Lord Parashurama was enraged upon discovering his disciple’s transgression and resolved to punish him. He challenged Bhishma to a battle and attacked him ferociously. Out of respect for his guru, Bhishma initially defended himself without retaliating. Parashurama, frustrated, taunted him, "Do you truly believe you could defeat your guru if you fought with all your strength? Your arrogance astounds me!"
Eventually, Bhishma and Parashurama engaged in a fierce, hand-to-hand duel that lasted twenty-three days, with neither emerging victorious. Parashurama then apologized to Amba for his failure to defeat Bhishma. Undeterred, Amba prayed to Lord Shiva, determined to be the cause of Bhishma’s death. After years of severe penance, Lord Shiva appeared before her and granted her wish, declaring, "In your next life, you will be the cause of Bhishma's demise."
Impatient to fulfill her goal, Amba ended her own life, and in her next birth, she was born as Shikhandi, the daughter of King Drupada.
Meanwhile, King Vichitravirya had married Ambika and Ambalika, both of whom were delighted to wed the valiant and handsome king. Tragically, Vichitraveerya soon succumbed to a fatal illness, leaving both queens childless widows. Bhishma took responsibility for the queens and the kingdom, but the Kuru dynasty still faced the crisis of having no heir.
True to his vow, Bhishma refused to ascend the throne. Queen Satyavati, heartbroken by the loss of her sons, mustered the strength to lead for the sake of the Kuru lineage. She often blamed her father's actions for the tragic fate that had befallen Bhishma. Summoning him, she said, "As Shantanu’s son, it is your duty to prevent the extinction of the Kuru clan."
"What would you have me do?" Bhishma asked.
"Fulfill the family line by accepting your brothers' widows," Satyavati implored.
"That is out of the question, as everyone knows my reasons," Bhishma replied. "However, a widow can continue the lineage by marrying a male member of the same clan, provided he is of noble status."
Satyavati then recalled her son, Maharshi Vyasa. "Yes, I have a son, born before my marriage, through Sage Parashar’s blessing."
"Please invite him to the palace without delay," Bhishma advised.