The Corellian Treaty served as the foundational agreement that gave rise to the Alliance to Restore the Republic. This agreement, signed by prominent leaders of various anti-Imperial resistance movements hailing from Alderaan, Corellia, and Chandrila, officially marked the beginning of their war against the Empire. While Galen Marek played a role in arranging the meeting where the treaty was created, it was later revealed to be a cunning trap orchestrated by his former master, Darth Vader. Vader led a Stormtrooper Corps assault on the meeting, resulting in the capture of the three senators. If Galen had not survived his confrontation with his former master, the Empire would have effectively crushed the Rebellion before it could truly take hold.
Having successfully unified the resistance forces on Corellia under a single command, Garm Bel Iblis extended an invitation to Bail Prestor Organa of Alderaan and Mon Mothma of Chandrila. These individuals had previously engaged in discussions about potential revolution during the Cantham House Meetings. The purpose of the invitation was to convene a new series of discussions on Corellia. These subsequent Corellian System Meetings yielded more fruitful results, leading the three resistance leaders to draft the Corellian Treaty. This treaty served as a formal declaration of their shared ideals and objectives. With the signing of the treaty by Bel Iblis, Organa, and Mothma, the relationship between the Corellian, Alderaanian and Chandrilan resistance forces transformed from a loosely connected coalition into a well-organized rebellion.
The treaty itself outlined a command structure for the Alliance, designed to grant each force autonomy while establishing a robust central authority to coordinate overall efforts. It organized civil functions, including diplomacy, transportation, and supply, into a unified structure, while consolidating all military operations into another. The Commander-in-Chief and Advisory Council were placed at the apex of this structure. Organa pledged to provide funding for the rebellion, Bel Iblis committed to supplying ships for its fleet, and Mothma offered to contribute soldiers.
The treaty, suggested to Marek by Darth Vader, was in reality a scheme devised by Emperor Palpatine to lure all of his adversaries into a single location for capture. Just as Bail Organa announced the treaty's finalization, Imperial forces launched a sudden assault on the building. As Stormtroopers stormed into the meeting room, eliminating all the guards, Bail instructed PROXY to sever Leia's transmission in order to conceal her involvement.
As PROXY complied, Darth Vader entered the room, ordering the troopers to capture the Rebels alive for the Emperor's personal execution. Kota immediately ignited his lightsaber and charged at Vader, but the Sith Lord effortlessly subdued him with a Force grip, throwing him aside. As the stormtroopers rounded up the Rebels, Vader approached Marek and praised his performance, revealing to the astonished Rebels the "Jedi's" true allegiance as his apprentice, before using telekinesis to shatter the stone table in the room into Marek.
Marek was propelled out of the meeting room and onto the snow-covered cliff ledge surrounding the building. As he struggled to regain his footing, he angrily confronted Vader, questioning his presence, as he had agreed to stay away. The Sith Lord responded that he had lied, as he had done so from the very beginning. Realizing that "the very beginning" referred to the start of his apprenticeship under Vader, Marek understood that Vader had no intention of destroying the Emperor—not with him, anyway. Vader used the Force to seize Marek and hurl him over the cliff, though Marek managed to grasp the edge. Marek looked up at the advancing Vader, calmly declaring that Vader would never be free without him.
As Vader raised his lightsaber to finish Marek, he was suddenly attacked from behind by what appeared to be Obi-Wan Kenobi, Vader's former Jedi Master. Briefly caught off guard, Vader was forced back a step. However, he quickly recovered, blasting Kenobi back with a Force push and impaling the Jedi before he could recover. "Kenobi" suddenly dematerialized, revealing himself to be PROXY utilizing his Kenobi combat module. The holodroid fell to the ground, his last word being a call to his master, distorted by his failing computers. Vader kicked the droid lightly to check if he was subdued, and satisfied that he was, turned back to the cliff.
However, Marek was gone, having lost his grip and fallen while Vader had dealt with PROXY. Vader deactivated his lightsaber and rejoined the troopers within. However, Marek had survived his fall, and was rescued by Juno Eclipse. Resolving to pursue Vader and rescue the Rebels, Marek used the Force to locate their ultimate destination; the Death Star.
The three senators and Kota were brought before the Emperor himself, who gloatingly announced that they would be subjected to torture, interrogation, and ultimately, execution. However, before Palpatine could dispose of the Rebels, Marek arrived and confronted Vader and Palpatine. The Jedi almost killed Vader, but lost his life confronting the Emperor after nearly killing him as well. Thus, he still bought the time for the Rebels needed to escape.
Later, after Marek's death at the hands of Darth Sidious, the Anti-Imperial Senators returned to Corellia and revived PROXY. Afterwards, Leia convened with Bail Organa, Mon Mothma, Garm Bel Iblis, Rahm Kota, Juno Eclipse, and PROXY on Kashyyyk, forming the Rebel Alliance. Leia selected a symbol for the Alliance, the symbol of the Marek family, as a tribute to Galen Marek, his family and his victories against the Empire, and so began the Galactic Civil War.
A key provision of the Corellian Treaty stipulated that upon the death, resignation, or overthrow of Palpatine, the position of Chief of State would be abolished. Instead, a Constitutional Convention would be mandated to deliberate on the structure of the restored Galactic Republic.
The Corellian Treaty, which is the foundational document of the Rebel Alliance, was initially presented in the roleplaying book titled The Rebel Alliance Sourcebook (published in 1990) and has since been referenced in various other sources. However, the specific circumstances surrounding the treaty's signing and the Alliance's formation were not fully detailed until the release of the 2008 multimedia project Star Wars: The Force Unleashed. For the purposes of The Force Unleashed, certain implied and explicitly stated details were altered, including the motivations of the founders.