Age of characters?

TBirthT
The legend behind Bhishma's birth is as follows " once the eightT HTTUVasusUTHT T("Ashtavasus") visitedHTUVashishtaUTH's ashram accompanied by their wives. One of the wives took a fancy toT HTTUNandiniUTH, Vashishta's wish-bearing cow and asked her husband Prabhasa to steal it from Vashishta. Prabhasa then stole the cow with the help of the others who were all consequently cursed by Vashishta to be born in the world of men. Upon the Vasus appealing to Vashishta's mercy, the seven Vasus who had assisted in stealing Nandini had their curse mitigated such that they would be liberated from their human birth as soon as they were born; however, Prabhasa being protagonist of the theft, was cursed to endure a longer life on the earth. The curse, however is softened to the extent that he would be one of the most illustrious men of his time. It was this Prabhasa who took birth as Devavratha (Bhishma).
TEarly lifeT
Bhishma was born as the youngest son of the illustrious KingT HTTUShantanuUTHT TandT HTTUGangaUTH. As per the Mahabharata, Shantanu saw Ganga on the banks ofT HTTURiver GangaUTHT Tand enamored by her beauty, asked her to marry him. She agreed but with the condition that Shantanu would never question her, no matter what her actions " if he ever broke his promise, she would leave him, never to be a part of his life again. Shantanu readily agreed to this seemingly harmless condition and was thus married to Ganga. Eight children were born to this union, the eighth of which was Bhishma himself. The seven siblings born before him were drowned by their mother Ganga in order to break their curse " as they were incarnations of the aforementioned Vasus, who do not like to live the life of Humans. Shantanu silently bore the torture of watching his wife drown his offspring seven times. However, when Ganga was about to drown Bhishma, Shantanu could no longer contain his anguish and burst into protest. Ganga, aware of the eighth child's destiny to live a long life on earth, did not drown the child. However, since Shantanu had broken his promise given to her at marriage, she left Shantanu promising to return the child to him once he is grown up.
During his time with his mother, Bhishma learnt political science fromT HTTUBrihaspatiUTH, the guru of theT HTTUDevasUTH, Vedas and Vedangas from RishiT HTTUVasishtaUTH, and archery fromT HTTUParashuramaUTH, also known as Bhargava, thus becoming an exceptionally skilled administrator. His banner in battle was a golden palm tree.
He was known as 'Bhishma Pitamaha' (TPitamahaTT Tmeaning the grandfather or grandsire) among theT HTTUPandavasUTHT Tand theT HTTUKauravasUTH.
TBhishma's vowT
Bhishma meansT TTHe of the terrible oathT, referring to his vow of life-long celibacy. Originally named Devavratha, he became known as Bhishma after he took theT TTbhishan pratigyaTT T('terrible oath') " the vow of life-long celibacy and of service to whoever sat on the throne of his father (the throne ofT HTTUHastinapurUTH). He took this oath so that his father, Shantanu could marry a fisherwomanT HTTUSatyavatiUTHT T" Satyvati's father had refused to give his daughter's hand to Shantanu on the grounds that his daughter's children would never be rulers as Shantanu already had a son in Devratha. This made Shantanu despondent and upon discovering the reason for his father's despondency, Devratha sought out the girl's father and promised him that he would never stake a claim to the throne, implying that the child born to Shantanu and Satyavati would become the ruler after Shantanu. At this, Satyavati's father retorted that even if Devratha gave up his claim to the throne, his (Devratha's) children would still claim the throne. Devratha then took the terrible vow of life-long celibacy, thus sacrificing his 'crown-prince' title and denying himself the pleasures of intercourse. This gave him immediate recognition among the gods and his father granted him the boon ofT TTSwachhanda MrityuT(control over his own death " he could choose the time of his death, but he was not immortal). Bhishma also took another vow shortly after the marriage of Shantanu and Satayavati. Bhishma vowed he would see his father's image in whoever sat on the throne of Hastinapur and would serve him without question. This vow ended up being the main cause of his problems later on when his nephewT HTTUDhritarashtraUTHT Ttook the throne and wished to make his own son,T HTTUDuryodhanaUTHT Tthe crown prince instead of Dhritarashtra's brotherT HTTUPanduUTH's sonHTUYudhishtiraUTHT Twho was the elder to Duryodhana (and reckoned by all to be the most worthy to become king). As a result Bhishma was forced to comply with all of Dhritarashtra's orders no matter what injustice was done to theT HTTUPandavasUTH.
