In J. R. R. Tolkien's fictional Middle-earth, the Dagor Bragollach was the fourth battle of the Wars of Beleriand, known as the Battle of Sudden Flame.

It began when Morgoth broke the Siege of Angband, which had held for four hundred years. On a winter's night, Morgoth sent out rivers of flame, consuming Ard-galen, which was renamed Anfauglith. Many elves perished as they fled from these flames, from the fire and the smoke. His armies of Balrogs and Orcs, led by Glaurung first of the Foalókë, overran the highlands of Dorthonion, and slew Angrod and Aegnor. Maglor's horsemen were burnt alive on the plain of Lothlann, and Maglor's Gap was taken, giving Morgoth an entry into Beleriand itself. Maglor retreated with heavy losses to Himring, where he helped defend the city of Maedhros.

The Pass of Aglon was also breached, and Celegorm and Curufin fled north of Doriath to Nargothrond. Morgoth's Orcs took the mountain forsts of Mount Rerir, and defiled Lake Helevorn , scattering south through Thargelion into East Beleriand. Caranthir fled to Amon Ereb, where he and Amrod built defenses. From there they slowly freed East Beleriand of the Orcs, while Maglor and Maedhros held the northern border.

Minas Tirith in the Pass of Sirion in the West under Orodreth held, and Orodreth's uncle and Lord Finrod Felagund came north from Nargothrond with a large army. However, they were ambushed by a large army of Morgoth's forces at the Fen of Serech. The Noldor now found themselves trapped, and Finrod would have been killed but for a sortie by Barahir, who descended from Dorthonion and rescued the Elven lord. It was this deed which later earned Barahir the ring of Finrod which would become known as the Ring of Barahir.

Finrod and his folk fled south to Nargothrond, while Barahir continued defending Dorthonion. The mountain forts of the Ered Wethrin around Hithlum also held, although barely.

Thus the Siege was broken, the sons of Fëanor scattered, and the forces of Morgoth roamed at will throughout the north.

When Fingolfin, the High King of the Noldor, learned of the heavy casualties of so many Noldor, he rode in anger across the dust of Anfauglith and challenged Morgoth to single combat. At the doors of Angband itself, they fought a great duel. Fingolfin's sword, Ringil, wounded Morgoth eight times. Yet, he was felled by Morgoth's hammer, Grond, and slain by Morgoth's mighty foot.