Eärendil and Thorondor are confronted by Ancalagon in an aerial battle in which the dragon is shot down, bringing down the peaks of Thangorodrim and defeating its master.
[1] In his English-language version of the Quenta, Tolkien translates Ancalagon as Anddraca, from and-, an oppositional prefix, and draca "dragon".
Sensing that victory was slipping from his grasp, he called in his reserve forces, the first winged dragons, led by Ancalagon the Black.
So terrible was the force of the attack that "the armies of the Valar retreated before the thunder, lightning and hurricane of flames that preceded the dragons".
Ancalagon, shot out of the sky, falls on the peaks of Thangorodrim, causing their destruction and ending the War of the Great Wrath.
[7] In later versions, notably in the 1969 essay The Problem of Ros, Tolkien suggests that Ancalagon may have been felled by Túrin, who returned after its death from the outer void of Arda to fight in the Final Battle, according to a prophecy of Andreth.
[12] According to Kristin Larsen, this confrontation is a euhemeric rendering of a meteor shower falling on Venus, the star corresponding to Eärendil in Tolkien's mythology.