Originally posted by: .Vrish.
Latter did happen, but the former was a BRC invention. There was no conference b/w Duryodhan, Ashwatthama & Karna. In fact, day 17 was when Dushashan, then Vrishasena & then Karna got killed. Before Dushashan, a number of Kaurava warriors, including Karna's son Prasena, were killed, while Yudisthir was defeated and sent back to his camp by Karna, which caused him to be humiliated and almost get into a fight w/ Arjun
Am not sure which one was BRC invention. But the below did happen before Arjun and Karna fought on the 17th day.
http://www.sacred-texts.com/hin/m08/m08088.htm
Then Drona's son, catching hold of Duryodhana's hand, and adopting a soothing tone, addressed thy son, saying, "Be gratified, O Duryodhana! Make peace with the Pandavas. There is no need for quarrel. Fie on war! The preceptor, conversant with the mightiest of weapons and like unto Brahma itself, hath been slain. Other bulls among men, headed by Bhishma, have also been slain. As regards myself, I am unslayable, as also my maternal uncle. Rule the kingdom for ever, (sharing it) with the sons of Pandu. Dissuaded by me, Dhananjaya will abstain. Janardana also doth not desire hostilities. Yudhishthira is always engaged in the good of all creatures. Vrikodara is obedient to him. So also are the twins. Peace being made between thee and the Parthas, all creatures will be benefited, through, as it would seem, thy desire. Let the kings that are still alive go back to their homes. Let the troops abstain from hostilities. If thou dost not listen to my words, O king, struck by foes in battle, thou wilt have to burn with grief. Thou hast beheld, as well as the universe, what has been achieved by the single-handed Arjuna decked with diadem and garlands. The slayer of Vala himself could not achieve its like, nor the Destroyer, nor Prachetas, nor the illustrious king of the Yakshas. Dhananjaya, as regards his merits, is even much greater than that. He will never transgress whatever I say unto him. He will always follow thee. Be thou gratified, O king, for the benefit of the universe. Thou always honourest me greatly. I, too, bear a great friendship for thee. It is for this that I say so unto thee. I shall dissuade Karna also, provided thou art inclined to peace. Discerning persons say that there are four kinds of friends, viz., those that are naturally so, those that are made so by conciliation, those that become so through wealth, and lastly those brought under subjection by the exercise of power. All these elements are owned by thee with regard to the sons of Pandu. The Pandavas, O hero, are naturally thy friends. Obtain them again as friends for certain by conciliation. If upon thyself being gratified, they agree to become friends, do thou, O king of kings, act in that way."