Ulfang the Black
Ulfast	Ulwarth	Uldor the Accursed

At the time of the Dagor Bragollach, the Men of the Edain had fought faithfully beside the Eldar for generations, and after that disastrous battle, many of the Elves sought to bolster their forces with newly arrived Men from beyond the Blue Mountains. Among these was Ulfang, from one of the many houses of the Swarthy Men. He joined himself to the people of Caranthir, fourth son of Fëanor, with his three sons Ulfast, Ulwarth and Uldor.

These Men were secretly in league with Morgoth, and had come across the Mountains at his summons. Over the years that followed, Ulfang's son Uldor¹ worked to undermine the Sons of Fëanor, earning him the title of 'the Accursed'. He secretly brought further forces of Men in his service across Ered Luin, and when the time came for the great battle that would be known as the Nirnaeth Arnoediad, he made false reports of attacks from Angband, thus causing Maedhros' eastern force to be late into the field.

As the battle raged, Uldor and his brothers switched sides, and the Men they had hidden in the eastern hills joined on the side of Morgoth. The Sons of Fëanor were revenged on Uldor, as Maglor was able to slay him on the field, but the battle was a disastrous loss for the Eldar and a victory of Morgoth. Indeed, it's said that it was the treachery of Men - and specifically of Uldor the Accursed - that turned the tide of battle in Morgoth's favour.

After Uldor's death his people remained in the service of Morgoth, and could even be found fighting for the Dark Lord in the War of Wrath that brought the First Age to a close. So Uldor's name was remembered as Accursed by the Elves long after the end of that Age.