I presume that was Kennesaw Mountain. Sherman had been flanking the entire campaign and Johnston had obliged, but the position on KM was substantial enough to make flanking somewhat difficult and risky. The attack did result in the Federals gaining a position on the Confederate left that was dangerous to them.
Most Civil War deaths were nonbattle caused. It is amazing how many survived the crude surgeries performed back then.
I had a friend in college who was big into military history. We'd stay up all night playing boatd games that simulated various battles, and it got me interested. One was about D-Day, a pretty decent game really. The presence of the German 352nd division was unknown to the Allies above Omaha Beach and a real problem for them. The other troops were mostly static "old men" troops and one Russian battalion behind the lines that did nothing.
The failure to take Caen was regrettable, and predictable really.