§ Of the Fifth Battle: Nirnaeth Arnoediad The Silmarillion

Now the phalanx of the guard of the King broke through the ranks of the Orcs, and Turgon hewed his way to the side of his brother; and it is told that the meeting of Turgon with Húrin, who stood beside Fingon, was glad in the midst of battle. Then hope was renewed in the hearts of the Elves; and in that very time, at the third hour of morning, the trumpets of Maedhros were heard at last coming up from the east, and the banners of the sons of Fëanor assailed the enemy in the rear. Some have said that even then the Eldar might have won the day, had all their hosts proved faithful; for the Orcs wavered, and their onslaught was stayed, and already some were turning to flight. But even as the vanguard of Maedhros came upon the Orcs, Morgoth loosed his last strength, and Angband was emptied. There came wolves, and wolfriders, and there came Balrogs, and dragons, and Glaurung father of dragons. The strength and terror of the Great Worm were now great indeed, and Elves and Men withered before him; and he came between the hosts of Maedhros and Fingon and swept them apart.