Book 4: Virata
During the brothers' 13th year in exile, they must live in disguise, and will suffer another 12 years in exile if they are detected. They decide to take residence in the court of King Virata, each assuming a secret identity that will endear them to the king. Yudhisthira assumes the identity of a brahmin and skilled gambler, Bhima becomes a skilled cook, Arjuna poses as a eunuch, Nakula will act as a horse trainer, and Sahadeva will herd the cattle. Draupadi poses as a maidservant skilled at hairdressing so she can maintain her independence. Virata ecstatically receives them, well aware that these are not typical people posing in their roles.
While in the kingdom, Draupadi attracts the attention of Kicaka, who tries to rape her in an attempt to make her his. Draupadi, after suffering multiple indignities as a princess in disguise, appeals to Virata, who is unsympathetic since he didn't witness the attack. Bhima, though, agrees to help Draupadi, and kills Kicaka, mangling his body in the manner only a Gandharva could. Kicaka's kinsmen find the dead Kincaka and immediately conclude that Draupadi is to blame, so they appeal to Virata to let them burn her on Kicaka's funeral pyre, and Virata assents. When Draupadi is bound and taken by Kincaka's kinsmen, Bhima slaughters all 105 of them in the forest. Virata, fearing the wrath of the Gandharvas, frees Draupadi, but Draupadi urges him to let her stay for another 13 days, which will please the Gandharvas.
During this year, Virata's son Uttara is accosted by Duryodhana's men, who try to steal his cattle. Arjuna heroically accompanies Uttara and saves his cattle, but Arjuna almost gives up his identity to his opponents. Virata hears that Uttara has saved his cattle, and Yudhisthira infuriates the king when he says that the eunuch is to thank for the deed. Virata strikes Yudhisthira and gives him a bloody nose, but Yudhisthira doesn't let the blood fall on the floor, so that he does not have to seek retribution for the assault. When Uttara returns, he confirms that the eunuch saved the day. Soon after, the 13th year is over, and the five brothers and Draupadi reveal their real identities. Virata offers them his kingdom. Arjuna's son Abhimanyu marries Virata's daughter.
Book 5: Perseverance
With the 13 years of exile over, Yudhisthira is now becoming aware that Duryodhana has little intention to return his rightful half of the kingdom. Krsna instructs Yudhisthira to go plead a case for a peaceful transfer of power and, in the event that Duryodhana refuses, to then declare war. Yudhisthira and his brother Bhima are reluctant to go to war, while Draupadi demands war to make right for the indignities and humiliation she suffered during the 13 years of exile imposed by Duryodhana. Visnu promises that even though he would supply men to Duryodhana, he will throw his support behind Yudhisthira and his brothers.
Yudhisthira follows Krsna's instructions and appeals to Duryodhana for a peaceful transfer, but Duryodhana refuses. Krsna implores Dhrtarastra to keep his son from initiating a war and destroying the Bharata lineage, telling him that Duryodhana and Yudhisthira could rule together in peace. Dhrtarastra is won over, and appeals to his son, even bringing in his Duryodhana's mother Princess Gandhari to reprimand him for his foolishness. Even Bhisma disagrees that Duryodhana should go to war with the Pandavas.
Nevertheless, Duryodhana is resolved to go to war. Krsna appeals to Karna to join the Pandavas, noting that he is technically the eldest son of Pandu. But Karna refuses, saying he was abandoned by his mother, that Duryodhana has been good to him and it is too late to change allegiances. As the war grows closer, Duryodhana appoints Bhisma as his commander, and Yudhisthira appoints Draupadi's brother Dhrstadyumna as his own. Arjuna reminds Yudhisthira that he could destroy Duryodhana's forces instantaneously with a celestial weapon, but that it would be improper. The two sides march to battle.
