The Pandavas had appointed Dhritadhyuman [Draupadi's brother] as the general of their army. The Kauravas obviously appointed Bhishma as the general of their army.
Long before the battle had started Bhishma had promised Duryodhana that he would not kill the five Pandavas but would cause maximum havoc to the Pandava army. He did. On the first day of the battle, the Pandava soldiers literally ran from Bhishma out of fear from his arrows. He was in a word a terror to the entire Pandava army.
Arjuna's son Abhimanyu could not bear the havoc caused by Bhishma. He came out with his arrows blazing at the grandsire. Though Abhimanyu was able to contain Bhishma for a short time, eventually Bhishma came on top and soon Abhimanyu had a broken chariot and had to withdraw from the battle.
Elsewhere in the battle, Uttara, the son of Virata first engaged in the battle with Shalya. As they both fought, the younger Uttara started gaining an upper hand. However Shalya was a more experienced fighter and at the last minute, Shalya fired an arrow straight in Uttara's heart and Uttara was unfortunately killed. Uttara's brother Shweta could not bear this and he started a battle against Shalya.
Shweta fought so brilliantly that Shalya was soon without a chariot, without weapons and even without his bodyguards. Shweta destroyed it all. As Shweta was about to complete his kill and aimed for Shalya, seven warriors from the Kaurava side came forward to stop Shweta. Shweta fought with all the seven warriors and was even able to push them back....However Shalya escaped by this time....Shweta continued fighting so brilliantly that the grandsire Bhishma himself came to take on Shweta. Shweta hurled his weapons at Bhishma and was successful in even destroying Bhishma's chariot.
Bhishma angrily destroyed Shweta's chariot in return.
However Shweta had age on his side. Without bothering about the lose of the chariot, Shweta started attacking Bhishma from foot. Shweta was so good that he was beginning to gain a upper hand in the fight, when the Kauravas realizing the danger to their general, immediately whisked away Bhishma on another chariot.
It was from the chariot that Bhishma aimed his powerful weapons at Shweta and unfortunately for the Pandavas, Virata lost his second son also in the first day of battle.
Thus the first day of the battle ended with the Pandavas suffering huge losses at the hands of the terrible Bhishma. Bhima, the Pandava killed many Kaurava soldiers but he was nowhere near to the damage done by Bhishma.....
Yudhishtara was broken hearted with the events of the day. Krishna eventually using all his tact and diplomacy was able to cheer up the sad Pandava leaders.
The second day of the battle started with Arjuna deciding to take on Bhishma himself. Bhishma was surrounded by Shalya, Bhagadatta, Bhusrisravas, Duryodhana and some of his brothers.
Krishna with all his driving skills managed to get Arjuna close to Bhishma as Arjuna almost casually disposed all these warriors who surrounded Bhishma. However when Arjuna was about to start the fight with Bhishma, Bhishma was surrounded by Drona, Kripa, Duryodhana and Sala to protect him.
But today none of the warriors were a match for Arjuna. All the other warriors fell back and Arjuna and Bhishma faced each other and fired arrows at each other looking hell bent of destroying each other.....
As they were firing arrows, Arjuna watched with horror as one of Bhishma's arrows hit Krishna. Arjuna was too seasoned a warrior to react to it. Keeping his anger aside, he aimed straight at Bhishma's charioteer and killed him instantly. Bhishma had to momentarily stop fighting because of the death of his charioteer. It was only then that Arjuna spared a glance at Krishna and realized that the wound was only a flesh wound and continued with the battle. The battle between Arjuna and Bhishma went on for the entire day and neither looked like they could best each other....
Elsewhere, Bhima killed the King of Kalinga and his sons in the battle.
Drona and Dhristadhyuman fought hard and long. However this battle was won by experience and not age. Drona was so able to destroy Dhrishtadhyuman's chariot and was about the kill Dhrishtadhyuman, when the others in the Pandava army whisked away Dhrishtadhyuman from there.
The sun set and the battle closed for the second day as neither Arjuna nor Bhishma relented that day....
The outcome of the war cheered up the Pandavas slightly....
The battle on the third day started and with a great roar both the sides clashed. This time Arjuna went on a rampage and started mercilessly attacking the Kaurava soldiers. The Kaurava soldiers fled from the Pandava almost afraid of him.
For the first time since the war started Duryodhana and Bhima met each other in battle. With all his pent up anger, Bhima hurled his weapons at Duryodhana. Unable to match the ferocity of the attack Duryodhana had to hide himself in the deck of the chariot to escape from the weapons. Duryodhana was ashamed that he had to hide in his chariot to escape the wrath of Bhima and was cursing himself. That was when he saw that his soldiers were running away from the battlefield unable to bear the onslaught of Arjuna.....
Duryodhana angrily pursed his lips and went in search of Bhishma. Duryodhana was shocked to find that Bhishma and Drona were the only two Kauravas who were fighting against the Pandavas. The others were too busy running away.
But that still did not stop the Duryodhana from senselessly confronting the grandsire, 'Now...I see everything! You...the great Bhishma...you are partial to the Pandavas...Though you claim to be fighting on my side, you are helping the Pandavas. I know that the Pandavas together are not a match for you....Do you want me to believe that the Pandavas have actually destroyed our army and our soldiers are running away from the battlefield with you as our general....' Duryodhana looked at Bhishma with a curl in his lips. 'You are not fighting to your capabilities...If you were, the Pandavas would be dead by now!'
