Ego. Most successful generals have a darned good opinion of themselves or they would not be successful generals. I guess it would be where the ego trips them up? Well, there's Joe Hooker. Might not have been a top drawer general but he was effective...but then he started pulling Lincoln's beard. Lincoln could put up with that if Hooker got him a victory, but instead got him a resounding defeat at Chancellorsville. Got the toe of Lincoln's boot on his posterior! There's John Pope, who boldly declared his headquarters would now be in the saddle...which prompted stone-faced Stonewall Jackson to wisecrack Pope didn't know his headquarters from his hindquarters. Pope produced resounding defeat, got the toe of Lincoln's boot so hard he was kicked clear to Wisconsin to give Indians a bad time. Beauregard was arrogant enough to take a leave after a critical battle - Shiloh - and he really did need it. But he probably should have told his commander in chief about it! The resultant dispute with said commander in chief caused Beauregard to dip his pen in poison and write many letters. With the Southerners it seemed to be more pride than ego - Joe Johnston's first snit was about Lee being ranked ahead of him, never mind he was one of the four top generals of the Confederacy.