The Invincible Reason was a Gloriana Class Battleship of the Dark Angels Legion during the Great Crusade and Horus Heresy. The personal ship of Primarch Lion El'Jonson, the Invincible Reason led the Dark Angels effort in the Battle of Diamat and the Thramas Crusade. Following the Thramas ambush against the Night Lords, Konrad Curze became stranded on board the Invincible Reason for a time. However the Night Haunter found ample hiding places on the immense vessel, and terrorized the bowels of the ship despite repeated Dark Angels search parties. He eventually left the vessel when the Lion led the Dark Angels fleet to Macragge.
- 1: The Lion (Novella) by Gav Thorpe, - The Primarchs (Anthology), pg. 225
- 2: The Unremembered Empire (Novel)