Vritrasura was a very powerful Asura who almost killed Indra in a battle. He is also depicted as a serpent or dragon. His mother’s name was Danu, who was the mother of Danavas. The word Vritra (वृत्र) means “the enveloper”. The slaying of Vritrasura is considered the biggest achievement of Indra.
The Story of Vritrasura in the Rig Veda (Mandala 1, Hymn 32):
Vritrasura had kept the waters of the world captive. Therefore, Indra planned a battle against him. Before going to war, he drank a large volume of Soma at Tvashtri’s house, who is an artisan god. Tvashtri designed the thunderbolt for Indra. Then, Indra requested Vishnu to create space for the war. Lord Vishnu did this by taking three strides and hence called Trivikrama.
In the fierce battle, Vritrasura broke the two jaws of Indra, but then Indra threw him down crushing the 99 fortresses of Vritra. Thus, Indra got the name Vritrahn (the Slayer of Vritra).
In the Rig Veda, Vritra is referred to as a serpent and a dragon also.
The Story of Vritra in the Bhagavata Purana (canto 6, Chapter 9-17):
The story in the Rig Veda is elaborated in the Puranas like many other stories in Hinduism. In the Rig Veda, Indra is addressed like a hero in one of the hymns for slaying Vritrasura, but in the Puranas, he is depicted as a god who uses unfair means to save his throne.
The Previous Birth of Vritrasura:
In his last birth, he was emperor Chitraketu. He had 10 million wives but was childless. So he prayed to the sage Angiras. By the grace of the sage one of his queens, Kritadyuti, gave birth to a son, but the son was murdered by other queens out of jealousy. The sage Angiras and Narada brought the infant back to life again.
They also taught theosophy to Chitraketu. He sat in contemplation for eight days and then changed himself to a Gandharva. While he was flying, he saw the goddess Parvati sitting on the thigh of Lord Shiva and laughed aloud. The angry goddess cursed him to become an Asura.
Therefore, Chitraketu was born as Vritrasura in his next birth.
Background of the Birth of Vritrasura:
Sage Vishwarupa, who was serving as a priest to gods, had three heads. Both the gods and the Asuras were his relatives. While offering clarified butter in the sacrificial fire of yajna in names of gods, he also offered oblations to demons secretly. When Indra came to know about this, he got furious and cut the three heads of Vishwarupa.
Knowing this, Vishwarupa’s father, Tvasta, vowed to kill Indra to avenge the murder of his son.
Birth of Vritrasura:
Tvasta performed a yajna. He offered oblations in the sacrificial fire, saying, “O enemy of Indra, flourish to kill your enemy without delay.”
Thereafter, from the southern side of the sacrificial fire, known as Anvāhārya, came a fearful personality who looked like the destroyer of the entire creation at the end of the millennium.
The body of the demon grew day by day. Soon he covered all planetary systems. Therefore, he was named Vritra, one who covers everything.
Lord Vishnu’s Advice to Gods:
All the gods under the leadership of Indra attacked him with their weapons, but Vritrasura swallowed all their weapons. The fearful gods then ran away and went to the refuge of Lord Vishnu. They eulogized him. Lord Vishnu pleased with their eulogies, advised Indra to approach Sage Dadhichi. Because of the austerity and the Narayana Kavacha, his body was very strong. Therefore, only a weapon made from his bones was useful to kill Vritrasura.
The Death of Vritrasura:
Accepting the request of gods, Dadhichi gave up his body for the great cause, and his soul left this world. With the help of Vishwakarma, gods prepared Vajra from Dadhichi’s bones.
Armed with Vajra, Indra and gods attacked Vritrasura and other Asuras. This war took place at the end of the Satya-Yuga and the beginning of the Treta-Yuga.
Although one of his arms was severed from his body, Vṛtrāsura angrily approached King Indra and struck him on the jaw with an iron mace. He also struck the elephant that carried Indra. Thus, Indra dropped the Vajra from his hand, but Vritrasura let him take his Vajra again and fight. After this, Indra cut the remaining hand of Vritrasura. But the demon did not give up. He assumed a gigantic form and swallowed Indra along with Airavata.
With the Vajra, King Indra, pierced through Vritrasura’s abdomen and came out. He then immediately cut off Vritrasura’s head, which was as high as the peak of a mountain.
Although the Vajra revolved around the demon’s neck with great speed, separating his head from his body took one complete year – 360 days, the time in which the sun, moon, and other luminaries complete a northern and southern journey. Then, at the suitable time for Vritrasura to be killed, his head fell to the ground.
After his death, a living spark then came forth from his body and returned home, back to Godhead. He entered the transcendental world to become an associate of Lord Sankarshana.