As I discuss in this answer, the Adi Parva of the Mahabharata describes how Agni the fire god once needed to consume the Khandava forest in order to get over a malady, but Indra kept using rainstorms to extinguish the flames, because of his friendship with the Naga king Takshaka who lived there. So Agni consulted with Brahma, who told him the famous sages Nara and Narayana had reincarnated on the earth as Arjuna and Krishna. So he approached Arjuna and Krishna, who happened to be near the Khandava forest at the time, and asked them for help. They were happy to oblige, but they requested weapons that would be commensurate to the task of fighting Indra.
So Agni summoned Varuna to give them celestial weapons. Varuna gave Krishna the Sudarshana Chakra of Vishnu, and he gave Arjuna the famous Gandiva bow. But he also gave Arjuna one more thing, a celestial chariot that had belonged to Chandra the moon god:
Varuna ... gave a car furnished with celestial weapons and whose banner bore a large ape. Yoked unto that car were steeds white as silver of the fleecy clouds, and born in the region of the Gandharvas, and decked with golden harness, and resembling in fleetness the wind or the mind. And it was equipped with implement of war, and was incapable of being vanquished by the celestials or the Asuras. Its splendour was great and the sounds of its wheels was tremendous. It delighted the heart of every creature that looked at it. It had been made by Viswakarman, the architect of the universe and one of the lords of creation, after severe ascetic meditation. Its splendour, like that of the sun, was so great that no one could gaze at it. It was the very car from which the lord Soma [Chandra] had vanquished the Danavas [Asuras]. Resplendent with beauty, it looked like an evening cloud reflecting the effulgence of the setting sun.
My question is, when did Chandra use this chariot to defeat the Asuras (demons)? The only war between the gods and the Asuras I'm aware of where Chandra played a prominent role is the famous Tarakamaya war, but Chandra was on the Asura side during that war. As I discuss in this question, the Tarakamaya war was started when Chandra kidnapped Tara, the wife of Brihaspati guru of the gods, so the gods fought Chandra on behalf of their guru, while the Asuras took Chandra's side.
So what is the story of Chandra's victory against the Asuras where he rode the chariot later given to Arjuna?