Ossus Project The Ossus Project was an epic undertaking , coordinated from the planet Ossus , and overseen by Kol Skywalker of the New Jedi Order and Nei Rin of the Yuuzhan Vong Shaper caste . The project ' s purpose was to heal and revive over a hundred worlds across the galaxy that had been devastated in the past , and some even hoped it would permanently end problems that had long afflicted the galaxy , such as hunger and war . It was sabotaged by Darth Maladi and Zenoc Quah to cause massive suffering , and the Council of Moffs framed the sabotage on the Yuuzhan Vong , creating a galaxy - spanning conflict that would become known as the Sith – Imperial War . History . Success on Ossus . The Galactic Alliance gradually finished rebuilding itself a few years later , but would never be the same as the pre - invasion New Republic . In 122 ABY , as part of a move to improve relations between the Yuuzhan Vong and the rest of the galaxy , the New Jedi Order permitted Yuuzhan Vong Shapers , under Master Shaper Nei Rin , to use a desolate part of Ossus , one of the Jedi Order ' s most ancient strongholds , as a testing area . The intent of those who supported the project — such as Jedi Master Kol Skywalker , a leading member of the Jedi Council — was to see if Vong terraform ing techniques , such as those that had once transformed Coruscant into the species ' s temporary homeworld of Yuuzhan ' tar ( 27 - 29 ABY ) , could restore the world that had been left barren and devastated . The experiment appeared to work perfectly , returning Ossus to vibrant life again . When the Jedi showed the results to the outside galaxy , the response was tremendous as other worlds gained their chance to restore planets devastated by the Yuuzhan Vong War . One hundred devastated planets were selected for potential terraforming . Yuuzhan Vong Shapers , overseen by Jedi escorts , set to work , and the initial results were wondrous to behold , exemplified on Wayland . Sowing seeds of hatred . This success was short - lived , however . Agents from the One Sith , including Sith Lady Darth Maladi and Yuuzhan Vong shaper Zenoc Quah , secretly sabotaged the terraforming processes under the orders of the cult ' s leader Darth Krayt . Soon on Wayland , the vegetation of the terraformed world underwent mutations of a kind not seen since the Vong forcibly took populations as slaves for shaping . Painful bony growths sprouted from the skin of the natives in a plague that affected all the terraformed worlds , bringing the project to a catastrophic end . The Vong were shocked ; none of the preliminary experiments on Ossus had shown any of the later mutations . Master Shaper Rin made it her mission to learn what had happened , and why . The Jedi suspected sabotage at once , but had no idea who was responsible . Many accused the Yuuzhan Vong as much animosity still existed towards the authors of one of the most destructive wars the Galaxy had ever seen . The Sith knew the lingering scars of the Vong War would cause people to suspect them of such heinous acts . The Jedi , maintaining the innocence of the Vong , convinced the Galactic Alliance to support the Vong against bigotry and unbiased domestic criticism . This angered many Alliance worlds and as a result many withdrew from the Galactic Alliance or declared their neutrality . The Empire meanwhile , seized on the opportunity opened by the loss of confidence in the Galactic Alliance . With the Pellaeon – Gavrisom Treaty that ended its war against the former Rebellion came in 19 ABY , the Imperial Remnant had ended its hostilities to New Republic as a neutral faction , and the Vong invasion had brought them together as allies to the New Republic and its successor . But its nominal government , the members of the Moff Council , still had many hard - line holdovers to the old ways who wanted to restore the Empire to primacy as the dominant galactic power , peace treaty or not . Now they called for retribution and , invoking the Treaty of Anaxes , they declared war on the Galactic Alliance . The peace that so many had fought and died for in decades past was undone in one swift stroke , all thanks to the resurgent Sith Order . Fearing what could ultimately happen , the Jedi High Council ordered the creation of the Hidden Temple at the start of hostilities , its location chosen by Nat Skywalker so the Jedi could have a refuge . The war . From the beginning of the war the Alliance was handicapped . Its defense of the Yuuzhan Vong had alienated numerous member worlds , whose populations still nursed bitter memories of the Vong invasion , and many of them refused to support the Alliance . Soon , the Alliance found itself facing a secession movement as well as general war . The Empire used this to its advantage , luring some of these disaffected worlds into the Imperial camp and weakening the entire Alliance government . Other worlds declared neutrality . Thus the war began with the Empire possessing all the advantages . But Emperor Roan Fel himself was less than enthusiastic ; he ' d only reluctantly declared war and never threw his full support behind it . He even prevented his Imperial Knight s from participating . In 128 ABY , one year into the war , things were not going well for the Fel Empire : despite the Alliance handicap , the Jedi were more than making up for that . The Empire lacked the resources to counter the Jedi , and due to Fel ' s Imperial Knights not entering the war , the Sith insinuated themselves into the conflict . Through Nyna Calixte , the ruthless and ambitious Director of Imperial Intelligence and Moff , the Sith approached the Empire and allied themselves with the Imperial cause . When the Sith revealed themselves openly the Jedi knew that they were behind the sabotage of the Vong terraforming processes , but unfortunately weren ' t able to prove it in time to stop the war . Even members of the Imperial camp — including Emperor Fel himself — realized the truth of it , though far too late to halt the plans the Sith had set in motion . The Yuuzhan Vong , upon learning the truth , were at first relieved that it was not the work of their gods , then determined to reverse the damage the sabotage had caused . Shaper Nei Rin journeyed from Ossus to try to discover the Siths ' method of sabotage , hoping that this knowledge could help discredit the Sith and end the war . After three years of bloody warfare , the Galactic Alliance was easy to conquer , while the Sith only grew in power and strength , even independently manufacturing and fielding their own starfighters . . Imperial forces had even retaken Coruscant after more than a century since the final death of the cloned Palpatine . The Alliance finally surrendered , and its holdings were absorbed into the Empire , with the Galactic Alliance Core Forces remaining to fight the new Empire . It is unknown if the Empire made any efforts to eradicate the Yuuzhan Vong . The Emperor called on the Jedi Order to surrender and submit to the Empire ; some of them did , becoming the Imperial Knight s . But the rest , remaining true to the will of the Force , refused to ally themselves with the Sith and withdrew from Coruscant to their praxeum on Ossus . The Sith eventually followed the Jedi there , and Darth Nihl himself led a brutal attack on Ossus , aided by Imperial forces led under Moff Rulf Yage . The Massacre at Ossus scattered the Jedi across the Galaxy , though the order was not yet entirely destroyed . A few Jedi would later return to the planet under the noses of Imperial patrols sent to keep a periodic eye on it . Some Yuuzhan Vong , including the Master Shaper in charge of the Project , Nei Rin , also came back to safeguard what Jedi artifacts that hadn ' t been looted by pirates in the aftermath of the Massacre . Cade Skywalker eventually resumed his training on the world under his old Master Wolf Sazen . Shortly after , the Sith , determined to rule the galaxy themselves , launched a revolt to assassinate Emperor Roan Fel and his Imperial Knights . After killing what he later determined to have been a fake , Darth Krayt ascended to the Imperial throne himself , restoring , for the first time in a century and a half since Palpatine , the rule of a Sith Lord over most of the galaxy . Opposition to Krayt ' s Empire continued in the form of a rival Imperial faction that remained loyal to Roan Fel and the Galactic Alliance Remnant , which operated from portions of the Alliance that hadn ' t yet been subdued .