The War of the Ring is the eighth volume in the History of Middle-earth se covers The Lord of the Rings through the Battle of the Hornburg, the sack of Isengard, Frodo and Sam's journey through the pass of Cirith Ungol, the War of the Ring in Gondor, and ends with Gandalf's encounter with the Mouth of Sauron at the Black Gate.

The inscription in Book VIII reads: "In the War of the Ring is traced the story of the history at Helm's Deep and the drowning of Isengard by the Ents, then is told of the journey of Frodo with Samwise and Gollum to the Morannon, of the meeting with Faramir and the stairs of Cirith Ungol, of the Battle of the Pelennor Fields and of the coming of Aragorn in the fleet of Umbar."