The Jedi Civil War is a conflict in the fictional Star Wars galaxy that took place 3,956 years before the Battle of Yavin, as seen in Star Wars: Episode IV—A New Hope. It is also known as the second Sith War and the War of the Star Forge, and is grouped together with other conflicts of close temporal proximity under the name of the Old Sith Wars.

Origins

The Mandalorian Wars

Nearly 4,000 years BBY, a warrior race known as the Mandalorian Neo-Crusaders began raiding worlds on the edge of the galaxy. The Jedi Order insisted on staying out of the war, but Revan, followed by his best friend, fellow Jedi Malak, left with a force of rebellious Jedi Knights to defend the galaxy. After a series of battles, Revan and Malak crushed the Mandalorians and won the war, ending with a bloody battle at the planet of Malachor V. Revan truly earned the awe and respect of the militaristic Mandalorians, who had served Ulic Qel-Droma, the apprentice of the previous Dark Lord of the Sith, Exar Kun, in the Great Sith War. At the final battle of the war, Revan discovered the Trayus Academy on Malachor V, where he was corrupted by the teachings of the Sith. Malachor V was an ancient storehouse of the Sith that was steeped in a darkness so great that it almost destroyed Revan, but he survived and overpowered it: but only by giving in to the dark side of the Force and becoming the new Dark Lord of the Sith. It is there he also discovered secrets that enabled him to turn many Jedi to his Sith cause. Shortly after winning the war, Revan, Malak, and the Jedi and Republic forces who followed them disappeared from Known Space.

The Jedi Council was outraged at Revan and Malak's rebellious actions, for they knew there was a more sinister force behind the Mandalorians' sudden offensives. Though they did not know it, the ancient Sith Empire, believed dead for almost a thousand years, was in fact hiding in the Unknown Regions, waiting for the right moment to return. When the Jedi Civil War began, the council blamed it on Revan and Malak, and their transformation into Sith. But the origins of the war most likely lie in the unyielding teachings of the Jedi Order, the same teachings that drove the Jedi Council to remain on Coruscant and do nothing while the Outer Rim burned. This extract is from a Jedi Exile, an older and more experienced Padawan who followed Revan to war, serving as one of his top generals, overseeing the Battle of Malachor V, and being the only Jedi under Revan who turned away from the dark side after the Mandalorian Wars:

I was the only one who returned to the council after Malachor V, only to be accused of disobedience and immediately exiled.

I was not as angered as I was devastated. Devastated that the Jedi could not even admit their mistakes. That perhaps their teachings were too extreme. That maybe it was better to endeavor to understand why we few Jedi favored action over inaction at the start of the Mandalorian War.

The council called us rash and battle hungry. The dark side, they said, is what drove us, what we sought.

How could the Jedi compare us to such evil when we had sacrificed so much to aid the Republic, which would have surely lost if we had not intervened?

These Jedi, who I began to look on with a different eye. I saw their faces as they judged me on Coruscant. Even they, the twelve great Masters, could not hide their emotions of anger, of hate. Emotions that feed our darker side. This hate and punishment, from the supposed "compassionate, open-minded" Jedi is probably what caused so many to leave the order and follow the new Lords of the Sith: Malak, the apprentice, and the powerful Revan, the master.

Their fall to the dark side is, in my eyes, a failure of the Jedi Order to educate its students to all truths, all secrets. For it is only when you have provided all knowledge and views to a wise student that he or she can choose the right path. Otherwise, his deprived, mischievous, hungry heart breeds a passion which surpasses all logic and drives him to seek that which is held from him - good or evil . . .

And now, I, an exile, wander the galaxy while a new war rages, a war of hate and betrayal rooted in the absolutism of the Jedi and their Code. I cannot help feel guilty that we Jedi, good and evil, are once again the leaders in a bloody war, now pitted against each other. We carry millions of soldiers with words of glory and justice, yet what really drives us are our scars of the past and our lust for revenge.

