When the period of exile was completed, Duryodhana refused to return Yudhishthira’s kingdom. Yudhishthira made numerous diplomatic efforts to retrieve his kingdom peacefully but in vain. He was convinced by Krishna to wage war. The flag of Yudhishthira’s chariot bore the image of a golden moon with planets around it. Two large and beautiful kettle-drums, called Nanda and Upananda, were tied to it. Yudhishthira had to bend numerous rules of Dharma during the course of the war. Krishna made him trick Drona about the news of the death of Ashwathama. Yudhishthira also had to slay a number of warriors, including his own uncle, Shalya.