Battle of Dathomir

Since the Clone Wars' inception, Asajj Ventress served as Count Dooku's Sith apprentice. She effectively spearheaded Separatist forces in numerous clashes against the Galactic Republic. However, during the Battle of Sullust, Darth Sidious, Dooku's Sith master, contacted the Count. Sidious voiced concerns that Ventress had become excessively powerful, suspecting she was being groomed to overthrow Dooku and seize power, consistent with the Sith Rule of Two. Despite Dooku's denials, Sidious disregarded them and instructed the Count to eliminate Ventress as proof of his unwavering loyalty to the Dark Lord of the Sith. Dooku reluctantly conceded to this demand. Amidst the ongoing battle between the Republic and Confederate fleets, he withdrew her reinforcements and commanded the T-series tactical droid TJ-912 to target Ventress's ship, where she was engaged in a duel with Jedi General Anakin Skywalker and Master Obi-Wan Kenobi, Dooku's nemesis. Subsequently, Dooku used a hologram to inform Ventress that she was dismissed as his apprentice, withdrawing her reinforcements citing her repeated failures, and implying her impending death.

Despite Dooku's machinations, Ventress survived, escaping both the Jedi and the Confederacy. Having abandoned Dooku and the Separatist cause, she returned to Dathomir, her homeworld, where she rejoined the Nightsisters and began plotting revenge against Count Dooku.

Learning of Ventress's return to Dathomir, Dooku dispatched General Grievous, the Supreme Martial Commander of the Separatist Droid Armies, along with a Separatist fleet carrying a droid army, to eradicate Ventress, Mother Talzin, and the Nightsisters. This action served as retribution and was fueled by Lord Sidious's perception of Ventress's kinfolk as a threat to his emerging evil Empire.

Upon General Grievous's arrival, Ventress had completed her initiation, fully embracing her role as a Nightsister.

Grievous's fighters, comprised of Vulture-class starfighters along with Hyena-class Droid Bombers, bombarded the Nightsisters' stronghold, forcing them out of their concealed positions.

Accompanied by a fleet consisting of four Munificent-class star frigates, a pair of Recusant-class light destroyers, two Dual Hemisphere-Omni Support Vessels, and his flagship, the Providence-class Dreadnought, Grievous and his forces transitioned from hyperspace into the Dathomir system before landing on the planet's surface.

To bolster the Nightsisters at the front lines, Old Daka chanted the Chant of Resurrection, summoning the Army of the Dead, a legion of undead Nightsisters.

Upon their arrival, Grievous instructed his OOM-series security droids to commence the invasion by deploying troops onto the planet. The deployed forces included BX-series droid commandos, B1-series battle droids, B2-series super battle droids, IG-100 MagnaGuards, a Defoliator Deployment Tank, and Multi-Troop Transports.

After securing the front lines, Grievous's forces pushed the Nightsisters back towards their fortress. Following the slaughter of most Nightsisters, Grievous breached the fortress, demolishing the wall to access the Hidden Cave. He then impaled Daka with a lightsaber and overturned her ichor cauldron, disrupting Dooku's voodoo torture. With Daka's demise, the zombie Nightsisters were also vanquished, leaving the remaining living sisters to be massacred by the Droid Army. Despite the Nightsisters' valiant and fierce resistance against the droids, the battlefield was littered with more fallen witches than droids; even the undead could not endure the onslaught, leaving no one to tend to the deceased.

With Ventress in flight and the loss of their undead reinforcements, the remaining Nightsisters scattered into the forests, relentlessly pursued by hordes of battle droids. Among them were Morgan Elsbeth and her mother Selena, part of a group of Nightsisters hunted by Grievous's droids. As the sisters prepared for their last stand, Grievous ambushed them, opting to confront Selena directly while commando droids engaged Morgan and the other Nightsisters. After killing Selena and taunting Morgan to flee, Grievous ordered his forces to eliminate the remaining Nightsisters, transforming the landscape into a scorched wasteland.

With the battle concluded and her fellow Nightsisters slain, Ventress traversed the forest and encountered Talzin, appearing as a spirit. Ventress blamed herself for the devastation, but Talzin reassured her that, despite the eternal connection between the Nightsisters and Ventress, she now had her own path to forge. Ventress pleaded with Talzin not to leave her, but the Nightsister mother departed. Consequently, Ventress departed from Dathomir. Talzin remained on the planet, maintaining contact with her sons Maul and Savage Opress, Sidious’ first Darth. A dying Daka dispatched the nightsister Yenna off-planet in an escape pod. Merrin and Jerserra mourned the loss of their sisters, with Merrin burying the clan's members including her best friend/romantic interest, Ilyana. Shelish, who had left Dathomir in her youth years prior, was at least one Nightsister who completely avoided the devastation of her people by being located offworld, sought to honor their memory after the massacre.

In the aftermath of the battle, Ventress sensed a disruption in her connection to the Force. Seeking the new life Talzin had spoken of, Ventress ventured deep into the Outer Rim, eventually arriving on the desert world of Tatooine. Upon entering a cantina on Tatooine, Ventress realized that no one was aware of the slaughter of her people, leading her to view the Battle of Dathomir as the effective end of her homeworld. After participating in safe cargo objective, she recalled Talzin's final words, but without the same pain. Instead, she felt she had always had a path and that, after losing it for some time and becoming so many things throughout her life, she was herself, with the entire galaxy waiting for her. She then embraced the life of a bounty hunter.

To eliminate any remaining Nightsisters, Grievous deployed patrols consisting of HMP droid gunships, probe droids, and battle droids across the forests and mountains, tasked with hunting down any survivors of the Separatist invasion.

It was believed that no Nightsisters had survived the atrocities of the Clone Wars. As years and decades passed, the survivors, haunted by the memory of their sisters being slaughtered by an armored warrior wielding a lightsaber—whose identity remained unknown—waited for the opportune moment to seek vengeance for their fallen kin. Legends circulated about the Nightsisters' annihilation during the Clone Wars. During the Imperial Era, Jerserra was discovered by a female Inquisitor who trained her in the ways of the dark side. When showing the young Jedi Ezra Bridger the ruins of the Nightsister lair, Maul claimed that the Nightsisters posed a threat to the Empire, leading to their extermination during the Clone Wars.

Morgan Elsbeth also survived, witnessing her mother's demise and remaining hidden after defeating the droids in her vicinity. She later pledged allegiance to the Empire, contributing to the construction and expansion of the Imperial Starfleet by exploiting worlds for their resources. Driven by bitterness from the genocide of her people, she sought power and revenge. Despite questions about her Nightsister heritage, Elsbeth considered herself a survivor and ventured into the era of the New Republic, where she located her lost master Grand Admiral Thrawn, and rescued him from his exile in a far galaxy that was the original home of her family.

The Battle of Dathomir was conceived for the Star Wars: The Clone Wars animated series and was showcased in the episode "Massacre," which premiered on February 24, 2012 as part of the series' fourth season. In December 2012, StarWars.com recognized the Battle of Dathomir as the third most memorable moment of the television series from that year.

The Battle of Dathomir is also referenced in the 2017 video game Star Wars Battlefront II via its character DLC. When a player spawns into a match as Grievous, he may utter "this will be easier than Dathomir!" as his initial line.