When was Duryodhana going to understand....Bhishma wondered as he looked around him. 'Duryodhana! I have told you before and I am telling you again. The Pandavas cannot be killed in battle...Not by me, not by you, not by anyone!' Bhishma actually looked a little wistful. 'I wish you would believe me that I am fighting as well as I can....And still you accuse me of not fighting to the best of my abilities...' Bhishma did not say it but his eyes conveyed the sorrow in his heart. The prince whom he had sworn to protect was doubting him....Bhishma looked angrily at Duryodhana before the prince could open his mouth and say something else to hurt him and angrily turned to the Pandava army. 'Watch what I do now!'
Duryodhana watched the stiff back of the grandsire and did not say anything.....
After that the Pandavas saw exactly what Bhishma was capable of when he was angry. Bhishma hacked through anyone or anything which came in his way. He cared about nothing and just destroyed the Pandava army.
'Arjuna!' Krishna growled as he heard the screams of the Pandava soldiers. 'Bhishma!' He said pointing at towards what seemed like a terrible whirlwind of destruction.
Arjuna nodded his head as Krishna quickly turned and drove the horses straight towards Bhishma. Bhishma did not care whom he faced....whether it was Arjuna or anybody else, he decided to destroy anybody who came in his way. Bhishma fired the arrows and Arjuna patiently cut all of them...Bhishma attacked again and Arjuna defended again....Getting more and more agitated, Bhishma picked out more and more powerful weapons. Though Arjuna was able to stop the weapons....everyone....every single one of the Pandava soldier realized that Bhishma was in fact the better between the two of them.
Bhishma was fighting like he was possessed, hell bent on annihilating the entire Pandava army as if he wanted to end the very war on that day. Arjuna on the other hand fought placidly. He just stopped Bhishma, but he was not aggressive like the Kaurava general....
Arjuna was beginning to feel uneasy. He knew something was wrong....terribly wrong.
That was when he saw the Dark Lord throwing the reins of the chariot in disgust. He looked at Arjuna with such a pure undisguised anger that Arjuna shivered for a few minutes. Krishna turned and looked at Satyaki who was standing nearby, with his eyes blazing. 'There is no use trusting in Arjuna anymore! I thought he was a good warrior and I wanted to guide him and look....' Krishna pointed at Bhishma with anger. 'Look at the way he is fighting....Pathetic!' Krishna shook his head. Krishna got down from his chariot and from the battlefield picked up the broken wheel of a chariot.
'If Arjuna will not do it....I will!' Krishna started swirling the chariot wheel high above his head. 'Whoever wishes to run.....can do so now....whoever is left behind....I am going to kill them....All of them. I am going to destroy the entire Kaurava army today!' Krishna advanced towards Bhishma with anger. 'And I start by killing Bhishma!'
Anyone who had seen the blazing Krishna would have trembled and fled. But Bhishma was too seasoned a warrior and too wise a man to even worry about it. He threw down his weapons a great peace stealing on his face. 'Madhusudhana! Do it now! Please kill me right now, with your own hands! Once you have killed me....I am sure to attain heaven!' Bhishma practically begged Krishna. 'Please kill me and put an end to my life!'
Arjuna watched the entire scene his heart thundering. The Dark Lord had trusted him....The Dark Lord had wanted him to fight, with everything he had and to the best of his potential...The Dark Lord had promised that he would not raise any weapons in the war...He, Arjuna had failed in keeping up the promise because of which Krishna was breaking his promise and going to kill Bhishma...No! He would not let Krishna break his promise.
Without realizing it Arjuna ran forward clutching Krishna's feet. Krishna may have noticed him or may not...Krishna was so incensed that Arjuna did not even know what his Krishna was thinking....
Krishna stubbornly went forward the chariot wheel still in his hands. 'Krishna! Please do not break your promise! Please you said....you would not raise weapons....Please! Do not break your word!' Arjuna begged.
'You are not fighting, Partha! What you are doing is not fighting...' Krishna started yelling. 'The man has practically destroyed your army. Your soldiers are running away from fear of the man and all you can do is defend against him....No!' Krishna looked at Arjuna with such an angry expression making Arjuna wish that he would never see that expression in his Krishna's face ever....'If you won't kill the man...I will!'
Arjuna managed to calm himself and spoke slowly. 'Krishna! I will fight! I will fight the exact way you want me to fight...I will fight to the best of my abilities...I will not fight my grandfather....I will fight the man who is destroying my army....Please Krishna! Just put down the wheel....I will fight...Just guide me!' Arjuna spoke with utter sincerity in his voice.
Krishna looked at Arjuna and then looked at Bhishma. Bhishma knew the exact minute when Krishna believed Arjuna. Krishna gave a genuine smile to Arjuna and dropped the chariot wheel. Arjuna led Krishna back to the chariot....
True to his word, Arjuna fought with his body, heart, mind and soul....Krishna who was willing to break his promise to protect his devotee could only smile as he realized that Arjuna was beginning to understand his teachings...... It was on that day that Arjuna single handedly destroyed almost close to ten thousand people fighting in chariots and seven hundred elephants....
[After this day, the war more or less went in favour of the Pandavas...On the tenth day, using the help of Shikandi, Arjuna killed Bhishma....]