01The terrible vow
Ganga gave her eighth son back to Shantanu grown: he had learned the Vedas from Vasishtha and the science of arms from Parashurama, and Shantanu made him crown prince. Four years later the king fell in love with Satyavati, and her father asked that her son should rule. Devavrata went to the fisher-chief himself. He gave up the throne, and when the chief still feared his sons, he swore never to marry. The devas and rishis showered flowers and cried out “Bhishma”, the one of the terrible vow. Shantanu, moved, gave him the boon of dying only when he chose.
02Amba and Parashurama
For his half-brother Vichitravirya, Bhishma carried off the three daughters of the king of Kashi from their svayamvara. The eldest, Amba, told him she had already given her heart to Shalva, king of Saubha, and he let her go. Shalva would not take her back. She went to Parashurama, and the guru came to make his pupil marry her. Bhishma refused, and teacher and pupil fought at Kurukshetra for twenty-three days until the devas and Bhishma’s ancestors stopped them. Amba turned to tapas, swearing to bring about his death, and was born again as Shikhandi.
03Ten days in command
Bhishma led the Kaurava army knowing which side dharma was on. He would not kill the sons of Pandu, he told Duryodhana, but he would cut down ten thousand warriors a day, and he did. On the ninth night Yudhishthira came to his tent and asked how he could be defeated. Bhishma told him: put Shikhandi in front, for he would not raise his bow against one born a woman. On the tenth day Arjuna shot from behind Shikhandi, and Bhishma fell with so many arrows in him that his body did not touch the ground. Arjuna made him a pillow of three arrows and drew water from the earth with a shaft for him to drink.
04Teaching from the arrows
He lay there through the rest of the war and after it, waiting for the sun to turn north. Krishna brought Yudhishthira to him, and Bhishma, his pain lifted by Krishna’s grace, taught the new king through the long Shanti and Anushasana Parvas: the duties of a king, dharma in times of distress, the path to moksha, and the thousand names of Vishnu. When Uttarayana came in the month of Magha, he gave up his life by yoga, and his breath rose out through the crown of his head. Magha Shukla Ashtami is kept as Bhishma Ashtami, and many offer him tarpana that day.
Famous verses
अद्य प्रभृति मे दाश ब्रह्मचर्यं भविष्यति । अपुत्रस्यापि मे लोका भविष्यन्त्यक्षया दिवि ॥
From this day, fisherman, I shall live as a brahmachari. Even without a son, the undying worlds of heaven will be mine.Mahabharata 1.94.88 (BORI CE), Devavrata to the fisher-chief