War of Wrath

The War of Wrath, or the Great Battle, a key plot development in J.R.R. Tolkien's legendarium, is the final war against Morgoth at the end of the First Age.

Elrond, at his Council, makes comparison to the Last Alliance of Elves and Men of the Second Age in The Lord of the Rings saying,

In the Tale of the Years it is called the Great Battle and the army, the Host of Valinor. The best known and most poetical account is in The Silmarillion, itself closely drawn from the earlier Quenta Silmarillion. The most detailed account of the course of the war is in The Later Annals of Beleriand. Other accounts and fragmentary details about the war are scattered, appearing in the earliest versions of the legendarium.

The experience of distance to the War of Wrath is greatest in Lord of the Rings, drawing nearer to it in The Silmarillion, closer still in the Annals and Quentas of the History of Middle-earth and closest, in aspects, in The Lost Tales.

The Silmarillion account

As it is told in The Silmarillion, by the end of the five centuries after the rising of the sun, Morgoth had defeated all who opposed him and become mighty and uncontested in Middle-earth. The mariner Eärendil, by the light of the Silmaril on his brow, searches and comes to Valinor, on behalf of the two kindreds (that of Elves and Men), asking the Valar to pardon and aid the enthralled Elves and Men of Middle-earth.