In this add-on for The Lord of the Rings: The Battle for Middle-Earth II it is your goal to lead the great armies of the Witch-King called the Angmar to victory. But there are also other mentionable additions and changes which come with this add-on: All six factions from the main game now have access to new units and heroes like Prince Brand a Dwarven captain or the Uruk Deathbringers on the side of Isengard which are powerful two-handed swords-fighters.

The campaign allows the player to command the army of Angmar from its foundation and early attacks against Arnor, to the destruction of Arnor at the battle of Fornost. The story for The Rise of the Witch-king draws a great deal upon the Appendices at the end of The Return of the King to form a basis for the conflict between Arnor and Angmar. Many of the notes that Tolkien made regarding the war are used as missions in the games campaign and epilogue. Although the game closely follows Tolkien's writing, some events are modified to suit the gameplay (such as the palantír of Amon Sûl being destroyed rather than brought to safety at Fornost), or are omitted altogether (such as the flight of King Arvedui from the defeat at Fornost).