Chitrangada
Chitrangada was the elder son of Shantanu and Satyavati. Since his elder half brother Bhishma (son of Shantanu and Ganga) took a vow of not ascending the throne of Hastinapura, he became the king after Shantanu and was very successful. He had no problem. He had an uneventful life. He was slightly arrogant and proud. He was a great warrior. He was undefeated King – defeated many Kings during his short rein.
Chitrangada was powerfull warrior and great king who succeeded in wining digvijay yatra ( a short version of ashwamedh were kings win neighboring and far off kingdoms to win supremacy trading of taxes in percentages in return fro friendship) Chitrangada gains fame harming the reputation of great gandharva named Chitrangada .
There should be no 2 persons with same name having equal caliber in all fields to exists on this earth so Gandharva challenges a valliant Kshatriya for the battle , so only one needs to come out alive to live peacefully . Gandharvas didn’t challenge Hastinapur kingdom to prove supremacy to let Bhisma take part in the war and wipe out entire Gandharva clans from face of Earth . It was one to one battle, a Kshatriya has only option to accept challenge and fight , no supreme powers can change that law or Kshatriya looses his reputation and needs to take sanyas.
Death for Kshatriya in battlefield was most respected death and it opened doors to heavens so fearing death was unacceptable to Kshatriya , Kshtiya families accepted the same and took it for granted if they loose there loved ones in battle field.
Chitrangada and Gandharva with the same name fought with each other for three years outside Hastinapur. The war happened at the banks of River Saraswati. Ultimately after three years, Gandharva emerged as the winner and he killed Chitrangada in the battle. Chitrangada died childlessly, so the throne of Hastinapur went into hands of Vichitravirya.
During this war Bheeshma was away helping Lord Indra in a mission . So he was not able to save Chitrangada .
Unlike Vichitravirya, Chitrangada was really a worthy son and well suited to be the King of Hastinapur.
Vichitravirya
After Chitrangada’s death, his young brother Vichitravirya was crowned as a king, while Bhishma ruled on his behalf until Vichitravirya grew up.
Vichitraveerya had some health issues right from childhood. He was not very healthy. Besides, with the death of his brother and passing of his father, he was pampered much by Satyavati. For some reasons, The King of Kashi did not invite Hastinapur kingdom for the swayamvar of his three daughters. Also, I heard that at that time, Vichitraveerya was not fit enough to get a bride for himself using his abilities. So, Bhishma had to abduct the princesses for his marriage.
Vichitravirya died few years (or a few days) after his wedding with Princesses Ambika and Ambalika. He died without a progeny.
With no heir to the throne, Satyavati requested Bhishma to marry the widows of Vichitravirya following the practice of Niyoga and rule as king. Bhishma refused, reminding Satyavati of the promise he made to her father and his vow of bachelorhood.
Satyavati knew that this was the time to call her son Vyasa to aid her. Satyavati coaxed Vyasa to have Niyoga with his Vichitravirya’s widow for the perpetuation of the dynasty, for the sake of this Bhishma’s pledge, for kindness to all the creatures, and for the protection of the people. Finally, Satyavati managed to convinced Sage Vyasa. With great difficulty, she obtained the consent of her “virtuous” daughters-in-law. Vyasa finally agreed for this “disgusting task.” He warned Satyawati that the offspring of perversity cannot be a source of joy.
Sage Vyasa had a fierce personality and a bright, glowing spiritual aura around him. Hence upon seeing him, Ambika who was rather scared shut her eyes, resulting in their child, Dhritarashtra, being born blind but strong. Satyavati considered such heir to be an unworthy king. Hence, she asked Vyasa to have Niyoga with Ambalika, her second daughter-in-law. During their Niyoga, Ambalika fell pale due to Vyasa’s grim appearance. As a result, a pallid child was born. Ambika gave birth to blind Dhritarashtra whereas Ambalika gave birth to the pale Pandu.
Alarmed, Satyavati requested that Vyasa meet Ambika again and grant her another son. Ambika instead sent her maid to meet Vyasa. The duty-bound maid was calm and composed; she had a healthy child who was later named Vidura.