Nirnaeth Arnoediad: Morgoth's Greatest Victory | Tolkien Explained

In midsummer of the year 472 of the First Age, the free peoples of Beleriand gathered for their boldest gamble against Morgoth. The Union of Maedhros — Noldor, Sindar, the Men of the Edain, Easterlings, and the Dwarves of Belegost — marched to end the Dark Lord in a single hammer-and-anvil stroke. It ended in the greatest catastrophe of the age: the Battle of Unnumbered Tears, the Nirnaeth Arnoediad. A planted lie and a moment of grief broke the plan before it could strike. Morgoth unleashed Glaurung and his Balrogs; the traitor Ulfang turned upon the host from the rear; High King Fingon fell to Gothmog, his banner trodden in the dust. Only Húrin remained, crying "Aurë entuluva" — day shall come again — seventy times before his capture. From this ruin rose the green grass of the Hill of Slain, Huor's prophecy of Eärendil, and the seed of every rescue still to come.