Just to be fair to both sides General Von Moltke was quoted about three hundred or so years ago depending on the German to English translation " no plan survives the first shot" or " no plan survives contact with the enemy".What do people think was the biggest mistake of the war in terms of bad tactics and loss of men. The ones that come to mind are Grant @ Cold Harbour, Sherman @ Kennesaw Mountain, John B Hood @ Franklin , Lee @ Gettysburg Pickett's Charge. For me they are all bad but Franklin was the worst.
War isn't just about things change going right it also about things going wrong. No army in history wins every single battle sometimes stupid mistakes are made or things don't go according to plan.
The biggest blunder the Confederacy made was not listening to either San Huston the Governor of Texas or William Sherman when he was an instructor at a military school in Louisiana just prior to the ACW. Bot men accurately predicted how a Civil War would play out .