The Dagor Dagorath (Sindarin for Battle of Battles) is a fictional battle described in the legendarium of J. R. R. Tolkien. As Tolkien's 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 simply "The End". As Tolkien originally wrote it, The Silmarillion ends with a prophecy by Mandos about the Dagor Dagorath. The published Silmarillion ends instead with the recounting of the voyage of Eärendil the Mariner, but this is due to an editorial decision by Christopher Tolkien. However, references to the final battle remain in the published Silmarillion, such as a statement at the end of the Akallabêth that Ar-Pharazôn and his mortal warriors who had set foot on Aman were buried by falling hills, imprisoned in the Caves of the Forgotten until the "Last Battle and Day of Doom". Christopher Tolkien sees the account as similar to the Nordic legend of Ragnarök and J. R. R. Tolkien also made this connection in some of his letters.
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... This might be a reference to the times after Dagor Dagorath ... the Second Prophecy 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 ... Manwë will not descend from the Mountain until Dagor Dagorath, and the coming of the End, when Melkor returns ...