Bhishma was a great archer and a warrior. In the process of finding a bride for his half-brother the young king Vichitravirya, Bhishma cleverly abducted princessesT HTTUAmbaUTH,T HTTUAmbikaUTHT TandHTUAmbalikaUTHT Tof Kashi (HTUVaranasiUTH) from the assemblage of suitors at theirT HTTUswayamvaraUTH. Salwa, the ruler of Saubala, and Amba (the eldest princess) were in love. Upon reaching Hastinapura, Amba confided in Bhishma that she wished to wed Salwa. Bhishma then sent her back to Salwa who turned her down as it was humiliating for a man to accept a woman who had been so long in the company of another man. She then naturally approached Bhishma for marriage who refused her, citing his oath. Amba, humiliated and enraged beyond measure, vowed to avenge herself against Bhishma even if it meant being reborn over and over again.
Legend has it that at her maternal grandfather's suggestion Amba sought refuge withHTUParasuramaUTHT Twho ordered Bhishma to marry Amba. Bhishma politely refused saying that he was ready to give up his life at the command of his teacher but not the promise that he had made. Upon the refusal, Parasurama called him for a fight at Kurukshetra. At the battlegrounds, while Bhishma was on a chariot, Parasurama was on foot. Bhishma requested Parasurama to also take a chariot and armor so that Bhishma would not have an unfair advantage. Parasurama blessed Bhishma with the power of divine vision and asked him to look again. When Bhishma looked at his guru with the divine eye-sight, he saw the Earth as Parasurama's chariot, the fourT HTTUVedasUTHT Tas the horses, theT HTTUUpanishadsUTHT Tas the reins,T HTTUVayuUTHT T(wind) as the Charioteer and the Vedic goddesses Gayatri, Savitri & Saraswati as the armor. Bhishma got down from the chariot and sought the blessings of Parasurama to protect his dharma, along with the permission to battle against his teacher. Parasurama was pleased and said to Bhishma that if he had not behaved in this manner, Parasurama would have cursed him, for it is the duty of warriors who fight against elders to not abandon the traditions of humility and respect for elders. Parasurama blessed him and advised him to protect his dharma of brahmacharya as Parasurama himself must fight to fulfil his dharma of fighting to uphold his word as given to Amba. They fought for 23 days without conclusion " Parasurama was chiranjeevi (immortal) and Bhishma had a boon that let him choose the time of his death. Two versions exist about how their battle came to and end.
As per one, On the 22nd night, Bhishma prayed to his ancestors to help him end the battle. His ancestors gave him a weapon which was not known to Parasurama. They told him that it would put Parasurama to sleep in the battlefield. A person who sleeps in the battlefield is considered to be dead as per Vedas. They advised Bhishma to call back the weapon at the end of day after sunset so that Parasurama will come back to his sense and that shall bring the end to war. However the weapon was never used as Bhishma walked out of the war.
As per the other version, on the 23rd day, Bhishma summoned the infallible celestial weapon(HTUastraUTH)T TTPrashvapastraT, the method of using which was known to him and him alone. Neither did a counter-attack exist, nor was a defense against it known to Parasurama. As Bhishma mounted the astra on his bow, a divine voice (kshavn) implored Bhishma not to fire the weapon as its use would lead to the humiliation of Bhishma's guru(Parasurama himself). Bhishma refrained from using the weapon that would have brought him certain victory. Upon witnessing this, Parasurama was overcome with adulation for his disciple and proclaimed Bhishma as the victor.
Parasurama thus told Amba that he could not win over Bhishma and gave her the boon of "mahakal shiva". Amba did penance to pleaseT HTTULord ShivaUTH. Shiva gave her the boon that she would be instrumental in the death of Bhishma. Amba would later be reborn as the eunuch princeT HTTUShikhandiUTHT Tin the household of kingT HTTUDrupadaUTH.
TPersonalityT
Bhishma had a stature and personality that in those times were fit for kings. He was a true Kshatriya as well as a disciplined ascetic - a rare combination. He never unnecessarily exhibited the passion and anger that were identified with a Kshatriya. A symbol of truth and duty, the benevolent Bhishma was in all senses a true human.
It is unfortunate that a person as noble as Bhishma saw a life full of loneliness, frustration and grief. But that was how Vashishta's curse was supposed to unfold. Bhishma's human birth was destined to be marked with suffering, and that was how his life transpired right till the last moment; even his death was very painful. But the strong as steel character which he possessed ensured that he never shied away from his duty, and never stopped loving those dear to him.
