As the forces of Nargothrond, inspired by Turin, became increasingly assertive, Glaurung launched an attack on the previously hidden city, using a bridge built to enable the city's elves to go to war. He routed and burned the city, slaying many of its defenders, including Gwindor.
He hypnotised Turin, sending him on a wild goose chase to Mithrim, and later Nienor, who developed complete amnesia as a result (hence her marriage to her brother Turin).
Slain by Turin as he came forth against a host from Brethil. Turin attacked his vulnerable underside, mortally wounding the dragon.