The followers and apprentices of Xendor, the Jedi Renunciate and exile from the Kashi Mer Dynasty, adopted the title Legions of Lettow. As one of the Jedi Order's initial breakaway groups, these Legions ultimately faced defeat in a brutal war against their Jedi counterparts.
In the early days of the Jedi Order, Xendor, an exile of the Kashi Mer, pursued his studies on Ossus, a fortress world that served as the Jedi's stronghold. Ossus fostered a culture deeply committed to exploring the Force, particularly its light side aspect, known as the Ashla. Xendor, a well-regarded Jedi Knight, openly challenged the Order's perspective on the Force, which he deemed "exclusionary." Among his closest confidantes was Arden Lyn, a Follower and Steel Hand of Palawa; the two shared their diverging philosophies in secret from the Jedi High Council, eventually becoming romantically involved.
No longer able to contain his discontent, Xendor approached the High Council, seeking their approval to establish a new Jedi academy away from Ossus. This academy would focus on the darker aspects of the Force, known as the Bogan. Upon the Council's refusal, Xendor quietly departed from the Order and journeyed to Lettow, where he founded an academy dedicated to the teachings of the Bogan. Drawing inspiration from Force traditions such as the Order of Dai Bendu, the Followers of Palawa, the Kashi Mer Guardians of Breath, the Baran Do, and the Chatos Academy, Xendor's academy initially attracted a small number of adherents, but quickly grew in popularity. Xendor and his followers embraced the dark side of the Force, rejecting the principles of order and structure, and reveling in their freedom by indulging in their passions and emotions and experiencing the power of the dark side. These acolytes subsequently named their new organization the Legions of Lettow, anticipating a future conflict with the Jedi High Council to defend their beliefs.
Within the academy, the Legionnaires participated in initiation rituals mirroring those of the Jedi Order. For instance, the practice of forging Force-imbued blades was adopted from ancient Tythonese traditions. Initiates underwent a rigorous ritual in the academy's furnaces, shaping high-carbon steel while merging the blade's molecular structure with that of an energy crystal, effectively uniting the two. Using the furnace-forged steel, the Legionnaires embraced the ancient Jar'Kai combat style, renaming it Niman in honor of the triumvirate of Kashi gods.
Around 24,500 BBY, open warfare erupted between the Legions and the Jedi Order. According to the Jedi Order's records and some historians, General Xendor and his Legionnaires initiated the conflict by attacking the Jedi. However, other accounts suggest that the Jedi Council declared war on the Dark Legions. The most comprehensive account, provided by Imperial Grand Inquistitor Laddinare Torbin based on Arden Lyn's recollections, indicates that the Jedi Order mobilized an army first. Consequently, a reluctant Xendor assumed the title of general and launched a direct assault on Ossus to avert further bloodshed. Nevertheless, during the battle, Xendor's forces were repelled, compelling them to deploy troops across multiple fronts as the Order pushed the Legionnaires toward the galaxy's core. Xendor then attempted to alert the Galactic Republic that the Jedi Order sought to seize power under the pretense of protection, but his warnings were dismissed, and he was branded a warlord by the Republic.
The conflict between the Jedi Order and the Legions of Lettow intensified on Chandrila, Metellos, Brentaal IV and Coruscant until the Jedi leader, Awdrysta Pina engaged Xendor in direct battle on Columus. Master Pina, known as the Green Blade, and his Jedi Knights skillfully isolated Xendor's vanguard from the main body of his army using a strong Force meld – a technique rejected by the Legionnaires due to their belief that it compromised their individuality. After defeating formidable warriors such as Sethul Asaiage and Tun Bohoi, Pina ultimately confronted Xendor in a duel and killed him in hand-to-hand combat.
Following Xendor's death, Arden Lyn assumed command of the remaining Legionnaires on Lettow. As Pina's forces took over the academy, Lyn and her followers resisted the Jedi until the Legionnaires managed to escape Republic space. Separating from the other survivors, Lyn attempted to hide beyond Kitel Phard, but Master Pina pursued her, eventually cornering her on Irkalla. There, Lyn utilized a Kashi Mer talisman given to her by Xendor to channel her rage and grief over his loss, shattering Pina's blade and sending the fragments through his body. As he lay dying, Pina expended his final energy to attack Lyn with the Morichro technique, stopping her heart and nearly killing her.
In the centuries that followed Xendor's departure from the Order, the Jedi who would later become known as the Dark Jedi Exiles of the Hundred-Year Darkness considered themselves to be the inheritors of the Legion of Lettow's legacy. Banished to the Unknown Regions, the Exiles established the Sith Empire with a philosophy centered on the dark side of the Force.
A record of the final battle on Columus survived the conflict and was acquired by the Jedi Order. Known as the Columus Data Card, the files consisted of audio recordings made by Padawan Danzigorro Potts. In his dying moments, Potts recounted the final battle, describing the deaths of Xendor and other former Jedi, including his own master Jook-jook H'broozin and friends Blendri and Cuthallox.
Millennia later, the phrase "Minions of Xendor!" remained a common curse among smugglers.
In George Lucas' initial draft of the original script for A New Hope, originally titled "The Star Wars," the "Legions of Lettow" served as the name for the Knights of Sith, with members simply referred to as "Lettow." This early script bears little resemblance to the final script used for the film. The Power of the Jedi Sourcebook later revealed that the "Legions of Lettow" were a historical adversary of the Jedi Order, and The New Essential Chronology identified Xendor's followers as the Legions of Lettow.