The Third Galactic War represents a major armed struggle that erupted across the vast expanse of the galaxy. It pitted the re-established Sith Empire against a coalition comprised of the Galactic Republic, the Jedi Order, and the Eternal Alliance.
Amidst the intensity of the second Galactic War, both the Empire and the Republic found themselves under a surprising attack from the enigmatic Eternal Empire, originating from the uncharted territories of Wild Space. This led to the formation of a tenuous alliance between the two superpowers, embodied by Dark Council member Darth Marr and the Republic's celebrated war hero, later known as the Outlander. While searching for the former Sith Emperor in Wild Space, Darth Marr's flagship was suddenly ambushed by the Eternal Fleet of the Eternal Empire. Both Marr and the Outlander were captured and transported to Zakuul, the capital planet, where Marr met his death at the hands of the Emperor, and the Outlander was imprisoned in carbonite.
Following his assassination of his own father, the new Emperor Arcann initiated a widespread invasion of the galaxy, subjugating both the Empire and the Republic and transforming them into puppet states under Zakuul's control. Years after this conquest, the Eternal Empire was overthrown by the Outlander, then known as the Alliance Commander, who seized Zakuul in the name of the newly formed Eternal Alliance. After securing a costly victory in eliminating the last remnants of the Eternal Empire's followers, the Commander opted to forge a closer working relationship with the Galactic Republic.
In 3628 BBY, the Sith Empire discovered the whereabouts of Jedi Master Gnost-Dural, who was presumed dead for a long time. He was found hiding within a secret Jedi Colony located on Ossus. Darth Vowrawn, the Sith Emperor, swiftly commanded an invasion of the planet. This operation was led by Darth Malgus and Darth Malora, a member of the Dark Council, thereby initiating the Third Galactic War.
The planet Dantooine became a target for the Sith Empire. Encountering strong defenses, the Sith collaborated with the Nova Blades pirates. Colonel Lenora Trazen from the Imperial forces spearheaded efforts to destabilize Dantooine. The Republic was caught off guard by the Nova Blades' unexpected assault, but the pirates, driven by greed, eventually turned against the Empire as they began their plunder. Ultimately, the Commander of the Eternal Alliance intervened, assisting the Republic in the defense of the planet.
In 3627 BBY, King Regalun Petryph sought to exploit the resources of Onderon for his personal enrichment. This ambition put him at odds with Senator Deja Nebet and her council of nobles. Unbeknownst to Petryph, he fell under the influence of Darth Savik. Savik, with the intention of seizing control of Onderon's resources, manipulated Petryph into igniting a civil war by convincing him that Nebet and the nobles were conspiring against him.
A Republic fleet, commanded by Vice Admiral Dol Narlock, made a stop at Mek-Sha to refuel while en route to Corellia. Simultaneously, Darth Shaar devised a plan to obliterate the fleet, aiming to weaken the defenses of Corellia. Mek-Sha's independence, secured by a fuel failsafe established by the station's queen, Huttbreaker, became crucial to the Empire's scheme to destroy the Republic ships. The decision of whether to permit the Republic to refuel rested on a vote by Mek-Sha's crews, with Junker Jott, a Republic sympathizer, and Huttbreaker both supporting the fleet's cause.
Shortly after the mission on Mek-Sha, the Sith Empire, under the leadership of Darth Malgus, launched a large scale assault on the Republic. One fleet targeted the Republic fleet, while another bombarded the planet's surface as a diversion. Meanwhile, Malgus led a ground assault on the Meridian Complex. The Alliance Commander, Jedi Knight Tau Idair, and Padawan Arn Peralun pursued Malgus, ultimately confronting him and restoring the complex's defenses. Malgus was forced to retreat, and Krovos' fleet was compelled to withdraw.
In 3626 BBY, Darth Malgus, haunted by visions of his defeat and capture by Emperor Vowrawn and Darth Krovos, sought a means to rid himself of these tormenting effects. Upon arriving at the ruins of the Jedi Enclave on Dantooine, Malgus ventured deeper into the ruins, where he unearthed an ancient relic that once belonged to Darth Nul, an ancient female Sith Lord whose existence had been erased from historical records. Soon after, the Jedi were dispatched to the Enclave to investigate the ruins.
Around 3625 BBY, the Sith Empire invaded the ocean planet Manaan with the intention of seizing its mass-produced and highly valued kolto, hoping to shift the balance of the war in their favor. They faced opposition from Republic forces who were supporting the Selkath in an effort to thwart the Empire's objectives. Meanwhile, the renegade Sith Lord Darth Malgus journeyed to the Temple of Nul on the planet Elom. Simultaneously, the Jedi had uncovered the mystery surrounding Darth Nul and discovered a connection between the planet Elom and Nul, believing it to be the place where Malgus was seeking answers. Jedi Master Denolm Orr then assembled a team, including his Padawan Sa'har Kateen, to investigate Elom.
During the mission, Denolm Orr's team encountered Imperial forces on Elom, resulting in only him and his Padawan surviving to reach the temple. Inside, they discovered a mysterious machine powered by a holocron. Orr and Kateen were soon confronted by a Sith warrior. As they engaged the Sith warrior, Malgus unexpectedly intervened, killing the Sith as he entered the temple. While Malgus and Orr dueled, Sa'har interacted with the machine, experiencing a vision of her past. After Orr destroyed the machine, Sa'har retrieved the holocron but refused to relinquish it, leading to a conflict between her and Orr. Malgus seized the opportunity, killing Orr, burying Sa'har under rubble, and taking the holocron.
Malgus later encountered the Alliance Commander, Tau Idair, and Lana Beniko who had just arrived on Elom, resulting in his defeat. He was subsequently imprisoned aboard Carrick Station. Meanwhile, Sa'har survived the temple's destruction, located the holocron hidden by Malgus, and departed from the planet.
During the Mandalorian civil war between Mandalore the Avenger's faction and the splinter faction known as the Hidden Chain, Field Marshal Heta Kol of the Hidden Chain sought to exploit Darth Nul's holocron to create an army of Force-sensitives. Around 3623 BBY, the Alliance Commander and Sa'har Kateen infiltrated their flagship in an attempt to stop Heta Kol. After defeating Sa'har's brother, Ri'kan, and sabotaging the Holocron Machine, the Commander attempted to assist the siblings, but falling debris blocked the path, forcing the Commander to escape the flagship with the holocron. Simultaneously, Shae Vizla and her mercenaries broke Malgus out of Carrick Station, fearing that Heta Kol's war would provoke both the Galactic Republic and Sith Empire. To avert the potential destruction of all Mandalorians, Vizla aligned herself with Malgus, viewing him as the only one capable of stopping Heta Kol.