TSkills, Talents & AchievementsT
Bhishma was not only a good warrior, but also highly skilled in political science. He tried his best to bring reconciliation between Pandavas and Kauravas to prevent the war. Even in the Kurukshetra war while he was the general he tried his best to keep the war low key by minimising confrontation between the two camps. Even as he fell he tried to use the opportunity to persuade both camps to put an end to the war. After the war, while on his deathbed he gave deep and meaningful instructions to Yudhishthira on statesmanship and the duties of a king.
TIn the Mahbhrata WarT
Bhishma is the one who witnessed theT HTTUMahbhrataUTHT Tcompletely from the beginning since the rule ofT HTTUShantanuUTH.
In the great battle atT HTTUKurukshetraUTH, Bhishma was the supreme commander of the Kaurava forces for ten days compared to Drona's five, Karna's two and Salya's one-the last day. He fought reluctantly on the side of theT HTTUKauravasUTH; nevertheless, he gave it his best effort. At one stageT HTTUArjunaUTH's disinclination to fight him, nearly madeT HTTUKrishnaUTHT Tbreak his vow not to raise a weapon in the war. Not even Arjuna was able to defeat Bhishma because in addition to being a peerless warrior he was blessed with choosing the moment of his death.
In this war, Bhishma vowed not to kill any of the Pandavas, as he loved them, being their grandsire. Duryodhan often confronted Bhishma alleging that he was not actually fighting for the Kaurava camp as he wouldn't kill any Pandava but would let them kill Kauravas. But in fact, Bhishma was the strongest barrier that had protected the Kaurava camp from impending defeat.
The war was thus locked in a stalemate. As the Pandavas mulled over this situation, Krishna advised them to visit Bhishma himself and request him to suggest a way out of this stalemate. Bhishma knew in his heart that the Pandavas were righteous and chaste, and that he stood as the greatest obstacle in their path to victory, so when they visited Bhishma, he told them that if faced by a woman in battle he would cease to fight and not lift weapons against her.
The Pandavas were initially not agreeable to such a ploy, as by bringing a woman to the battleground they would disgrace themselves, but Krishna suggested a clever alternative. And thus, on the next day - the tenth day of battle -T HTTUShikhandiUTHT Taccompanied Arjuna on the latter's chariot and they faced Bhishma who put his bow and arrows down. He was then felled in battle by a reluctant, ashamed and tearfulT HTTUArjunaUTHT Tpierced by innumerable arrows. As Bhishma fell, his whole body was held above the ground by the shafts of Arjuna's arrows which protruded from his back, and through his arms and legs. Seeing Bhishma laid on such a bed of arrows humbled even the gods who watched from the heavens in reverence, silently blessing the mighty warrior.
Bhishma was succeeded byT HTTUDronaUTHT Tas the Commander-in-Chief. Bhishma lay on the 'bed of arrows' till the end of the battle, bound by his vows and chose to die only after learning that theT HTTUPandavasUTHT Thad won. One of his last acts was to impart his final instructions on administration and kingcraft to Yudhisthira.
TDeathT
It is believed that Bhishma died after the age of 350 years. The relation between Bhishma and Pandavas/Kauravas is described as that of a grandsire.
Although their descendence was in the following generations
Maharaj HASTIN (founder or the Great HASTINAPUR empire) -> (many generations) -> Bharat ->T HTTUShantanuUTHT T-> Bheeshma, Chitrangada, Vichitraveerya ->T HTTUDhritarashtraUTHT T&T HTTUPanduUTHT T->T HTTUPandavasUTH&T HTTUKauravasUTH
but practically, Bhishma and the Pandavas would be 4 generations apart as Bhishma was himself a prince of marriagable age when his father Shantanu married Satyavati, so Chitrangad and Vichitravirya were more like sons than brothers to Bhishma. When both Chitrangad and Vichitravirya died heirless, MaharshiT HTTUVed VyasUTHT Twas called upon to revive the lineage. Then Dhritarashtra, Pandu and Vidura were born. The Pandavas and Kauravas were the next generation, so although addressed as grandfather, Bhishma was equivalent to their Great-Grandfather.
When Bhishma died, he was the eldest living ancestor to the equivalent of 5 generations as the Pandavas themselves were grandparents. Their only living heir wasT HTTUParikshitUTH,T HTTUArjunaUTH's grandson, the son ofT HTTUAbhimanyuUTHT TandT HTTUMatsya princess UttaraUTH.