Book 6: Bhisma
As the battle begins, both Duryodhana and Yudhisthira put forth fearsome, massive armies. Arjuna instructs Krsna to drive his chariot above the battlefield so that he gets a good view of the beginnings of the battle. Arjuna then throws down his weapons in despair over the fact that so many of his kin are about to meet their destruction. Krsna then explains the Bhagavad Gita to Arjuna, giving him a comprehensive explanation of his dharma. As Krsna explains, it's Arjuna's responsibility to act on his own dharma with detachment, since actions are what will result in Krsna's goodwill. Krsna then shows Arjuna his true godly form, and Arjuna is appreciative and awestruck.
The battle begins with Yudhisthira asking for permission from the leaders of the opposing force to face them in battle. Those leaders all admit that they are beholden to Duryodhana's army by money, but that they give Yudhisthira his blessing to fight them and wish him victory. The fighting is bloody from the start, with Bhisma showering the Pandava forces with arrows. The fortunes of the two forces are constantly changing. The Pandavas have a fearful army, and Duryodhana suffers injuries in battle, but the tables turn and Bhima also suffers injuries. At first, Duryodhana is pleased by Bhisma's resolve to defeat the Pandavas, but soon grows impatient and threatens to replace with Bhisma with Karna.
Throughout the first 10 days of battle, Krsna and Arjuna clash over Arjuna's pledge to kill Bhisma, and there are a few times Arjuna has to stop Krsna from killing Bhisma himself, lest he break his vow to not fight in the war. Despite Bhisma killing thousands of Pandava soldiers, he grows tired of killing, and communicates to Yudhisthira that he desires his dharma of being killed in battle. This is when Yudhisthira sends Arjuna and his men to kill Bhisma, and they rain arrows on him. Bhisma chooses to delay the day of his death, as he lays in pain on a bed of arrows, asking Arjuna to prop up his head and feed him water. While Bhisma lays in agony on the bed of arrows, Karna asks for his permission to fight.
In Book 6, "Bhisma," Krsna recites the Bhagavad Gita, perhaps the most historically and culturally significant portion of the Mahabharata for the Hindu religion and its society. Many go so far as to consider the Bhagavad Gita the "fifth Veda," treating it like a crucial fifth amendment to he original four Vedic texts which outline the mythology and ethics of the Hindu religion. The Bhagavad Gita stands as not just an important treatise on dharma, but as the only text in the ancient Hindu tradition that expounds on individual action, and an individual's personal responsibilities when acting on behalf of their dharma. It would become increasingly important to the Hindu faith during the Middle Ages, and informed Mohandas Gandhi's philosophy and methods during the Indian independence movement in the 20th century.
As the scholar Lourens Minnema points out, the Bhagavad Gita essentially centers on a contradiction. Arjuna is a member of the Ksatriya caste and is one of the most fearsome warriors in the world, meaning that it is his dharma to wage war on behalf of his righteous brother, Yudhisthira. But Arjuna looks down at the battlefield and recognizes many of his kin, and wants to throw down his arms. The conflict between Arjuna's adherence to his personal dharma and the more generalized dharma tenets—which preach non-violence and compromise—inspire Krsna to recite the Bhagavad Gita to explain Arjuna's obligations and resolve the moral quandary.
As Minnema notes, Krsna does this by helping Arjuna recognize matters of scale. There are the immediate concerns of the individual, and then there are the greater concerns of fate and the cosmos. Krsna makes a point that by following his own personal dharma—as every man should—Arjuna is in fact satisfying what fate has designed for him. To act in any other way, be that by another man's dharma or by tenets that do not apply to oneself, would be to violate that dharma and commit a sin.
Action is central to Krsna's formulation of dharma, as Krsna explains to Arjuna that only through action does a man fulfill his dharma. He recommends that Arjuna undertake those actions with detachment, freeing this own personal desires from his need to perform the duties of dharma. Minnema points out that desire is highlighted in the Bhagavad Gita as the main thing that undermines acting in dharma, highlighting that dharma is as much a sense of duty as it is an acknowledgment of destiny.