Shantanu was horrified from the scene he saw in front of his eyes he thought to himself that how could a mother do like this to her own child, he wanted to save his son and ask his wife why did she do such an horrendous act, but he remembered the promise he made to her and out of helplessness kept his mouth shut.
After one year when Shantanu almost forgot the trauma of losing his first child his wife gave birth to a second son and this time too she took the baby to the river and drowned it Shantanu was shocked that why is she doing this again but he could not ask even a single question.
Like this the queen gave birth to a total of seven sons but she dropped all her son into the depths of the river Shantanu who was watching was in agony and extreme pain no one could imagine how much pain he was going through by loosing his children and also the helplessness of not being able to ask his wife the reason she is doing these horrible deeds.
After a year the eighth child was born the queen was about to do the same thing by drowning the baby into the river but Shantanu who was watching this could not tolerate this anymore and yelled.
"Stop!!! stop this at once i won't let you do the same thing to this child I don't care about that promise anymore I can't tolerate seeing my children die in front of my eyes anymore."
As Shantanu yells at the queen the queen replies
"Well now you have broken your promise so I can't stay beside you anymore. Now I am going to leave at once but before I leave I will tell you the reason as to why i have been doing this. I am the river goddess Ganga and these eight children of ours are the eight Vasus of the Haven. They were provoked by their wives and tried to steal Vasishta's cow Kamadhenu Vasishta who saw this cursed the Vasus to live a human life and experience the pain and difficulties of living as a human. The Vasus were very scared and begged for Vasishta's forgiveness but Prabhasa the eighth Vasu who was the one that stole the cow didn't ask for any forgiveness and stood ideally so, Vasishta could not take back his curse said the seven Vasus who begged for Vasishta will be short-lived.
I was assigned to be their mother and I had drowned them to release them from their curse, and Prabhasa who did not ask for mercy would live a long life on this earth and your eighth son is the eighth Vasu Prabhasa.
Shantanu was bewildered and shocked by this.
Shantanu pleaded with Ganga to not live by his side as he could not live without her also it should be hard for a boy to live without his mother.
Then Ganga replied
"Ok I will take this child with me and train him to be a worthy son and an exceptional warrior and return him when he becomes an adult"
Ganga then disappeared with her son into the river. Shantanu was heartbroken he would come everyday to the river banks. Many days passed, days turned months and months turned to years but there was no sign of Ganga and his son.
One day the Rakshas(demons) started attacking the city of Hastinapur and Shantanu marched his entire army to kill the Rakshasas by the time Shantanu arrived there was a young adult who had the eyes of a worrier and face so beautiful that could shun even the gods he single handedly killed all the Rakshasas.
Shantanu was astonished, he got down from his chariot and came to ask the young man for his identity.
The young man came towards Shantanu, he bowed and touched his feet for his blessings.
Shantanu asks"Hey boy why are you touching my feet you don't even know who I am."
To this the man replied
"How could I not touch my own father's feet?"
Shantanu was shocked and it took some time for him to digest the information. As he was still shocked Ganga appeared from the water.
"Oh lord he is your son, he has mastered the arts of warfare from his guru(teacher) Parashurama (Vishnu's Avatar) and he is as skilled as his guru. His name is Devabrhata. Now I've come to return your son to you." Said Ganga and she vanished into the river.
Shantanu was overjoyed upon seeing his son Devabrhata and immediately took him to the palace of Hastinapura.He was good at everything from studies to warfare.There was no one who could win against him in anything. Soon he became the most popular prince. He was kind to his subjects and was also very courageous it was the obvious choice that he was the rightful heir to the throne of Hastinapur.
The impressed Shantanu declared Devabrhata as the crown prince in front of his courtiers.
Shantanu who was extremely happy to have Devabrhata by his side felt lonely at times. He would every day come near the banks of the river and think of Ganga and sadly walked near the banks. That had become his daily routine, but one day one he came down to the river who smelled a beautiful scent of flower, it felt coming from near but at the same time it felt like it was out of his reach.
Shantanu searched all over the rever banks and then he came across a beautiful woman the scent was emitting from her body. Shantanu yet again fell in love at first sight with this woman. The thoughts of Ganga vanished from his mind as if it was never there and filled with woman he just met. The only thought that came across his mind was that this woman was his destiny and he should not loose her no matter what may happen.