Which Tolkien work was first published in three volumes from 1954 to 1955?

The Lord of the Rings was first published in three volumes from 1954 to 1955.

The volumes were The Fellowship of the Ring, published in July 1954; The Two Towers, published in November 1954; and The Return of the King, published in October 1955. Tolkien conceived the work as a single novel, but publication in multiple volumes reflected practical and economic considerations.

The story follows Frodo Baggins and the Fellowship as they attempt to destroy the One Ring in Mount Doom. It is set in the Third Age of Tolkien’s imagined history and expands many themes and peoples first introduced in The Hobbit.

The three volumes are sometimes called a trilogy, but Tolkien regarded them as parts of one work rather than three independent novels. The title The Return of the King was chosen despite Tolkien’s concern that it might reveal too much about the ending.