Originally Posted by chapter 19, The Silm

“The hunters turned east and north, and following the course of the river they came at last upon Carcharoth the Wolf in a dark valley, down the northern side whereof Esgalduin fell in a torrent over steep falls. At the foot of the falls Carcharoth drank to ease his consuming thirst, and he howled, and thus they were aware of him. But he, espying their approach, rushed not suddenly to attack them. It may be that the devil’s cunning of his heart awoke, being for a moment eased of his pain by the sweet waters of Esgalduin; and even as they rode towards him he slunk aside into a deep brake, and there lay hid. But they set a guard about all that place, and waited, and the shadows grew long in the forest.
Beren stood beside Thingol, and suddenly they were aware that Huan had left their side. Then a great baying awoke in the thicket; for Huan becoming impatient and desiring to look upon this wolf had gone in alone to dislodge him. But Carcharoth avoided him, and bursting from the thorns leaped suddenly upon Thingol. Swiftly Beren strode before him with a spear, but Carcharoth swept it aside and felled him, biting at his breast. In that moment Huan leaped from the thicket upon the back of the Wolf, and they fell together fighting bitterly; and no battle of wolf and hound has been like to it, for in the baying of Huan was heard the voice of the horns of Oromë and the wrath of the Valar, but in the howls of Carcharoth was the hate of Morgoth and malice crueller than teeth of steel; and the rocks were rent by their clamour and fell from on high and choked the falls of Esgalduin. There they fought to the death; but Thingol gave no heed, for he knelt by Beren, seeing that he was sorely hurt.
Huan in that hour slew Carcharoth; but there in the woven woods of Doriath his own doom long spoken was fulfilled, and he was wounded mortally, and the venom of Morgoth entered into him. Then he came, and falling beside Beren spoke for the third time with words; and he bade Beren farewell before he died. Beren spoke not, but laid his hand upon the head of the hound, and so they parted.”