Prelude to War

Shortly before their disappearance, Revan and Malak had gone to Dantooine, where Revan, using secrets he had learned on Malachor V, unlocked a structure of primeval Jedi ruins, revealing an ancient Star Map. This Star Map led them to others, on Tatooine, Kashyyyk, Manaan, and Korriban. It was on this last world that their fall became complete, and Revan and Malak, their Jedi ideologies warped by the dark powers they had uncovered on Malachor V and Korriban, became the new Lords of the Sith. Taking the names Darth Revan and Darth Malak, the two friends battled for supremacy, with Revan emerging the victor and declaring himself the new Dark Lord. Revan and Malak, now beholden to the dark side, created a massive fleet to destroy the Republic and the Jedi, reforming the Republic forces who followed them into a militaristic empire and used the ancient Rakatan Star Forge factory, a relic from the pre-Republic Infinite Empire they had located using the Star Maps, to build up a massive war fleet. A year after their disappearance, Revan and Malak reappeared in Known Space, and the galaxy tremled at their return.

The Second Sith War Begins

Thus began the second Sith War, a conflict that proved even more devastating than Exar Kun's war as even more Jedi fell to the dark side, were killed in battle, or were murdered by specially-trained Sith Assassins. Revan was the greatest military genius the Jedi had ever seen, and it had been through his cunning alone that the Mandalorian Wars had been won, as the Republic soon discovered. Aware of the threat posed by the forgotten of the ancient Sith Empire in the Unknown Regions, Revan was careful to preserve the Republic's shipyards for use after he and his apprentice had conquered the galaxy. His reinvigorated Sith won battle after battle, until a young Jedi Padawan named Bastila Shan came into the fold with her Battle Meditation, a rare and powerful ability of the Force that increased the combat effectiveness of the Republic's forces and attacked the will of enemy combatants, after which point the war became a conflict of attrition. Even with this power, however, the Republic forces knew that they could not hold out forever against the Sith. In a desperate attempt to end the war, the Republic set a trap for Revan and Malak, during which Bastila and a team of Jedi boarded Revan's flagship and managed to corner the Dark Lord on the bridge. As one of the most powerful Sith Lords of all time, it is likely that Revan would have defeated Bastila and the remnants of her Jedi strike force, but Malak chose that moment to attack his master's flagship, attempting to kill both Revan and Bastila at once, and so seize the mantle of Dark Lord and eliminate the greatest threat to the Sith Empire in a single stroke. He fired upon the flagship from a nearby battle cruiser, but was successful in killing neither his master nor Bastila, though the former was all but dead. Knowing that a Jedi reveres all life, even that of a Sith, Bastila used the Force to save Revan's life, thus forming a powerful bond between the two. In the chaos, Revan, still nearly dead, his mind damaged beyond recovery, was captured by the Jedi. His broken mind was reprogrammed by the Jedi Council to hide the Dark Lord's old identity, while enabling the Jedi to use Revan's subconscious memories to locate the source of the Sith's seemingly endless resources and destroy it.

Revan Returns to the War

Revan was enlisted as a soldier in the Republic army and placed under Bastila's command on the Republic warship Endar Spire. Malak, thinking his master dead, devoted all his forces to the hunt for Bastila. In orbit over the world of Taris, the Endar Spire was attacked by a Sith fleet and destroyed. Bastila managed to escape to the planet's surface, followed soon after by Revan and fellow Republic soldier Carth Onasi.

Finding Bastila a prisoner of the Black Vulkar swoop gang, Revan staged a bold and harrowing rescue, then quickly escaped from the planet aboard the Ebon Hawk, along with Bastila, Carth, and the crew they had gathered on the planet. Even as they escaped Taris, Malak's fleet began a planetary bombardment, desperate to kill Bastila by any means. The Ebon Hawk fled to the Jedi stronghold of Dantooine, where Bastila convinced the Jedi academy council to retrain Revan in the ways of the Jedi. After completing his formal training, Revan took Bastila and, while investigating a structure of ancient ruins, uncovered the same Star Map he and his apprentice had unlocked years before. Though the Map was incomplete, it pointed the way to its fellows. Only with the combined information of all five Maps, Revan discovered, could the location of a mysterious Rakatan artifact called the "Star Forge" be found. This would be the key to ending a war in which the Republic could hold out no longer.

