Santanu, the king of Hastinapur married a beautiful girl named Ganga, who was river of Goddess in disguise. She had agreed to marry him on the condition that he had to never question her actions. Over the years they had seven children but Ganga had thrown them into the river. Santanu was distressed but he did not question her so as to keep his promise.
Finally eight children were born then he questioned her who she really was and why she was doing this? Then Ganga revealed herself and told him that her children were cursed to be humans so she had to end their punishment by drowning them into river. She left Santanu along with her eight child named as Devratna Santanu had not kept his promise.
Devratna is later better known by name called Bhisma which means doer of difficult deeds. He received this name after promising that he will never marry or have children. He has taken this vow in order of honoring his father wish of marrying Satyavati.
She agreed to marry on the condition that she would be the mother of king. So Bhisma had taken such a difficult vow. Over the years santanu had died and half-brothers of Bhisma were died in the battle and the others became old enough to marry. So Bhisma abducts three sisters and on returning to home he comes to know that one of the sisters called Amba has already chosen suitor so he allows her to leave. But her suitor does not want her any more so Amba returns to Bhisma and asks him to marry. But Bhisma refuses to marry her so as to keep his vow taken in honoring his father’s wishes. She takes a vow that she would one day kill him.
The importance of vows and promises are seen throughout the epic. A vow will become truth and must be fulfilled no matter whatever happens. Even lives are sacrificed in keeping their words and promises.
There are no men left besides Bhisma but he had renounced women. So Satyavati decide to ask her first born son Vyasa, the poet to give sons to the two princesses. He goes to them but they dislike him because he has taken a vow of poverty and he is not clean and smells. He explains them that they will bear sons but unfortunately the first son will be blind because the first princess closed her eyes on seeing Vyasa.
The second son is pale because the second princess became pale at his touch. The blind one is called Dritarashtra and the pale one is named as Pandu. Vyasa had also a third son named vidura by a handmaiden. As Dritarashtra was blind he was unfit for becoming king. Vidura is also ruled out because he is from a lower caste. So Pandu becomes the king of Hastinapura.
One day Pandu accidentally shoots a gazelle while hunting in the forest. That gazelle is a Brahmin in disguise who curses him that he will die instantly, if he makes loves with either of his wives Kunti and Madri. Knowing that he can never have children he resigns from throne and moves into forests along with his wives.
Kunti informs Pandu that she has a magic power of getting sons descended directly from Gods. By mantras power she can invoke God at will and have son by him. She had three sons, first son Yudhishthira son of God Dharma, second one Bhima, the strongest of men son of wind God, Arjuna an irresistible warrior, the son of Indra.
Madri also uses the mantra and gives birth to twins Nakula and SahaDev. These five sons of Pandu are called as Pandavas and considered as heroes of Mahabharata. Pandu surrender his passion for Madri though she tries to push him back he dies instantly as by curse. So she joins him in the funeral pyre. Meanwhile Dritarashtra rules the kingdom and marries Gandhari.
When she learns that her husband is blind she takes a vow that she will join her husband in the world of darkness by covering her eyes with a blindfold. After few years and an abnormal long pregnancy Gandhari give birth to one hundred sons called Kauravas. The first born son is called Duryodhana. Vidrua says that his first brings hate and destruction into the world. He will one day cause the destruction of their race. Vidura urges the king to get rid of Duryodhana but he ignores him.
Through out the epic it is seen that there are vows taken and trying to keep the promises no matter ever happens. But by the end it is also seen that every vow taken results in good for someone or protecting justice, truth, Dharma.
In this story when Bishma allows Amba to go to the one that she loved it can be seen that he respects her wish of making choice of the person with whom she has to live for her rest of the life just like now a days. We can also observe revenge, consequences of mistakes and one will definitely have to face the consequences as a result of their actions at sometime.
We can also see that parents love their children and take care no matter whatever happens like when vidhura warned Dritarashtra about his first son that will be a threat to race.