The battle of Helm’s Deep appears in J.R.R. Tolkien’s The Two Towers.
The battle is part of the novel’s third book, “The Treason of Isengard,” and takes place in the fortress of the Hornburg. King Théoden’s forces defend Rohan against the army sent by Saruman, while Aragorn, Legolas, and Gimli fight alongside the Rohirrim.
The Two Towers is the second published volume of The Lord of the Rings. It also follows Frodo and Sam as they continue toward Mordor with Gollum as their guide. The title refers to two important strongholds, commonly identified as Orthanc in Isengard and Minas Morgul near Mordor.
Readers sometimes associate Helm’s Deep with The Return of the King because the film adaptations combine and rearrange events. In Tolkien’s novel, however, the battle is firmly located in The Two Towers, before the final volume’s major battles and conclusion.