The ''Invincible Reason'' was a [[Battleship]] of the [[Dark Angels]] [[Space Marine Legion|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 [[Thrasmas Thramas Crusade]].{{Fn|1}}