By the eighteenth day the great Kaurava army was all but gone. The mighty commanders had fallen one by one — Bhishma, then Drona, then Karna, struck down by Arjuna in the war's most sorrowful duel, the secret brother killed by his own. At last only Duryodhana remained of the hundred sons of Dhritarashtra, his cause in ruins. He fled and hid beneath the waters of a lake, but the Pandavas tracked him there and goaded him out to face them.

He chose to meet Bhima in single combat with the mace, the weapon both had mastered. It was a furious, even fight, and Duryodhana had the better technique. But a vow hung over the duel. Years before, in the hall of the dice game, Duryodhana had bared and slapped his thigh in insult before Draupadi, and Bhima had sworn to shatter that very thigh. Striking below the waist was against the rules of mace-combat, and so the blow was unlawful — a stain the epic does not hide. Yet, prompted by a sign from Krishna, Bhima struck Duryodhana's thighs and broke him. The proud prince fell, and lay dying, bitterly defending his own life and accusing his enemies of every foul stroke that had won the war.

His complaint was not empty, for the victory had been bought with deceptions, and the worst was still to come. That night, the war already decided, three Kaurava survivors crept toward the sleeping Pandava camp. Chief among them was Ashwatthama, son of the slain teacher Drona, mad with grief and fury. This is the Sauptika Parva, the "book of the sleeping" — and it records an atrocity. By night, against every law of war that forbids killing the sleeping, the unarmed, and the unprepared, Ashwatthama fell upon the camp and slaughtered the warriors in their beds, among them the five young sons of Draupadi and the prince Dhrishtadyumna. The Pandavas survived only because they happened to be absent.

So the war ended not in clean triumph but in horror. Duryodhana, dying, is said to have laughed that his enemies' victory was now as soiled as his defeat. The dreadful weapon Ashwatthama loosed in the aftermath, and Krishna's intervention to blunt it, only deepened the sense that something sacred had been broken. The Pandavas had won the field. But the night raid hollowed out the winning, and the survivors woke to ashes where their children had slept.