back to a shorter and more formidable line about Marietta, covering the railway where it passed through the defiles of Kennesaw Mountain, extending his left centre to the isolated knob of Pine Mountain, and thence recurving his flank by way of Gilgal (Hard-Shell Church in local nomenclature) toward Lost Mountain, which was held by his cavalry.