Didn't Lee give up to Grant? Kind of seems silly to say he was a poor General in light of the fact that he won. I am sure you can find tactical mistakes, but operationally he was in charge at the end of the day.
So the Union finally after holding superior strength for 4 years of the war - gave Grant command - and finally captured the enemy Capital only 150 miles from Washington.
Grant was at most competent - amoung other totally incompetent Generals.
Hackworth should have used Lee for his example - but I will forgive him.