Sherman was also fortunate to face Joe Johnston as his willing opponent. It would be interesting to speculate how Sherman's flanking strategy would have played out had he been facing Lee in Georgia. As we all know, Grant tried a similar flanking strategy in his Overland Campaign but wily and aggressive Lee was able to put up a formidable defense. But of course, Grant did end up crossing the James River and besieging Petersburg as Sherman did in crossing the Chattahoochie River and besieging Atlanta.
As far as Kennesaw goes, there are also similarities to Grant's ill-fated frontal assaults at Cold Harbor. In both cases, the Union commanders had just about run out of space to maneuver, and deemed the time had come for more assertive actions that could deal devastating blows to the enemy. But to give Sherman a little more of a pass on his decision to attack at Kennesaw, it should be noted that Johnston, over the preceding days, had prepared and had fallen back along strongly entrenched lines in the rugged terrain of Lost, Pine, Brush, and Kennesaw Mountains, thereby further suffocating Sherman's efforts to carry out effective flanking movements.