The Korriban Incursion, also known as the Republic Occupation of Korriban, was a battle that occurred in 3637 BBY during the Galactic War between the Galactic Republic and the Sith Empire. The Republic's objective in the battle was to retrieve a set of data from the Dark Council's chamber in the Sith Academy on the planet Korriban.
The initial assault titled Wave One managed to breach the Valley of the Dark Lords before being halted by the strong Imperial defenses. The second wave, which consisted of four Republic heroes, reinforced their position, taking out the four key Imperial ground commanders before facing Lord Renning and killing him. They then had to help Republic forces decide whether or not to free the Imperial slaves, as it was not within their mission parameters. They then made their way into the Sith Academy.
Inside the Academy, the heroes defeated Sith instructors to unlock the turbolift to the Dark Council Chamber. Once they ascended the turbolift, the heroes fought their way to the Chamber and defeated Darth Soverus. Jedi Commander Jensyn arrived with reinforcements and struck down the Sith, but not before Soverus mentioned an 'old man' having foreseen the conflict.
The main heroes returned to Colonel Rian Darok and Theron Shan for a mission debriefing, but word of the concurrent Assault on Tython forced them and a large group of the Republic forces to leave the assault to help retake the Jedi planet. The Sith Empire would retake Korriban shortly afterward and kill the large occupation force of Jedi and Republic troopers, killing many powerful Jedi Knights as well as Jedi Masters in the process.