The Republic learned of the existence of the Star Forge from former Sith Lord, Revan, and a young Jedi Knight, Bastila Shan. The two, with the assistance of eight other companions used Revan's memories as the Dark Lord to locate four ancient Star Maps, navigational artifacts the Infinite Empire constructed on conquered worlds as a monument to their power which led the finders to the Star Forge.

Before crashlanding on the Unknown Planet, Revan's team contacted the Republic Fleet, which arrived shortly after Revan disabled the protective disruptor shield of the Star Forge. Not surprised by his former master's plans, Darth Malak, the current ruler of the Sith Empire after usurping the position from Revan, ordered the immediate interception of the fleet, and expected a speedy victory thanks to the help of Bastila's Battle Meditation, whom Malak corrupted to the Dark Side after capturing her aboard the Leviathon.

With the Republic Fleet unable to make any effective attack on the Star Forge, and the Sith seeming to predict every strategic and tactical move of the Republic, Revan and his crew had no choice but to land on the Star Forge and bring Malak to justice themselves.

Revan and his team battled through seemingly endless waves of Sith troopers, Dark Jedi, and battle droids created by the Star Forge. Though Malak knew none of them would succeed in stopping his old master, they were providing him with enough time to prepare for their inevitable confrontation. When Revan finally cut through the Sith waves and made it to the Command Deck, Bastila, now even more powerful after her fall to the Dark Side, stunned his companions, and faced Revan in a brutal one-on-one confrontation. He defeated Bastila three times, who regenerated her strength using the power of the Star Forge during each interval. However, after a fourth time, she gave in to Revan, and drew on their bond to summon enough energy to stand against the omnipresent presence of the Dark Side. She turned her attention to aid the struggling Republic Fleet while Revan proceeded to the main Viewing Platform.

After facing and defeating more of the Star Forges battle droids's, Revan finally reached Malak. After a brief exchange of taunts, the two engaged in their final duel, Malak regenerating his strength by sapping the powers of Jedi kept in a state of suspended animation. Even this wasn't enough, as Revan eventually triumphed. He and his crew were able to escape the Star Forge just as the Republic Fleet hit the station's main orbital stabilizers, and it exploded.

**Taken from: http://en.wikipedia.org/wiki/Star_Forge