Mantooine was a celestial body located in the Atrivis sector, serving as the location for an Imperial garrison. As the sector saw the rise of an armed rebellion, the Liberators, a resistance movement based on Mantooine, successfully took control of the local garrison, only to be subsequently defeated by the forces of the Imperial Navy.
Within the Atrivis system of the Atrivis sector, Mantooine was a planet located where the Outer Rim Territories and the New Territories intersected.
Yoda, in his capacity as Master, once journeyed with his Padawan, Dooku, to Mantooine, an event that Dooku later documented within his personal journal.
During the Galactic Empire's reign, Mantooine became the site of an Imperial garrison. However, an armed rebellion emerged against the Empire in the Atrivis sector, with Mantooine hosting its own resistance faction called the Liberators. The sector was also home to another rebel group, the Atrivis Resistance Group, based at Generis Station, though they operated independently from the Liberators. In 5 BBY, the Liberators seized the Imperial garrison on Mantooine, but the Imperial Navy quickly suppressed them. News reports covered the events that transpired on Mantooine. Following the Liberators' downfall, Travia Chan, who led the Atrivis Resistance Group, was prompted to agree to form a partnership with a larger organized rebellion against the Empire, secretly led by Senator Mon Mothma, during that same year.
To commemorate the Liberators' defeat on Mantooine, Mothma's rebellion created the Mantooine Medallion, an award bestowed by high command members upon rebel personnel who displayed extraordinary bravery in the face of enemy forces. Initially, the medallion was awarded to surviving members of the Liberators after their cell's defeat. It later became the fourth highest honor awarded by the high command, given to individuals who made exceptional contributions to the rebel military's readiness.
By 2 BBY, Mantooine had evolved into a regional headquarters and operational hub for Mothma's rebellion. This designation was reflected on a map of the galaxy that identified rebel safe worlds, starfighter hubs at level five or higher, regional headquarters and operations sectors, and hidden deep space caches. In that same year, the rebellion underwent formalization, becoming the Rebel Alliance. By 1 BBY, General Antoc Merrick facilitated the use of the rebel UT-60D U-wing starfighter/support craft as a troop transport on Mantooine. Merrick detailed the U-wing's use on Mantooine in a report to Mothma, advocating for its broader adoption as a multi-role starship. This report, alongside the map of rebel locations, was subsequently incorporated into an archive of non-electronic documents called The Rebel Files by archivist Hendri Underholt.
The first mention of Mantooine was in Lead by Example, a canon sourcebook released by Fantasy Flight Games in 2016.