Before any violence, Alice shares with Aro her vision of the battle that is to come, during which both sides sustain heavy casualties, including Aro himself. Aro believes her, giving Alice and Jasper an opportunity to reveal their witness (which is a half mortal half vampire just like Renesmee). The witness proves that he is mature, supporting the notion that Renesmee is not a threat. The Volturi leave without a fight.