At the end of the Kurukshetra war, most of the Kuru warriors were killed. Asvatthama, the son of Guru Dronacharya, was one of those who survived. He was furious at the destruction of the Kauravas and personally hurt that his father had been killed by the Pandavas using trickery. To exact revenge, he attacked the Pandava camp at night. The war was already over, but even if it were on, attacking a sleeping enemy at night was clearly against the rules. With the advantage of surprise, Asvatthama easily rampaged around the Pandava camp and killed five warriors sleeping in a tent. He assumed that they were the five Pandavas. In fact, they were the five Upa-pandavas—sons of Draupadi.
Knowing that his act was despicable, Asvatthama ran away in his chariot. Draupadi was inconsolable. Arjuna promised to bring her Asvatthama’s head. Arjuna, with Sri Krishna as his charioteer, pursued Asvatthama. Asvatthama tried to escape, but his horses became fatigued, and he saw that he was cornered. To save his life, he used the divine Brahmashira weapon, the knowledge of which had been given to him by his father. He did this despite knowing that he only knew to launch the weapon and not withdraw it.
Sri Krishna told Arjuna that it could be countered only by the Brahmashira weapon itself. Arjuna used the Brahmashira weapon, too. The two opposing weapons threatened to burn down the entire world. For everyone’s well-being, the rishis arrived there and asked both the archers to withdraw their weapons. While Arjuna did so, Asvatthama replied that he did not know. The rishis severely criticised Asvatthama, who then directed the weapon to destroy the unborn son of Abhimanyu—Arjuna’s son who had been deceitfully killed by the Kauravas.
When Asvatthama was brought before Draupadi, she spared his life because he was the son of their guru and, therefore, like a guru himself. Also, his mother Kripi was still living, and Draupadi did not want her to grieve like herself. Even after this pardon by Draupadi, Sri Krishna did not want to let Asvatthama go unpunished because his crime was too heinous. While conflicts are a part of life, there is some morality even in conflicts. One is free to oppose those with whom one has disagreements, but to channel one’s anger on someone who is not directly a part of the conflict is unacceptable. Abhimanyu’s son was not even born and thus entirely blameless and defenceless. To punish Asvatthama for his attack on such a defenceless being, Sri Krishna cursed him to wander in desolation forever, emitting a foul smell and detested by all beings. Thus, Asvatthama was cursed to a fate worse than death.