What is dagorath?

Some articles on dagorath:

Dagor Dagorath - Development and References in Tolkien's Works
... This might be a reference to the times after Dagor Dagorath ... explicitly states that the Elves and Valar shall be renewed after Dagor Dagorath and that the fate of Men is unknown, The Silmarillion states that Men will participate in singing the ... Manwë will not descend from the Mountain until Dagor Dagorath, and the coming of the End, when Melkor returns ...
Dagor Dagorath
... The Dagor Dagorath (Sindarin for Battle of Battles) is a fictional battle described in the legendarium of J ... works were conceived as a fictional "forgotten history" of the world, the Dagor Dagorath represents the coming End of the World, and is often referred to as ... As Tolkien originally wrote it, The Silmarillion ends with a prophecy by Mandos about the Dagor Dagorath ...