Revan, Bastila, and their companions journeyed to these worlds, tracing the steps Darth Revan had taken years before. On each planet, the powerful dark side aura of the Star Maps had created perilous conditions that made access to the Maps difficult. Additionally, the crew of the Ebon Hawk found themselves hunted by Sith and bounty hunters, and confronted with the problems of the local populace at every turn.

After discovering the third Star Map, Revan and his allies were captured by the Sith. They managed to escape from their holding cells, but, as they fled toward the Ebon Hawk, Revan was confronted by Malak, who revealed to him his former life as the Dark Lord of the Sith. A vicious lightsaber duel ensued, culminating with Bastila's capture by Malak. Revan was forced to deal with this Malak's revelation and his loss of Bastila as the quest for the Star Forge was stepped up, until at last it was found in the home system of the ancient Rakata.

After gaining the support of this race, Revan was forced to confront a fallen Bastila. Following weeks of torture at Malak's hand, Bastila had at last given in to her hate, fallen to the dark side, and become the Dark Lord's new apprentice (his original apprentice, a former Jedi named Darth Bandon, had previously been slain by Revan during the search for the Star Maps). Atop an ancient Rakatan temple, Bastila attempted to entice Revan to reclaim his former title of Dark Lord of the Sith. This was the climax of the quest for the Star Forge, and it ended with Revan, once again, making a choice that would change the fate of the galaxy.

The Redemption of Darth Revan

(based on canon as cited by Lucasfilm)

Revan made the choice of a Jedi, rejecting Bastila's temptation. Enraged, Bastila retreated back to the Star Forge, but Revan and the crew of the Ebon Hawk pursued her as a Republic fleet commenced an assault of its own.

Aboard the Star Forge, Revan faced off against Bastila once again. After defeating her, he attempted to convince her to return to the light side by drawing on the powerful bond of love that had formed between the two during the course of their quest. Finally, Revan again confronted his old friend and apprentice Malak in an epic lightsaber duel as the assault on the Star Forge continued, the Republic fleet now no longer hindered by Bastila's Battle Meditation. During their duel, Malak continually sucked the lifeforce from Jedi held in stasis to replenish his energies, but even this was not enough to defeat Revan. At last, Malak was slain, his life ending in darkness and regret, and the Star Forge was destroyed.

A year after the defeat of Malak and the collapse of the Sith Empire, Revan was left the Republic, having remembered the remnants of the ancient Sith Empire he had rediscovered as the Dark Lord and hoping to put an end to the threat it posed before it could attack the weakened Republic. Before he left, Revan bade farewell to the nine comrades who had accompanied him on his quest, knowing that, in the places he had to walk, none whom he loved could accompany him. He entrusted Carth Onasi with the Republic's safety, left the fearlessly loyal Mandalorian Canderous Ordo on the Outer Rim, and said goodbye to Bastila, his one true love. "It would have been better," Kreia, Revan's former Jedi Master, would later remark, "if he had made her understand. But she was always strong-willed, that one, and did not understand war as Revan did." Then Revan disappeared, leaving the Ebon Hawk with the droids T3-M4 and HK-47 on the edge of Known Space, for he knew he would not need them where he was going. If Revan ever completed his self-appointed mission and returned to the Republic and his waiting friends is unknown.

Repercussions of the War of the Star Forge

The Jedi Civil War devastated the Republic and rendered it vulnerable to another attack. Revan had believed this would come from the ancient Sith and gone off to prevent it. In his absence, the next threat to galactic security revealed itself. It struck not from the Unknown Regions, however, but from the shadows. In the heart of the Trayus Academy, the Trayus Core, on the ancient Sith world of Malachor V, an unholy alliance had been forged between Darth Nihilus and Darth Sion, former apprentices of the Sith Lord Darth Traya. Their new Sith possessed the ability to feed on the Force itself, something Nihilus had learned at the apocalyptic Battle of Malachor. Striking from the shadows, the new Sith killed with only one goal in mind: the complete and utter destruction of the Jedi. They twisted events and planetary situations, causing local conflicts on key Republic planets. These worlds, if left to fall, would mean a quick, destructive end to the Republic. A Jedi Exile, however, was about to return to prevent this . . .