All about Dronacharya

In the Mahabharata epic, Drona or Dronacharya plays a key role and is one of the major characters. He was the Guru of the Kaurava and Pandava princes. He was an incarnation of Brahma and an avatar of Brihaspati. The son of Sage Bharadwaja, he was an expert in military arts, including the Astras (divine weapons).
Drona did not emerge from a woman's womb but from a vessel made of a leaf. So he got the name 'Drona,' meaning 'vessel made of a leaf.'
Birth and Education
Sage Bharadwaja went to the Ganga River with his companions to perform his ablutions. There he saw a beautiful Apsara, Ghritachi. Filled with desire, his body produced semen. He captured it in a vessel called a Drona, and Dronacharya sprang from the fluid thus preserved. Dronacharya was born in poverty. He studied Dharma and military arts like archery and became an expert. Drupada, the prince of Panchala, was a fellow student and close friend.
Drona’s wife
Dronacharya’s wife, Kripi, was the sister of Kripa, the teacher of the Hastinapura princes. Kripa and Kripi, too, had been born outside the human body. Drona and Kripi’s son was Ashwatthama. Devotees worship Kripi as Shitala Mata in Sheetla Mata Mandir, Gurgaon.
Drona’s son
Ashwatthama, Drona’s son, sided with the Kaurava army. He is the avatar of one of the eleven Rudras and also one of the seven immortals or Chiranjivi. Along with Kripa, his maternal uncle, Ashwatthama, is supposedly a living survivor of the great Kurukshetra War.
Drona and Parasurama
On hearing that Parasurama was giving away his possessions to Brahmins, Drona approached him. But he had only weapons to give Drona. He gave them to Drona and told him how to use them. Thus, Drona obtained Parashurama’s weapons and his title 'Acharya, ' thereby becoming Dronacharya.
Drona and Drupada
Drona desired freedom from poverty. Remembering Drupada's childhood promise of giving him half his kingdom if he became king, Drona approached him for help. However, Drupada refused, saying that friendship was possible only between equals. A humiliated Drona swore revenge.
Drona in Hastinapura
While in Hastinapura, Drona met the young Kauravas and Pandavas and impressed them with his skills by retrieving a ball of theirs that had fallen into a well. Uttering some Vedic chants, he threw some blades of grass into the well like spears, one after the other. The first blade got embedded in the ball, the second stuck to the first, and in this manner, the blades formed a rope of grass. Drona then pulled the ball out easily.
The excited princes took Drona to Bhishma, their grandfather. On hearing what had happened, Bhishma realized that he was Drona.
Bhishma asked Drona to become the Guru of the Kuru princes. Drona set up his Gurukula near the city. Princes from kingdoms near and far studied under him. The village became known as Guru-Gramam ("guru" - teacher, "grama" - village), which later became Gurgaon.
Drona’s favorite student was Arjuna. He promised Arjuna that he would make him the best archer on earth and imparted special knowledge of the Astras to him.
Drona and Ekalavya
The son of a Nishada chief (tribal), Ekalavya wanted to learn under Dronacharya. But Drona did not accept him as a student, as Ekalavya was not a Kshatriya prince. Also, Eklavya's father was a commander of the Magadha kingdom ruled by Jarasandha. Hastinapur and Magadha had a troubled relationship. Drona felt that training Eklavya would make him disloyal to Hastinapur, the land that gave him shelter. It became another reason to reject Eklavya.
Undeterred, Ekalavya practiced on his own after making a clay image of Drona, who he regarded as his teacher. Soon, he became so skilled that he posed a threat to Arjuna. To eliminate this threat, Drona demanded Ekalavya’s right thumb as Dakshina.
Without any hesitation, Ekalavya cut it off and gave it to Dronacharya, knowing that it would impact his archery skills. Nowadays, people perceive Ekalavya as a subaltern hero, while Drona is his upper-caste oppressor.
Drona and Karna
Dronacharya also rejected Karna, who he thought was the son of a charioteer. Karna later gained knowledge of weapons and military arts from Parasurama. Parasurama gifted him his knowledge of divine weapons and Astras, including Vijaya (bow). He also declared Karna as his equal in warfare.
