Dronācārya was everyone's teacher, ācārya. Ācārya means teacher. Ācāryam upasaṅgamya (BG 1.2). The military teacher. So Duryodhana, he was military teacher of the Pāṇḍavas also. When all of them were children, they were given under the instruction of Dronācārya. Dronācārya was brāhmaṇa, but he knew the military art. Therefore he was appointed teacher for all the boys, the Kaurava. So . . . but Ācārya, Dronācārya, joined with Duryodhana. Bhīṣmadeva joined with Duryodhana. None of them joined with Arjuna. Because Arjuna or Mahārāja Yudhiṣṭhira was not king at that time. The financial control was not in their hands, and these people, sons of Dhṛtarāṣṭra, they were on the government political power. The financial control was in their hand. So they were giving enough money for maintenance to Dronācārya and Bhīṣmadeva. So they felt obliged. Of course, they knew everything, but externally they felt obligation: "Arjuna, I am getting money from Duryodhana. So in this point of danger, if I do not join him, it does not look well. I am getting financial maintenance."
Of course, Arjuna did not ask him. Arjuna was satisfied with Kṛṣṇa. That's all. Kṛṣṇa also divided Himself, because it is family quarrel. So He said, "I cannot take part with anyone, and even if I take part, side, of any of you, I shall not fight. Directly I shall not fight. I may be on your side or that side, but I'll not fight." Still, Arjuna was satisfied. So Kṛṣṇa, in order to satisfy Arjuna, that "I shall not fight, but I shall become your charioteer. I shall drive your chariot." So in this way the battle was arranged, and when Dhṛtarāṣṭra inquired, kim akurvata sañjaya (BG 1.1), "What did they do?" he said: "Sir, don't be disappointed. There was no compromise. Immediately your son, after seeing the military arrangement of the Pāṇḍavas, he was surprised, and immediately he went to Dronācārya"—he is the commander-in-chief appointed first—'What to do?' " Rājā vacanam abravīt (BG 1.2). Then he began to speak, to inform Dronācārya.