Guru Dronacharya, was not only the supreme preceptor of archery but also the spontaneous archer , pupil of Master Parashurama and great commandant. In this Jayasahinta means Mahabharta , his contributions can not be characterized because it is like to show the candle to the sun for such great personality.He was the creative being of those warriors who sacrificed their life in this crusade.It means he was the only master of disciples like Arjuna, Bheema, Yudhisthira , Duryodhana ,Dhristdhumana , Ashwathama etc.
Guru Dronacharya was born in Brahmin family and got his education of arms from guru or master Parashurama.There he met from Drupad who was classmate of him.Drupad promised him that he will help him at the time of need.He married with the sister of Kripacharya,who was family teacher for kuru clan, named Kripi. Kripi was the mother of Ashwathama .Guru Dronacharya was a contented Brahmin and fulfilled his all requirement from his small earning. But he loved his son Ashwathama very much.
But when he saw one day, that his wife was unable to feed the cow's milk to her son then she was feeding water of rice mixed with sugar. So that Ashwathama could have an illusion of cow's milk.Then , to feed the cow's milk to his son , he desired to wealth accumulation so he went his classmate Drupada. But Drupada refused to recognize him and banished him to disgrace.
Saddened by the behavior of his classmate , he went to his wife's brother Kripacharya to avenge from Drupada. Where, for education of Kuru princes , Bheeshma placed dronacharya in Hastinapur. He granted the technique and skill to operate arms to all kuru princes.
Arjuna was the his favorite disciple and he had the greatest affection with Arjuna after his son. Therefore, he blessed Arjuna to be greatest archer in the earth.
So , to fulfill his promise he had cut the Eklavya's thumb and refused to teach pupil like Karna.
He gave the great warrior like Arjuna to Aryawarta but due to reprisal spirit with Drupada ,firstly he captured Drupada with the help of Pandavas and took away his half state of Panchala. After this insult , Drupada prepared his son Dhristradhumna to destroy the Guru Dronacharya.
Now we will discuss the some functions of Guru Dronacharya , wherefore he had to stand out with wrongdoing or injustice or 'Adharma' in this crusade. Firstly he said nothing in that assembly where cloths stealing of woman like the Droupadi performed. Because his justice vision was covered by the endearment of his son Ashwathama. After that ,he fought with the side of Kauravas by knowing everything.
But after that , for slaughter of Abhimanyu, son of Arjuna, the history will never forgive him because Abhimanyu was brutal assassinated by several warrior while he was general of kaurava's forces.
A father whose eyes are covered with the bar of endearment of son and consequently he can not judge the light and dark or 'Dharma' and 'Adharma' then he is not only harming his son but is loosing his soul.
I believe that the assassination of Guru Dronacharya by the hand of Dhrishtadyumna can be a deception but for the victory of justice and truth it was necessary. Because the conquest of justice and truth or 'Dharma' was not possible while the great warrior Dronacharya was alive. And 'Dharma' is not such a thing that to be made the keep of 'Adharma' due to a 'Dronacharya'.
Thank you.