- On the previous day, Duryodhana was quickly losing faith with his uncle. He began to suspect that Bhisma was throwing the contest in favor of the Pandavas. Karna didn't help any when he offered to take charge in place of the old man. So Duryodhana asked the old man to either fulfill his oaths or get out of the game. Now today, on the 9th day, Bhisma sets out to finish off his Dharma so he could move on to the next phase in his life.
On the battlefield, he kills hundreds of thousands, including the entire nation of the Saumakas. Bhisma takes out a large chunk of the Pandava army. If he keeps this up another day or two, there will be no one left to fight on the Pandavas' side.
So that night, after the battle, they go unarmed to Bhisma's tent and ask him
what they should do about this and how they should win the war. Of course, they've known what they needed to do all along, but it's nice to have Bhisma tell you himself and to even give his blessing! We'll see tomorrow if Arjun finally carries through with his duty...