The Syndicate War was a multi-month long conflict that broke out during the reign of the Galactic Empire in the aftermath of the Attack on the Executor. That attack and the following conflict were manufactured by the resurgent Crimson Dawn criminal syndicate as part of secret war waged by its leader, Lady Qi'ra, to destroy the Sith Darth Sidious and Darth Vader, ending their rule over the galaxy and bringing forth a new power structure. The war saw a number of syndicates and groups turn against one another, disrupting the criminal underworld. Upon realizing the plot against him, Sidious moved to crush Crimson Dawn and contacted the heads of the warring syndicates, ordering them to stop the pointless conflict and instead locate and kill Qi'ra.
In order to cause the war, Qi'ra and her associates met with other syndicates, passing along the false rumor that, following the Empire's destruction of the Hutt Council for their Attack on the Executor, the Empire was searching for a new partner to replace the exclusive deal they held with the Hutts. At the same time, Qi'ra had the bounty hunter Chanath Cha and the Orphans discreetly attack the syndicates, who, unsure which of their rivals were at fault, blamed each other. The distrust that the attacks caused, combined with the rumor that the Empire was searching for the strongest syndicate, lead to the outbreak of fighting between the syndicates. As Qi'ra had intended, Darth Sidious—publicly Emperor Sheev Palpatine—took notice of the war, calling for Darth Vader to take action.
After the outbreak of the War, Sidious told Grand Vizier Mas Amedda to inform General Maximilian Veers and Admiral Firmus Piett that the Imperial fleet was to put an end to it. The conflict ultimately carried on for months. In time, Sidious realized that the Syndicate War and other recent events were proof that the Sith had a specific enemy, who were using the chaos of the Syndicate War and other events to cover up their true plans. Summoning Vader to the Imperial Palace, Sidious and his right hand man met with Director Barsha, whose division of the Imperial Security Bureau kept tabs on the criminal underworld and thus had studied the on-going conflict. Relaying the rumor that kicked off the War, Barsha informed Vader and Sidious that Crimson Dawn had engineered the entire struggle. In response, the Sith ordered the entire Imperial Military to locate the Crimson Dawn flagship Vermillion, which resulted in Qi'ra ordering her agents in every major galactic faction, including the Empire, to cause chaos as the start to her "Hidden Empire."
Palpatine personally put an end to the Syndicate War by contacting the heads of the warring crime families and, reminding them that the galaxy was under his rule, demanding that they cease what he termed to be a "pointless" conflict. Revealing the role of Crimson Dawn in manipulating galactic events, Palpatine ordered that they put the resources and resolve they had used against each other to fighting Crimson Dawn, promising to value any syndicate that killed Qi'ra and brought him her remains. After the fall of Crimson Dawn and the failure of Qira's plans, the war and its surrounding events were documented in a holocron by the Archivist, a Force-sensitive individual who had allied with Qi'ra in her plot.
- Star Wars: The Rise and Fall of the Galactic Empire