Vyuha
Vyuha is the pattern or formation of the army before the war commences. On each day, the Kauravas and the Pandavas had their respective armies formed in a Vyuha.
On the 12th day of war
After Partha went out for slaying the Samshaptakas, Drona then, at the head of his troops arrayed for battle, proceeded for seizing king Yudhishthira the just. Seeing that Drona had arrayed his forces in the form of a Garuda, Yudhishthira disposed his troops in counter array in the form of a semi-circle.
In the mouth of that Garuda was the mighty car-warrior Drona himself. Its head was formed by king Duryodhana, surrounded by his uterine brothers. Kritavarman and the illustrious Kripa formed the two eyes of that Garuda. Bhutasharman, and Kshemasharman, and the valiant Karakaksha, and the Kalingas, the Singhalas, the Easterners, the Shudras, the Abhiras, the Dasherakas, the Shakas, the Yavanas, the Kambojas, the Hamsapadas, the Shurasenas, the Daradas, the Madras, and the Kalikeyas, with hundreds and thousands of elephants, steeds, cars, and foot-soldiers were stationed at its neck. Bhurishravas. and Shalya, and Somadatta, and Bahlika, these heroes, surrounded by a full Akshauhini, took up their position in the right wing. Vinda and Anuvinda of Avanti, and Sudakshina, the ruler of the Kambojas, stationed themselves in the left wing at the head, however, of Drona's son Ashwatthaman. In the back (of that Garuda) were the Kalingas, the Ambashthas, the Magadhas, the Paundras, the Madrakas, the Gandharas, the Shakunas, the Easterners, the Mountaineers, and the Vasatis. In the tail stood Vikartana's son Karna, with his sons, kinsmen and friends, and surrounded by a large force raised from diverse realms, Jayadratha, and Bhimaratha, and Sampati, and the Jayas, and the Bhojas, and Bhuminjaya, and Vrisha, and Kratha, and the mighty ruler of the Nishadhas, all accomplished in battle, surrounded by a large host and keeping the region of Brahma before their eyes, stood in the heart of that array. That array, formed by Drona, in consequence of its foot-soldiers, steeds, cars and elephants, seemed to surge like the tempest-tossed ocean (as it advanced to battle).