The Ruusan campaign represented the concluding military actions of the New Sith Wars. Sometimes referred to as simply the Battle of Ruusan, a term also used to specifically denote the seventh engagement, this campaign encompassed seven major battles, alongside several smaller conflicts, all fought on the planet Ruusan. These battles unfolded over a period of two years, spanning from 1002 BBY to 1000 BBY.
During this campaign, the forces of the Galactic Republic's Army of Light were under the command of Jedi Lord Hoth, while the Brotherhood of Darkness was under the leadership of Skere Kaan, the Dark Lord of the Sith. Throughout the series of battles, both sides attempted to reinforce their positions on Ruusan, but many Jedi reinforcements were destroyed by a Sith blockade in orbit, and many Sith reinforcements were destroyed by the Republic Navy while traveling to Ruusan. The Army of Light emerged victorious in four of the seven major engagements, but the Sith achieved a decisive victory in the initial Battle of Ruusan, completely annihilating the Republic forces, with no survivors.
The concluding battle resulted in the destruction of the Brotherhood of Darkness, and after thousands in the initial battle, a final hundred Jedi. The Jedi sacrificed themselves to compel Lord Kaan to trigger his ultimate weapon, the thought bomb, within the underground caverns of Ruusan, eliminating himself and all the Sith Lords present. This highly debated decision, combined with the extensive damage inflicted upon the planet by the ongoing battles in space, air, and on the ground, along with the ecological consequences of the thought bomb, ultimately led to the Ruusan Reformation under Supreme Chancellor Tarsus Valorum, as well as the implementation of the Rule of Two by Darth Bane, who had secretly orchestrated these events to eliminate the Brotherhood of Darkness and begin anew with only his apprentice, with the goal of conquering by stealth and deception.
The Campaign and the seventh battle were initially referenced within the novella titled Dark Forces: Rebel Agent. In Dark Forces: Jedi Knight, according to Hoth's statements, as experienced in a vision by Kyle Katarn, the Brotherhood only secured victory in two of these battles. However, Darth Bane: Path of Destruction indicates that the Sith were victorious in the First, Second, and Fourth battles.