Uncharacteristically, Sherman attacked the strongest portion of Johnston's line, the twin peaks of Kennesaw Mountain. Not only were the rebels deeply entrenched, but their artillery was dug in on the crests of the mountains. The result wasn't a battle, but butchery.
3,000 of the 12,000 attacking Federals were shot down in the southern heat. Johnston lost around 500. Sherman wired General Thomas - the "Rock of Chickamauga" and perhaps his best subordinate - to ask if another assault would give favorable results. Thomas replied with the words in the title of this post.
Billy Sherman was perhaps the most cold blooded of the Union generals, and his assessment of his failure was entirely in that vein. Shelby Foot describes his post-mortem of the battle:
"This assault I made was no mistake; I had to do it," he wired Halleck, explaining that after nearly eight weeks of gingerly skirmishing, all the time conforming to a pattern about as precise as if he and Johnston were partners in a classic minuet, Federals and Confederates alike "had settled down into the conviction that the assault of lines formed no part of my game." Now that both sides knew better, having seen the dance pattern broken as if with a meat axe, he expected to find his adversary "much more cautious."#2 Son and I are off to see the battlefield, which is only a half hour's drive ("Take Marietta Highway west to the Big Chicken, then head north until you see signs for the park.") It's a far prettier day than that one in June when the mountaintops were wreathed in black powder smoke.
Sherman resumed his flanking, which led him here to Rowsell where they burned the mill before forcing a crossing under fire across the Chattahoochee. They still hate him here; it wasn't the butcher's bill in that terrible conflict, rather it was how he made war on the women and children in his path. 400 women were working in the Roswell textile mill, and he sent them all north to concentration camps in boxcars.
That's one cold SOB.