IS grew out of the vacuum of a civil war in Syria and is predicated on creating a Caliphate. They cannot physically grow if they are not able to gain ground. Their recruitment message is likely to be significantly weakened if they lose territory and battles. Unlike AQ or even the Taliban of recent years they are not able to avoid pitched battles, they can&#x27;t melt into the background - they would have to stand and fight for their territory - thus they can be defeated.