One day Raajaa Shantanu went for gaming spree. Following a game he came out towards Gangaa River, that he smelled a sweet divine scent. He followed the scent and found a beautiful girl rowing a boat in the river. She was very beautiful so just to see her for longer time he sat in her boat and crossed the river several times. Now this was his daily affair. That girl was the daughter of Daashraaj and her name was Satyavatee. She got this sweet smell by the Vardaan of Maharshi Paraashar (Ved Vyaas Jee's father)

Raajaa liked her so much that he went to the girl's house with the proposal of his marriage to her. But Daashraaj said - "Mahaaraaj, This is my good luck that you have proposed for her, but astrologers say that her children will rule the kingdom. You have already declared your eldest son Devavrat as Crown Prince, then how her children will rule the kingdom?" Raajaa thought and thought but couldn't find any solution for this. He could not have injustice with his eldest able son. So he became worried about this. Neither he could dethrone his son, nor he was able to marry Satyavatee. He got sick.

One day his son Devavrat noticed that his father was not well for some time. He got worried about him. He asked him - "What is that is worrying you, father?" Raajaa said, "Nothing, my son." But Devavrat didn't get convinced with his answer. 

So he asked his ministers and came to know the whole story. He found out about the girl and went to her house with the proposal of his father's marriage to Satyavatee. Daashraaj said the same thing to Devavrat also - "He did not promise that Satyavatee's child will rule the kingdom. That is why this marriage cannot be solemnized". Devavrat said - "In fact you asked the wrong person. He had no right to dethrone me, because he has already given me the throne. But I can dethrone myself. I vow that I leave this status now, and I will not claim the throne in future also."

Daashraaj said - "This is all right, but as your father could not promise on your behalf, you also do not have any right on behalf of your children too. if your children asked their rights of throne, and fought with Satyavatee's children, then?" Devavrat said - "For that I vow that I will never marry and will remain lifelong Brahmchaaree. I will live without children and die without children. Any problem now?" Daashraaj Said - "No prince. Now I will happily marry my daughter to Raajaa Shantanu. You are blessed. Only a son like you could take such a vow  for his father's pleasure." Devtaa also showered flowers on Devavrat and Aakaashvaanee said - "Who else can take such a Bheeshm (difficult) vow except you? From today you will be known as Bheeshm in Trilok." Since then he is known as Bheeshm only, not many people know his real name.

When Shantanu heard about this he got extremely sad. But pleased with his son, he also gave him Vardaan of Ichchhaa Mrityu (he will die only when he will want). Daashraaj married his daughter Satyavatee to Shantanu. Both had two sons in the course of time - Chitraangad and Vichitraveerya. Shantanu died in their young age, so Bheeshm took care of those children.