The Mantellian Separatist Movement arose on Ord Mantell during the period known as the Cold War, standing in opposition to the established Galactic Republic.
Following the signing of the Treaty of Coruscant, numerous planets chose to break away from the Galactic Republic, opting either to align themselves with the Sith Empire or to seek complete autonomy. The corrupt government then in power on Ord Mantell decided to maintain allegiance to the Republic. However, a significant portion of the planet's population yearned for their world to be independent. This desire for independence led to a civil war erupting on the planet, with the government receiving support from both the Republic and certain elements within the criminal underworld.
The Separatists on Ord Mantell created a network of clandestine bases. From these hidden locations, they initiated guerrilla warfare against both the Ord Mantell government and Republic assets. These attacks brought about widespread destruction across Ord Mantell's terrain and led to instability within the local governing bodies. One of the primary bases utilized by the separatists was a large volcano. Situated on the island of Avilatan, the volcano's core served as a Separatist stronghold, a location where meetings were held and separatist forces were coordinated. Separatist leaders frequently convened within this stronghold. Mannett Point island was another significant base. After invading the island, Separatist forces seized substantial quantities of Republic weaponry, which they then employed against government and Republic troops. These captured munitions included items such as small arms and rocket launchers.
The Separatist movement exerted control over substantial areas of Avilatan island. Separatist units engaged in combat to secure control of several villages located on the island, including Drelliad and the Talloran villages. Furthermore, the Avilatan Badlands became a highly contested region. Separatist forces asserted considerable influence over the Badlands, conducting raids on Republic convoys. The Separatists strategically utilized the Badlands as an ambush site, emplacing explosive devices along its terrain.
Investigations into the origins of the separatist movement revealed a shared source of funding with the Justicars' Brigade paramilitary organization—the reconstituted Sith Empire. The Sith Empire provided the Separatist cause with propaganda materials, weaponry, and financial assistance. The Sith Empire also operated a Listening Post on Ord Mantell. This post supplied the Separatists with intelligence regarding Republic troop movements.
As the civil war drew to a close, a faction of separatists, under the command of General Ortol, relocated to Cademimu V. Chornarov, the governor of Cademimu, declared the planet's independence from the Republic, with Ortol and his forces assisting him in gaining control of the planet and its missile defense systems. This action was met with resistance from the population of Cademimu. When both the Republic and the Empire intervened, the majority of the separatists, along with their commander, General Ortol, were killed.
By the year 3624 BBY, the separatists received support from the Hidden Chain, a renegade group of Mandalorians who opposed the faction led by Mandalore the Avenger.
The separatist military essentially encompassed the entire movement. It was well-organized and equipped, possessing the capability to deploy armor-piercing missiles and signal jammers on the battlefield. The military relied heavily on infantry militia, which was sometimes reinforced by heavy battle droid units ("liberation droids"). They employed a variety of tactics, ranging from large-scale assaults to guerrilla warfare, and were willing to inflict harm on civilians.
The separatist movement offered some opposition to the Republic Navy within the space surrounding Ord Mantell, deploying freighters and starfighters. These encounters almost brought an end to the career of one of the Republic's most formidable soldiers before it had truly begun.