Devaron massacre

Previously, during the Clone Wars era between the Galactic Republic and the Confederacy of Independent Systems in 21 BBY, the planet of Devaron had already become a contested hotspot. Cad Bane, a bounty hunter hired by the Sith Lord Darth Sidious, launched an assault on a base operated by the Jedi Order using forces from the Separatist Droid Army, eliminating the clone trooper contingent stationed there. Jedi General Bolla Ropal was captured by Bane's forces along with the Kyber memory crystal, and subsequently tortured until his death. The arrival of Jedi General Anakin Skywalker's fleet led to the destruction of Bane's Trade Federation fleet. However, Bane managed to escape with both the crystal and a holocron that he had acquired before, though the Jedi later reclaimed these items. In the aftermath, Devaron was once again under the firm control of the Republic and the Jedi.

In 20 BBY, with the Jedi Order in possession of the strategically important Temple of Eedit on Devaron, Count Dooku tasked his newly acquired apprentice, Savage Opress, with retaking the outpost to secure a Separatist presence in that region of the galaxy. The fighting on Devaron took place after the Battle of Sarrish, a major defeat for the Republic.

Before Savage Opress reached the temple, a contingent of Separatist battle droids, specifically B1-series and B2-series models, had already landed on the planet and initiated their assault on the temple. Defending the temple were Jedi Master Halsey and Knox, his Padawan, along with their ARF troopers commanded by Clone Commander Trauma. As the Confederate forces advanced along Eedit Road, the Republic's forces found themselves isolated. Trauma led a group of clones at the front to repel the enemy droids, while Halsey, Knox, and a small group of clones defended the temple entrance against a wave of battle droids.

Upon Savage Opress's arrival, he swiftly advanced towards the temple, dispatching battle droids along his path. Opress quickly killed over half a dozen ARF troopers with his pike. Commander Trauma then directed his remaining troops to focus their attention on Opress. Trauma charged towards Opress to confront him, but he was killed when Opress sliced him upwards with his spear, launching Trauma into the air. Following Trauma's demise, the remaining ARF troopers were eliminated, and Master Halsey and Knox overcame the droid forces surrounding them. Once Opress reached the Jedi, Halsey stepped forward to engage him, instructing his padawan to remain behind. Opress skillfully evaded the Jedi Master's lightsaber strikes, and after disarming Halsey, they engaged in a brief hand-to-hand fight. Opress quickly gained the advantage, knocking Halsey to the ground and impaling him with his spear, resulting in Halsey's death. After witnessing his master's death, Knox charged at Opress, but he was killed with a single strike of the spear, sending Knox's body crashing back into the temple door. Ultimately, the entire Republic force was annihilated, along with all Separatist forces present, except for Opress.

Following his victory over the Republic forces, Opress contacted Count Dooku, informing him that the temple was now under their control. He was then instructed to return to Serenno. Upon Opress's return to Dooku's palace, Dooku expressed his belief that Opress would achieve great things as his new apprentice, suggesting that together they would surpass Lord Sidious in power and rule the galaxy. After the massacre, Delta Squad—Boss, Fixer, Sev, and Scorch—was dispatched to recover the bodies of the fallen Jedi and retrieve the Temple's security footage, reporting their findings to the Jedi Temple.

After Jedi Masters Obi-Wan Kenobi, Plo Koon, Saesee Tiin, and Adi Gallia were informed that everyone at the Temple of Eedit, including the Jedi, were dead, they discussed among themselves who had the ability to carry out the massacre. Master Gallia stated that in the past, only Count Dooku's assassin, Asajj Ventress, was capable of such action. Master Koon believed that it could be a newly appointed Sith Lord. Masters Yoda and Windu showed Kenobi the footage from the temple. Kenobi, upon seeing, thought it was Darth Maul alive. However, Yoda and Windu told him that it was not Maul, but a Zabrak from Dathomir, not Iridonia as Kenobi originally believed Maul was from. The Jedi Council dispatched Kenobi and Skywalker to Dathomir, specifically to the village where Maul and Opress originated.

Already deeply affected by events such as the Battle of Abrion Bridge, the massacre proved to be too much for Commander Mekedrix, a member of the Republic-aligned Roonian defense force, to bear. Driven to madness and convinced that the true master of the galaxy was destruction itself, Mekedrix deserted the Republic Military, disappearing without a trace. When he began to attack both sides of the war as the leader of the Death Wind execution squad, Republic officials suspected Mekedrix's involvement but were unable to confirm as such. Three months after the Death Wind's attack on Minntooine, Admiral Wullf Yularen recounted Mekedrix's suspected descent into madness following the Devaron massacre before sending Skywalker and Kenobi on an unofficial mission to bring him to justice.