Which 1977 book did Christopher Tolkien edit and publish four years after his father’s death?

The 1977 book Christopher Tolkien edited and published four years after his father’s death was The Silmarillion. J.R.R. Tolkien died in 1973, and Christopher prepared the unfinished materials for publication.

The book presents a mythological history of Tolkien’s world, beginning with creation and continuing through the First Age. It includes accounts of the Valar, the Elves, the Silmarils, and the wars against Morgoth, the earlier great enemy of Arda.

The Silmarillion was not completed as a single final manuscript in the way The Hobbit was. Christopher Tolkien had to compare drafts, versions, notes, and revisions, then create a coherent published form while explaining editorial decisions.

Its title refers especially to the Silmarils, three jewels made by Fëanor. The book is therefore not simply a prequel to The Lord of the Rings; it is a collection shaped as a mythology and history of the wider world. Unfinished Tales appeared later, in 1980.