The Nirnaeth Arnoediad or Battle of Unnumbered Tears was the disastrous Fifth Battle in the Wars of Beleriand. Its name was taken from the first words of the Doom of Mandos: "Tears unnumbered ye shall shed..."
Under the Union of Maedhros all the Elves of Beleriand, as well as the Edain, Dwarves, and the newly arrived Easterlings were invited to combine in arms and fight Morgoth. The Union first cleared Beleriand and Dorthonion of Orcs and then gathered to assault Thangorodrim.
The plan was for Maedhros's host in the east to assault and draw out the army of Angband, after which Fingon's host would attack from the Ered Wethrin, taking the offensive in the west, crushing Morgoth's forces between them.
Under Fingon in the west were gathered the Elves and Men of Hithlum, the Elves of the Falas, the Haladin of Brethil and the companies sent from Nargothrond and the two elf-captains of Doriath, Beleg and Mablung.
Because of the evil deeds of Celegorm and Curufin, two of Maedhros's brothers, Nargothrond would send only a small company of Elves under Gwindor. From Doriath, where Thingol had sworn never to fight beside any son of Fëanor, came only Mablung and Beleg, who did not wish to remain behind. However, Turgon unexpectedly came forth with over ten thousand Elves from Gondolin, doubling the force of the west.
But Morgoth through his spies had learned of the battle plan, and his spy Ulfang, who betrayed the Noldor, delayed Maedhros' attack. A small host of Orcs sallied forth from Angband to provoke the Western host to attack. Within sight of the Ered Wethrin, Gwindor's brother Gelmir, captured during the Dagor Bragollach, was brought forth, and brutally slain. Enraged, Gwindor broke ranks and charged along with his men. From their hidden positions in the eastern hills, Fingon's forces suddenly charged along with them. The Orc host was taken by surprise and swiftly defeated, and the sudden charge of Fingon's army nearly foiled Morgoth's plans; the forces of Gwindor and Fingon pushed forth, reaching Angband itself.
Morgoth shook upon this throne as Gwindor's company pounded at his gates above. They burst through, and slew the guards on the steps of Angband itself, though Morgoth had trapped them. They were then ambushed with hidden forces set about Angband; all of Gwindor's company was slain and Gwindor himself was captured. From clandestine gates around Angband, thousands of Orcs erupted suddenly, repulsing the host of Fingon from the walls. The Elven army was driven back in great slaughter, and many Haladin fell fighting in the rearguard.
Turgon, who had withheld his host from the reckless charge, now came upon the Orc host. The phalanx of Turgon broke through the Angband lines, and met with the guard of Fingon.
Finally, Maedhros arrived, but before he could make junction with Fingon and Turgon, Glaurung the dragon and Gothmog lord of Balrogs intercepted him. Union forces could yet have prevailed, but Uldor, son of Ulfang and a traitor, turned ranks and attacked Maedhros in the rear, while more of his kin came down from the mountains and attacked from the east. Maglor slew Uldor in single combat, but could not turn the tide of the battle. Under assault from three sides, the eastern host was scattered, and only the valour of the Dwarves of Belegost helped them escape, as their lord Azaghâl and his forces held off Glaurung, allowing the sons of Fëanor to escape to Ossiriand.
Azaghâl and his army fought with fierce iron masks on, and they were able to resist the fire far better than any Elf or Man. Then Glaurung trampled Azaghâl beneath his feet, but Azaghâl ran a dagger through Glaurung's stomach, and the dragon fled in pain. Many of Morgoth's forces retreated with him. In a solemn ceremony, the Dwarves picked up their fallen leader, abandoning the battle, and marched him home in a great procession. Their wrath was so great that none troubled them.
All this had not helped the western host, who were attacked by many Orcs under Gothmog. Gothmog cut a path to Fingon and fought him in single combat. Fingon fell under his might, and Húrin begged Turgon to retreat back to Gondolin. Huor and Húrin and the remaining Men of Dor-lómin formed a living wall across the Fen of Serech, buying time for Turgon to escape with most of the surviving Elves of the north. Acting as a rearguard, these Men were almost all slain – Huor fell when his eye was pierced by a poisoned arrow. His brother Húrin fought ferociously to buy his allies time to escape, fighting until his axe withered away. Morgoth had ordered him to be taken alive, however; he killed no fewer than seventy Orcs and Trolls before he became pinned under their corpses, and was later taken prisoner by Gothmog.