Mbh 6.82.1b

Near unto every elephant were placed seven cars, and near unto every car were placed seven horsemen. And behind every horseman were placed seven bowmen, and behind every bowman were seven combatants with shields. And thus, O king, thy army, arrayed by mighty car-warriors, stood for fierce battle, protected by Bhishma. And ten thousand horses, and as many elephants, and ten thousand cars, and thy sons, all equipped in mail, viz., the heroic Chitrasena and others, protected the grandsire. And it was seen that Bhishma was protected by those brave warriors, and those princes themselves of great strength, accoutred in mail, were (in their turn) protected by him. And Duryodhana accoutred in mail sat upon his car on the field, and possessed of every grace, looked resplendent like Sakra himself in heaven. Then, O Bharata, loud were the shouts uttered by thy sons and deafening the clatter of cars and the uproar of musical instruments. That mighty and impenetrable array of those slayer of foes, viz., the Dhartarashtras (in the form called) Mandala, (thus) arrayed by Bhishma, began to proceed, facing the west. Incapable of being defeated by enemies, it looked beautiful in every point. Beholding then the array called Mandala that was exceedingly fierce, king Yudhishthira himself disposed his troops in the array called Vajra. And when the divisions were thus arrayed, car-warriors and horsemen, stationed in their proper places, uttered leonine shouts. Accompanied by their respective forces, the brave warriors of both armies, well versed in smiting, and longing for battle, proceeded, desirous of breaking each other’s array. And Bharadwaja’s son proceeded against the king of the Matsyas, and his son (Aswatthaman) against Sikhandin. And king Duryodhana himself rushed against the son of Prishata. And Nakula and Sahadeva went forth against the king of the Madras. And Vinda and Anuvinda of Avanti proceeded against Iravat. And many kings together battled with Dhananjaya.