At some point after 3522 BBY, a conflict was sparked between the Jedi Order and the forces of the Pau'an Dark Lord of the Sith Darth Desolous. A Jedi Master expelled from the Order for studying Sith teachings, Darth Desolous swore revenge on the Jedi, assembled an army of Pau'an warriors, and trained them in his personal style of martial arts. His forces killed nearly two thousand Jedi Knights, until Desolous and his army were finally defeated by a Jedi strike force during a battle on the planet Yaga Minor.
Sometime after 3522 BBY, a Pau'an Jedi Master was expelled from the Jedi Order for studying Sith teachings and falling to the dark side of the Force. Angered at his expulsion, the individual became the Dark Lord of the Sith Darth Desolous and swore revenge on the Jedi. He assembled an army of Pau'an warriors and trained them in his personal style of martial arts. The style combined the usage of a melee weapon with a lightsaber-resistant cortosis shield; the shield was used to block an opponent's attack, leaving the being open for a quick counterattack.
Darth Desolous, the instigator of the conflict
Desolous led the Pau'ans in a series of ambushes against Jedi Knights throughout the galaxy, slaughtering almost two thousand Jedi. With each successful murder, Desolous grew more reckless and bold, and the Jedi decided to exploit those traits. A small force of Jedi Knights was sent to the planet Yaga Minor, acting as bait for the Sith Lord, while a large Jedi fleet remained hidden nearby. When Desolous and his army struck the Jedi on the planet, the fleet emerged from hyperspace and prevented the Sith Lord's forces from retreating. Caught into a tactically disadvantageous position, Desolous's men were all killed, and Desolous himself was struck down.
As time passed, Darth Desolous's original name was forgotten, but his Sith name became synonymous with hatred and anger. A simulacrum of Desolous was later incorporated into the Jedi Trials program for Padawans at the Jedi Temple on the planet Coruscant. The life-like manifestation could appear in the Trials chamber during the "Trial of Skill," and was meant to test an apprentice's ability to overcome raw emotions. The simulacrum of Desolous was aware of his physical death; it took pride in the murders the real Desolous had committed and claimed that it had required the entire Jedi Council to kill him.
This conflict was mentioned in the PlayStation 2, Wii, and PlayStation Portable versions of the 2008 video game Star Wars: The Force Unleashed, developed by Krome Studios. The conflict was detailed in the game's databank entry on Darth Desolous. In the game itself, the player, controlling the Sith apprentice Starkiller, faces against the simulacrum of Desolous inside the Jedi Temple. During the fight, the simulacrum exclaims random taunts and battle cries, and at one point claims that it required the entire Jedi Council to kill the real Desolous. Desolous's databank entry makes no mention of the Council; thus, the simulacrum's claim remains unconfirmed by any official source to date.