The king of the Panchalas, Drupada undertakes a putrakami yagna, a sacrifice to please the Gods and obtain offspring by their blessing. Drupada desires a son who can kill Drona, the Kuru martial guru who had humiliated him in battle and taken half his kingdom, even though it was Drupada who had reneged a promise made to his childhood friend Drona, that he would share his kingdom with him.
With the help of two brahmins, Drupada undertakes the sacrifice. After his wife takes the sacrificial offerings, out of the fire a fully grown powerful young and armed man before their very eyes. He is already bestowed with great martial and religious knowledge.
Even though he is the prophesied killer of Drona, he is accepted by Drona to join his school for young princes, where he learns the advanced military arts.
When his sister is bethrothed to a young brahmin of five, who wins the martial contest at her swayamvara, Dhristadyumna secretly follows the five brahmins and his sister, only to discover that they are in fact the five Pandavas: Yudhisthira, Bhima, Arjuna, Nakula and Sahadeva.
Taking the advice of Lord Krishna and Arjuna, Dhristadyumna is installed as the Commander in Chief of the Pandava Army.
At a point when Drona, as the Kuru commander is killing vast numbers of Pandava troops, Krishna advises Yudhisthira to adopt a plan to kill the preceptor now. As it is known that as long as Drona has raised his weapons he is invincible to all other warriors, Krishna advises that it be proclaimed that Drona's son, Ashwathama has just died in the battle. It is known that out of the grief of such an eventuality, Drona will at least temporarily drop his arms.
Krishna justifies this lie to Yudhisthira as necessary to the victory of morality in the war. As Yudhisthira continues to hesitate, his brother Bhima kills a known elephant in the Kuru legions named Ashwathama and celebrates shouting "Ashwathama is dead! Ashwathama is dead!".
Shocked with disbelief when the news reaches him, Drona seeks out Yudhisthira to ascertain the news, knowing that the son of Dharma would never speak a lie. Yudhisthira tells him that Ashwathama is dead, but mutters "(I wonder) whether the man or the elephant...." ( Aswathama Hatah... naro waa Kunjarovaa)in an inaudible voice to prevent telling a whole lie or as another version tells us that he said it equally loud but Shri Krishna had planned to blow his conch at that exact moment so that Drona is unable to hear that part.
Now convinced, Drona lays down his arms and sits in meditation. It is actually said in the epic that Drona's soul has already left his body through his mediation, but Dhristadyumna takes this opportunity, swings onto Drona's chariot, and lops off his head.
Dhristadyumna is verbally abused by Satyaki and Arjuna, who were devoted students of Drona, but is defended by Krishna.
After the war is over, Ashwathama treacherously attacks the Pandava camp during the night, killing Dhristadyumna and the sons of Draupadi in revenge for his father's death and the defeat of the Kurus.