I believe if Lincoln would have not pulled out the stops and violated Constutional Law and International Laws I don't think he would have had the success he had. His troops violated morality and God's Laws all in the name of the Union.
I know there are those who applaud the rape, theft and arson of the Southerners and their homes. When you attack a man's family you turn his attention from the front to home. Did the South fail in their attempt to free themselves ? Yes. Was it because they couldn't achieve their goal by fighting a War by the rules of the day? No. It was because the adversary allowed his soldiers to commit crimes against humanity and decency.
It's hard to win a fight when you are required to wear boxing gloves and your opponent is using a baseball bat,,,