The Sixth Line constituted a combative group within the Jedi Order, operating throughout the Galactic War that pitted the Galactic Republic against the Sith Empire. Their designation originated from the "sixth line" they appended to the established Jedi Code: "There is no contemplation, there is only duty." Under the guidance of Jedi Master Surro and various other Masters, the Sixth Line functioned as a rapid response force for the Republic, generally acting on the instructions of the Republic Strategic Information Service. Following the unsuccessful defense of the Balmorran Arms Factory by Grand Marshal Cheketta, the Sixth Line was dispatched to the planet Balmorra.
Subsequently, as the war progressed, Agent Theron Shan uncovered the presence of the former Sith Emperor Vitiate on the world of Ziost; he then summoned the Sixth Line to Ziost. However, Vitiate seized control of the entire Sixth Line, along with the planet's inhabitants. In the devastating Invasion of Ziost, the overwhelming number of the Sixth Line perished.
Many years later, during the final confrontation with Tenebrae, the spirits of Sixth Line members were among those observing his ultimate demise.