@xbrunnox but he was brought the lord to negotiate so he could destory all the leader and then stop the messagers then repeat a couple of times most lords would decide that life is better than death and hostages might work but the thing is once to kill them or hurt them there is no reason to negotiate or show mercy
not to mention this is the goddess kingdom and she wants him to not wipe it out so I imagine that she would ask them to surrender
but then it would be a very different manga but still feel that he choose a super weak negotiating position to start from considering could make them give up half now and then half on him delievering his end