Subhadra was Shri Krishna's sister. She was married to Arjuna. Abhimanyu was their son. At the time of the war of Mahabharata took place, Abhimanyu was a brave and adventurous young lad, as brave and adventurous as Arjuna.
On the thirteenth day of the war, Dronacharya formed the Chakravyuha. This was a cause of worry toYudhishthira as only two people knew how to break through the Chakravyuha. One was Arjuna and the other, his son Abhimanyu.
Arjuna was away, fighting against the Trigartas to the south of Kurukshetra. "What should we do now?" thought Yudhishthira.
"Arjuna is not here and if I do not send Abhimanyu to break through the Chakravyuha, we are sure to lose this war." But Yudhishthira did not have the heart to put Abhimanyu's life in danger by sending him to break through the Chakravyuha.