TPassing Away of BhishmaT
Bhishma was a great warrior and a wonderful personality. As the Kauravas were losing the battle, Duryodhana approached Bhishma one night and accused him of not fighting the battle to his full strength because of his affection for the Pandavas. Bhishma, greatly angered, immediately he picked up five golden arrows and chanted mantras declaring, "tomorrow I will kill the Pandavas with these five golden arrows". Duryodhana, not having faith in Bhishma's words, asked Bhishma to give him custody of the five imbued golden arrows saying that he would keep them with him and return them the next morning.
Long back when Pandavas were in living in the forest Duryodhana once came to the forest to flaunt his material opulence in contrast with the Pandavas who were living in exile due to his wicked usurption of their kingdom, thus displaying his venom and hubris. He placed his camp on the opposite side of a pond where the Pandavas used to stay. Once while he was taking bath in that pond there the heavenly princes named Gandharvas came to take bath.
Duryodhana could not tolerate this and he had a fight in which the Gandharvas captured him. On the request of Yudhisthir, Arjuna saved Duryodhana and set him free.Duryodhana was ashamed but being a kshatriya he asked Arjuna what benediction or boon would Arjuna like. Arjuna replied that he would ask for the honor gift later when he needed it.
It was during that night that Krishna reminded Arjuna of his unsatisfied boon and told him to go to Duryodhana and ask for the five golden arrows. When Arjuna came and asked for the five golden imbued arrows Duryodhana was shocked, but knowing full well his honor and duty as a kshatriya declared "I will give you the five golden arrows but can you please tell me who told you the five golden imbued arrows existed in the first place?" Arjuna smilingly replied "Who else other than Shri Krishna could have advised me". After Duryodhana honorably kept his word and gave the five golden arrows imbued with a lifetime of austerity and power by Bhishma, the haughty arrogant prince Duryodhana broke his customary manner and conceded to himself privately "All of the rishis say Krishna is the Supreme God, maybe they are right", being thus shocked and convinced by Arjuna's knowledge of the very existence of the five golden arrows, Duryodhana secretly got on his knees and said a quick prayer to Krishna.
Duryodhana again goes to Bhishma, informing him of all that happened and requesting another five golden imbued arrows. To this Bhishma laughed and replies "That is not possible child. The will of the Lord is Supreme and undeniable. I have already spent the merits of my lifetime of celibacy and austerity in those five arrows, a potency strong enough to end all the five Pandavas. However, Krishna, being the Supreme Lord has foreseen this, knowing past, present, and future as He alone can, and has thus arranged for you to voluntarily give up the five golden arrows, imbued with the power and potency of my lifelong austerities. I cannot imbue another five arrows, having spent all of the merits of my austerities. However, tomorrow I shall fight like a lion, and this time either I will kill Arjuna or I will make Lord Krishna break His promise of not picking up any weapons during the war". On the next day there is an intense battle between Bhishma and Arjuna. Although Arjuna was very powerful, but he was no match for Bhishma. Bhishma soon shot arrows which cut Arjuna's armour and then also his Gandiva bow. Arjuna was helpless before the wrath of the grandsire.
As Bhishma was about to kill Arjuna with his arrows Lord Krishna could not tolerate his devotees plight and He immediately threw down the chariot reins and jumped off the chariot onto the battlefield, lifted a chariot wheel and charged Bhishma, determined to send Bhishma to Death's abode. Arjuna tried to stop Lord Krishna but the Lord says that in order to protect my devotee I must break my own promise. Eventually however, Arjuna convinces Krishna to return to the chariot and put down the wheel, promising to redouble his determination in the fight, all the while Bhishma stood with folded palms and tears in his eyes, awed by the beauty of the wrath of the Lord and the intense love that God bears for his friends, so great that He is willing to endure the censorship of ignorant foolish men. Later the Lord tells Arjuna how he may bring down the old grandsire, through the help of Sikhandhi the woman-man, using Sikhandi as a shield, thus shot merciless arrows at Bhishma piercing his entire body, thus finally did Bhishma give up the fight, focusing his life force and breath, sealing the wounds, and waiting for the auspicious moment to give up his body.
Source(s):Srimad Bhagavatam 1st Canto Chapter 9, slokas 1 - 49 by His Divine Grace AC Bhaktivedanta Swami Prabhupada