Drona’s revenge
Drona had always dreamt of taking revenge against Drupada. He sent Arjuna and the other Pandavas to capture his foe. Arjuna conquered Drupada, and Drona had his revenge by taking half of Drupada's kingdom, thus becoming his equal. Though he forgave Drupada, Drupada sought revenge. He conducted a Yajña for a son who would kill Drona and a daughter who would marry Arjuna. In this manner, Dhṛiṣhṭadyumna, Drona’s killer, and Draupadī were born.
Drona as warrior
Bhishma described Drona as a Maharatha, meaning a warrior capable of fighting 7,20,000 warriors simultaneously.
Dronacharya was trained by his father, Bharadwaja, and Agnivesha, a disciple of Parashurama, to use all manner of weapons. He received many divine weapons from Parashurama. He did severe penance to gain the powerful Brahmashirsha Astra and Brahmanda Astra from Sage Agastya. He also got the rare Narayanastra for his hospitality to Lord Vishnu. His ancestor Angirasa gave him a divine bow. As a warrior, Drona had no rivals and was very powerful.
Drona also had the mighty sword of Lord Brahma. The Gods created this primordial weapon to destroy evil. Its name was Asi, and it was the primary energy behind all weapons.
Dronacharya and the war
Dronacharya was undoubtedly one of the most fearsome warriors in the Kurukshetra war. He killed thousands of Pandava soldiers singlehandedly. After Bhishma was mortally wounded, he became the Chief Commander of the Kuru army for 5 days of the war.
Death of Abhimanyu
On the 13th day of the war, Arjuna’s son, Abhimanyu, broke into the spiral-shaped battle formation called Chakravyuha. It was part of Dronacharya’s strategy. Only Arjuna and Krishna knew how to enter and exit the formation. Abhimanyu knew how to penetrate the Chakravyuh but not how to exit from it. He got trapped within it and was killed.
Death of Drona
On the 15th day of the war, Drona used the Brahmastra against the Pandava army. He also invoked the Brahmanda Astra. However, the Sapta Ṛiṣhis requested him to retract the weapon as it could unleash tremendous destruction. Dronacharya agreed and retracted it.
Lord Krishna hatched a plan to weaken Drona. He told Yudhishthira and the other Pandava brothers that if Drona believed that Ashwatthama was dead, it would make him vulnerable.
So Krishna told Bhima to kill an elephant called Ashwatthama and tell Drona that he had killed Ashwatthama. Bhima did as instructed. But Drona did not believe Bhima. Knowing that Yudhishthira would never tell a lie, he asked Yudhishthira if Bhima’s claim was true. Yudhishthira replied that Ashwatthama was dead but that it was an elephant. At this time, the Pandava soldiers blew trumpets and conches, drowning out most of Yudhishthira’s words. Drona heard only that "Ashwatthama is dead."
As Ashwatthama was a Chiranjivi (immortal), Drona felt doubtful and did not believe Yudhishthira. He stepped down from his chariot, laid down his arms, and began meditating. He closed his eyes, and his soul traveled to heaven to find Ashwatthama's soul. Seizing the opportunity, Dhrishtadyumna beheaded Drona. It is said that Yudhishthira's chariot, which used to float in the air from the beginning of the war because of his high virtue, dropped down to earth after this. Yudhishthira even went to hell briefly after his death for this unethical deed. It was the only unethical act he committed in his entire life.
Conclusion
Though he took sides with the evil Kauravas in the Mahabharatha war and did not treat Ekalavya and Karna well, Drona is a figure who commands respect and reverence. The Government of India created the Dronacharya Award for excellence in sports tutelage to acknowledge and reward the best sports teachers and coaches in India and as a way of honoring Drona.
Gurgaon (meaning "village of the Guru") city is believed to have been founded as "Guru Gram" by Dronacharya on land that Dhritharashtra had given to him as a reward for teaching martial arts to the Kuru princes. One can still find the 'Dronacharya Tank' in Gurgaon city, as well as a village called Gurgaon. The Haryana Government has restored the original name, so Gurgaon has become Gurugram again.