Gwindor was credited with beginning the Nírnaeth Arnoediad at the sight of his brother Gelmir's brutal murder at the hands of the orcs, he charged the hosts of Morgoth on the plains of Anfauglith without any command from any others. It is said that Morgoth trembled before his ire as he approached, but he was ultimately captured when Morgoth's reserves were set forth from the fortress and the Armies of men and elves were overrun. He was enslaved and became a thrall of Angband for fourteen years.
Gwindor escaped Angband, but his hand was chopped off while fighting one of the orc guards. The injury devastated Gwindor and he fell into despair in the wilderness and nearly died of his wound. He was rescued by Beleg Cúthalion and his will to live returned. He later helped Beleg free Túrin Turambar and, after Beleg's tragic and accidental death, Gwindor found himself trying to rouse Turin as Beleg had roused Gwindor. He brought him to Nargothrond. He counselled against Túrin's policy of open warfare upon Morgoth's forces, but was ignored. He loved the elf, Finduila Faelivrin, but felt unworthy of her love. He grew Jealous of Turin since she loved him more and felt Turin had gained respect from the council at his expense. He warned Finduilas that Turin was cursed and would bring only doom to the people he loved. He was slain alongside Orodreth in the Battle of Tumhalad.