Yudhisthira Tells a Lie

After the fall of Bhishma, the Kauravas felt great void in their heart, and felt that their strength would be inadequate to face and defeat Arjuna and Sri Krishna combine unless Karna takes up the reigns of leading the Army. However, when approached, Karna declined to take the responsibility saying, "Guru Drona will be the ideal choice as the Chief Leader for Kaurava Army." Thus from 11th to 15th day Acharya Drona took the command in his hand and caused great destruction to Pandava Army. Sri Krishna and Arjuna became nervous and were worried about the outcome. Drona was a great warrior with supreme expertise in the game of war and all the instruments of war. It was not possible for anyone to defeat him.
Meanwhile Sri Krishna reminded Bhima about his powerful son Ghatotkacha born of demon wife Hidimbi! Ghatotkacha had special supernatural powers of getting invisible, smaller or larger in size, etc. at will. Sri Krishna suggested Pandavas to call this son of Bhima who would wreck havoc in Kaurava army and Karna would be forced to use his Special Vaasavi Astra on him instead of Arjuna.
Accordingly Bhima wished Ghatotkacha to come to Kurukshetra and indeed, as soon as his father wished, as promised by him, this great and powerful warrior was there in front of Bhima and Sri Krishna. He was told to fight and annihilate the Kauravas army next day to which he gladly agreed. Next day the battle began. Karna was in search of Arjuna, but Ghatotkacha obstructed his path. Moreover, Ghatotkacha vomited fire and threw large quantity of boulders and sand on Kauravas. There was total chaos in Kauravas camp. Soldiers were running here and there. Scores of their army men were killed.
Duryodhana now requested Karna to kill this demon otherwise, he said, "Nobody will be alive." Reluctantly Karna had to use 'his one time use' Vaasavi Astra on Ghatotkacha instead of Arjuna. Thus, Ghatotkacha died but saved the life of Arjuna.
Death of Abhimanyu
The death of many stalwarts put Duryodhana in a fix. Next day he arranged his army in an impregnable wheel format known as "Chakra Formation". On the side of Pandavas only Abhimanyu, son of Arjuna was capable of penetrating this format; but he did not know how to come out of it. This teenage lad, however, pleaded with his father and uncles to allow him to enter the enemy ranks and then all of Pandavas would come to help him inside.
Accordingly, seeking blessings of Sri Krishna, Abhimanyu led small army and entered the Chakra formation. Kauravas allowed him to enter but soon sealed off the entry of Arjuna and company. Duryodhana, Dushasana, Jayadratha, and many more Kauravas warriors attacked the lone but brave Abhimanyu who fought gallantly all alone against them all.
Arjuna and others were anxious to reach near him but were obstructed by a large force of Kauravas army men. Sri Krishna was also worried.
Soon inside the circle, Abhimanyu lost his bow, his chariot was broken, and he was without any weapon to defend himself. Standing on the ground without losing his courage, this brave man continued to fight with whatever makeshift weapon he could lay hands on. His whole body was inflicted with wounds from sharp arrows and javelins. Bleeding and dazed at last he fell on the ground.
Kripacharya advised other Kauravas to halt further attacks on the boy as he was helpless and without any weapon. But Jayadratha neglected this sane advice. Without mercy and consideration for the helpless state of Abhimanyu Jayadratha kicked him with his foot and killed him with his sword.
The news of brave Abhimanyu's death spread all over. Kauravas were shouting like victors and Pandavas were angered like cornered lions. Arjuna was deeply grieved and tears rolled down his eyes. His heart however was filled with anger and revenge. He decided to kill Jayadratha in the next chance. The evening halted the battle for the day. Arjuna vowed to kill Jayadratha by evening next day or else give his body up in the burning flames.
End of Jayadratha
Next day the terrified Jayadratha sought protection from Duryodhana pleading, "O Duryodhana, Arjuna and Pandavas would apply all their skills and power to succeed in killing me. How should I protect myself against his sharp lethal arrows? I am afraid I would not live beyond sunset today." Reassuring him Duryodhana said, "O my brother-in-law, how can you think that we would leave any stone unturned to protect you. We would all see that Arjuna does not succeed in his pledge and would himself as vowed will die in flames. Rest assured, O Jayadratha, nothing bad will come to your fate."
All the warriors on Kaurava side surrounded Jayadratha's chariot and prevented anyone approaching him. Jayadratha was almost invisible! Arjuna and Bhima, Yudhisthira and others tried to reach near him but were obstructed by one and all. Exchange of arrows filled the sky. Many soldiers lost their lives. It was almost impossible to attack Jayadratha.
Morning turned to noon, noon into afternoon. There was a faint pal of gloom in Pandavas heart while Kauravas appeared to rejoice.
And at that time, in the hours of approaching dusk, the sky became dark; stars were visible on the horizon. Shouts of victory to Duryodhana were heard while everyone on the side of Pandavas thought that Arjuna would have to keep his vow and die! For everyone thought that sun had set.
Jayadratha dancing with joy lifted himself up to see the darkness of evening sky. He thought he had now no fear from Arjuna. But the wonder of wonder was in stores! The skies were dark because of total eclipse of the sun on that day at that hour and not because it was evening! As Jayadratha was looking in merriment, the eclipse ended and the sun came out. The sun light was bright and then said Lord Sri Krishna:
"O Arjuna, look there is the sun and here this Jayadratha, What are you waiting for. It is still daytime, evening has not yet fallen. Kill Jayadratha."
And the sharp penetrating arrow left the Gandiva of Arjuna to take the head of Jayadratha far off in jungle into the lap of his father!