- "There were no survivors on Devaron. Everyone was killed, including Master Halsey and his Padawan"
- ―Clone Commando Boss reports on the aftermath of the battle
The Devaron massacre, was the result of a battle for control of the Temple of Eedit on the planet Devaron during the Clone Wars. The battle was a terrible loss for the Galactic Republic, which suffered yet another blow in its long campaign against the Confederacy of Independent Systems.
With the Jedi Order in control of the vital Temple of Eedit on Devaron, Count Dooku ordered his recently acquired apprentice, Savage Opress, to take back the outpost, so that the Separatists could have a foothold in that corner of the galaxy. Prior to Savage Opress arriving to the temple, Jedi Master Halsey and Knox, his Padawan, along with their ARF troopers led by Clone Commander Trauma, were defending the temple against Separatist forces, which included B1 battle droids and B2 super battle droids. The Republic force was cut off, with a group of clones led by Trauma in the front to fend off enemy droids, while Halsey, Knox, and a handful of clones defended the temple entrance from a group of battle droids.
Once Savage Opress arrived, he quickly made his way towards the temple, knocking battle droids out of his way. After Opress quickly killed more than half a dozen ARF troopers with his spear, Commander Trauma ordered his remaining men to focus their attention on Opress. Trauma rushed towards Opress to face him but was killed when Opress sliced him upwards with his spear, launching Trauma into the air briefly. After Trauma's death, the remaining ARF troopers were killed, and Master Halsey and Knox defeated the droid forces surrounding them. Once Opress had reached the Jedi, Halsey moved forward to face him, ordering his padawan to stay back. Opress was able to quickly dodge Halsey's lightsaber swings, and after disarming Halsey, they briefly fought in hand-to-hand combat. Opress quickly gained the upper hand, striking down Halsey to the ground and impaling him with his spear, killing Halsey. After the death of his master, Knox ran towards Opress, but was killed in a single strike of the spear, sending Knox's body all the way back to the temple door. In the end, the entire Republic force was destroyed, as well as all present Separatist forces except for Opress.
After Opress defeated Republic forces, he contacted Count Dooku informing him that the temple was now under their control, and was ordered to return to Serenno. After the massacre, Delta Squad was sent to recover the bodies of the fallen Jedi, and reported to the Jedi Temple. After informing Jedi Masters Obi-Wan Kenobi, Plo Koon, Saesee Tiin, and Adi Gallia that everyone on Devaron, including the Jedi, they discussed among themselves on who had the ability of the massacre, with Master Gallia stating that in the past, only Count Dooku's assassin, Asajj Ventress, was capable of such action.
- Star Wars: The Clone Wars – "Monster" (First appearance)
- Star Wars: The Clone Wars – "Witches of the Mist" (Appears in hologram)
- The Weapon of a Jedi: A Luke Skywalker Adventure (Indirect mention only)
- (First identified as Devaron massacre)
- Star Wars: Galactic Atlas