During the early days of the Clone Wars, a conflict erupted on the planet Thustra. It pitted the Galactic Republic's military against the rebellious Sephi people. Driven by a desire to emulate the Separatists, a faction within the Sephi increasingly advocated for their homeworld's independence from the Republic. The galactic government's response involved deploying a clone task force under the leadership of the Jedi. However, with Thustra under military occupation, the secessionist faction exploited the situation to galvanize further Sephi support for the rebellion.
The Sephi's dissatisfaction with the Republic's authority quickly escalated into animosity and overt acts of defiance. Employing a combination of guerrilla warfare and terrorist strategies, the insurgents aimed to weaken the Republic's occupying forces through a war of attrition. Despite these acts of aggression clearly qualifying as treason and acts of war, the government on Coruscant hoped to discover a solution that would result in Thustra remaining loyal to the Galactic Republic. Yoda, the Jedi Order's Grand Master and a key figure in its governing council, personally accepted the assignment as a Republic envoy.
Upon Yoda's arrival on Thustra, the Grand Army and its Jedi commanders found themselves in a dire predicament. Two Jedi Generals, Tyffix and Tyr, had been assassinated in a surprise terrorist attack. Their demise left the young Commanders Cal and Pix in command of the occupation force. Yoda, accompanied by Cal, set out for Thustra's capital city in a final attempt to negotiate an end to the hostilities between the Republic and the Sephi; Padawan Pix and Commander Clutch were instructed to stay behind and oversee the occupation force.
A few months following the First Battle of Geonosis, the Sephi leadership of the planet Thustra shifted their allegiance to the Confederacy of Independent Systems, effectively joining the rebellion against the Galactic Republic. As a consequence of the Sephi's treasonous actions, the Grand Army of the Republic deployed a contingent of clone troopers under the direction of Jedi Generals Tyffix and Tyr. It was hoped that a substantial display of military strength and the threat of force would be adequate to deter the Sephi from further acts of betrayal. However, the Sephi instead launched an assault on the Republic's military installation on the very day the Jedi and their clone forces landed.
The Republic's forces were almost immediately overwhelmed by the native population. Much of their defensive infrastructure had been decimated, especially along the southern perimeter. A Sephi pilot, acting as a suicide bomber, deliberately crashed their aircraft into the Republic command center, resulting in the deaths of Tyr and Tyffix. With both Generals deceased, command of the Republic's forces devolved to their respective Padawans, Commander Pix and Commander Cal. As the situation rapidly deteriorated, Pix transmitted a distress signal directly to Coruscant, the Galactic Republic's capital world. The message was intercepted at the Republic Executive Building and reviewed by Grand Master Yoda, Master Mace Windu, Master Oppo Rancisis and Supreme Chancellor Palpatine.
Given that the Sephi rebellion had the backing of Thustra's ruler, King Alaric, Windu felt that appeasement was an imprudent course of action; Thustra needed to be subdued through the application of force, not just its threat. Palpatine was adamant that Thustra could not be permitted to secede from the Republic, as the repercussions would be too severe. Highlighting Alaric's influence within his own region, the Chancellor emphasized that the entire Sumitra sector could potentially break away from the Republic if Thustra was allowed to do so. As a longtime friend of the King, Yoda hoped to persuade Alaric to reaffirm Thustra's allegiance to the Republic.
Shortly after his arrival on Thustra, Yoda journeyed to the Sephi capital city, accompanied only by Cal. Pix, who was left in charge of the Republic's armed forces, received strict orders not to engage the Sephi, so as not to jeopardize Yoda's attempt at negotiation. Although Alaric agreed to meet with the Grand Master of the Jedi Order, neither of the two old friends could persuade the other to change their minds. Alaric, who contended that the Republic was flawed and corrupt, implied that the Republic might eventually betray the Jedi who defended it. However, Yoda remained steadfast in his loyalty to the Republic, resulting in a stalemate between the two.
After the King placed the Jedi under house arrest, Senator Navi of Thustra, a loyalist but corrupt politician, sought to manipulate the Republic into restoring order on Thustra through military intervention. He first provided Cal with information that would facilitate the Jedi's escape from the palace. Navi then informed Pix that Yoda and Cal had been executed on King Alaric's orders. The young Jedi Commander was deceived by the Sephi Senator's fabrication and, as Navi had anticipated, responded with a full-scale assault on the Sephi capital. To ensure a Republic victory, Navi furnished Pix with the most up-to-date Sephi troop deployments, as well as intelligence on Alaric's palace.
Simultaneously, Moje, an assistant to Senator Navi, subtly spread rumors of a Jedi conspiracy to assassinate Alaric, thereby fueling even greater anti-Republic sentiment among the Sephi. Commander Pix, accompanied by Commander Clutch, personally led the clone troopers into battle against the Sephi forces that stood between the Republic's army and the capital of Thustra. While Pix and Clutch oversaw the ground forces during the firefight, the Republic launched an aerial bombardment of the Sephi, resulting in numerous enemy casualties, including Commander Dekluun.
Meanwhile, Cal and Yoda were attacked by the King's palace guards, which resulted in Cal's death. Yoda moved to confront his former friend alone, only to discover that Alaric had chosen to die as a martyr in order to further incite the Sephi to rebel against the Republic. Although his objective was realized, Alaric, in his final moments, pleaded with Yoda to remember their friendship as it once was, rather than what it had become as a result of the Clone Wars.
On Coruscant, Senator Navi attempted to exploit the situation on Thustra to garner support from his fellow representatives in the Galactic Senate. However, he was taken by surprise when Yoda, Pix, and Clutch entered the rotunda of the Senate Building, where they exposed the Sephi politician's deception to the other senators. Navi was apprehended and charged with treason, but the Republic's withdrawal from Thustra enabled the Sephi to secede from the Galactic Republic.