The doctrine was in effect - take from the land enough supplies to sustain the army but do not assault the citizens or enter their homes, unless partisans (like the french resistance in ww2) present themselves then basically torch the whole place. I don't think the intention was to decimate the Souths economy as hard as they did, rather to try and bring an end to the war asap. Sounds fairly standard as far as war time doctrines go but the actual implementation of it leaves a lot to be desired. The south did not recover for a very long time.