The Imperial Attack on Voss unfolded around 3645 BBY, amidst the Cold War that pitted the Galactic Republic against the reconstituted Sith Empire. Discovering that the newly-found planet Voss was home to the Force-sensitive Voss species, who possessed potent foresight abilities, the Sith Emperor commanded the Imperial Military to seize control of the world. General [Khypes], arriving in orbit aboard a battlecruiser accompanied by several army divisions, demanded the planet's capitulation, believing the Voss capital, Voss-Ka, to be defenseless.
However, the Star Cabal, a group intent on destroying both the Empire and the Republic, employed their advanced technology to seize control of the Sith fleet. Khypes's cruiser was destroyed in an explosion before he could establish contact with the planet, and its escort ships met a similar fate shortly after. During this time, agents working for the Emperor's Hand abducted a Voss individual from the planet's surface, acting on the Emperor's own purposes. Recognizing their misjudgment of the Voss, the Empire claimed Khypes had acted independently, leading both the Empire and the Republic to initiate diplomatic efforts with the Voss.
The initial mention of the Imperial Attack on Voss appeared on the official website for the Star Wars: The Old Republic video game. The game itself, along with its in-game Codex, later provided the event's name and more detailed background information.