The War Continues

On the second day Arjuna took command of his army and arranged his men in a special format which gave little scope to Kauravas army to advance and attack the Pandavas. Bhishma had killed Uttar son of king Virata. Shalya had managed to kill Shweta. Pandavas saw great loss of their men. Multitudes of soldiers on both sides were killed.
Sri Krishna Breaks His Vow
Third day.
Bhishma arranged his army in Eagle's format and Pandavas opted for semi-lunar style to counter Kauravas offensive. Bhima attacked Duryodhana with an arrow that made him unconscious, but he was quickly shifted to a safer place. Dronacharya and others came to his rescue. Duryodhana was not happy with Bhishma's way of commanding his army and he was seen to insult old grandsire now and then. Bhishma threatened to quit as the chief, but others persuaded him to remain in the lead.
Now, the ferocious Bhishma attacked Pandavas with force unheard of. Pandavas army was torn apart at tens and hundreds places. Soldiers started running here and there. Scores of them died on the battle-field in their futile attempt to attack or escape the mighty Bhishma.
Sri Krishna told Arjuna to protect his men by attacking the leader Bhishma. There was no other way but to remove Bhishma if Pandavas had to win the war. Everyone intently watched this terrifying battle between the old and the young great warrior.
Arjuna was faltering, many a arrow from Bhishma hit Arjuna. He was bleeding profusely. Sri Krishna thought, "If this continues defeat of Pandavas is not far away." Therefore, in a bid to thwart the onslaught of Bhishma, Sri Krishna lifted the nearby wheel of a broken chariot and ran towards Bhishma as if to put and end to his life! The vow that Sri Krishna would not take to arms was thus broken!
Seeing the Lord Himself rushing towards him, Bhishma dropped his weapons. With tears flowing from his eyes Bhishma spoke thus, "O Keshava, O Merciful, how lucky am I that the Lord of Universe Himself has decided to liberate this ordinary Bhishma from the snares of worldliness. O Madhava, come, be quick, let me die at your hands. Who can be happier and lucky than me to get such an wonderful and rare opportunity."
Sri Krishna was reminded of his vow. He threw away the wheel and retreated back to his chariot. For his Bhakta - devotee - the Lord had broken his vow!
Soon the sunset was in sight. The battle for the day ended. The soldiers returned to their camp.
Fourth day to Tenth Day
The fourth day of the war saw Bhishma in great mood of valour and bravery. The Pandava army was in great disarray due to unimaginable destruction inflicted by the Kaurava Army under the leadership of Bhishma. Even Bhima was hurt at the hands of Duryodhana. This continued for five days more with no victory in sight for either army. And hence the 'think-tank' of Pandavas met and decided to put an end to Bhishma's supremacy somehow. Bhishma although old, was proving a great hurdle in the victory of Pandavas. Arjuna was not ready to fight with him with full vigour. Therefore, it was suggested to bring Shikhandi in picture. As Bhishma had vowed not fight with that eunuch, Arjuna could hit the old man under the cover. It was so decided.
The Great Bhishma Collapses
The battle of tenth day began. Shikhandi was in the front attacking Bhishma. Bhishma however, said, "Get away, O Shikhandi, I do not want to fight with you." Thus the mighty and powerful Bhishma laid down his arms. The arrows from Arjuna's Gandiva penetrated his body. Bhishma fell down. There were so many arrows in his body that when he fell down he was as if lying on the bed of arrows! His head was hanging, which Arjuna supported by three arrows under the head and neck. As is well known Bhishma had the boon to give up his body as and when he decided. The sun was in southern hemisphere, this time. and it was not very auspicious to give up body in this phase of sun movement. Therefore, Bhishma said to Sri Krishna, "O Vallabha, Please take me far off corner of the battle ground after about a fortnight when enters to move in northern hemisphere I would give up the body." Thus was arranged a safe and peaceful shelter for this grand old Kuru.
Sri Krishna suggested Yudhisthira to take lessons on politics, diplomacy, duties of a king, economics, and many other related subjects from dying Bhishma. Accordingly every day after the day's battle was over, Yudhisthira and others would visit Bhishma and take lessons on various topics of art and culture at his holy feet. This is a very thought provoking chapter of Mahabharata.
Then enters the character of mighty and skillful Karna as Bhishma is no more in the lead. Dronacharya next becomes the commander of Kauravas army. The Teacher of Pandavas and Kauravas was equally difficult to dislodge as was Bhishma.