J.R.R. Tolkien’s The Lord of the Rings was published as a complete three-volume set in 1955. The volumes appeared individually: The Fellowship of the Ring and The Two Towers were published in 1954, while The Return of the King followed in 1955.
Tolkien had written the work as one continuous story rather than as three separate novels. Publishing it in volumes was largely a practical decision connected with production costs and postwar paper shortages.
The final volume’s title caused Tolkien some concern because he thought it revealed too much about the story. Nevertheless, The Return of the King completed the published sequence and established the familiar three-volume format.
The 1955 date refers to completion of the original English publication sequence, not to the later popularity of the book or to its film adaptations. The three-volume structure became the standard way many readers encountered Tolkien’s epic.