The Alderaanian Resistance, operating during the early years of the New Order, represented an initial opposition force against the Galactic Empire. This group was spearheaded by Bail Organa on the planet Alderaan. Subsequently, it played a role as a founding entity within the Alliance to Restore the Republic.
Palpatine's Declaration of a New Order at the conclusion of the Clone Wars sparked concern in Bail Organa, along with numerous other members of the Galactic Senate. Advised by Padmé Amidala, Organa chose not to openly confront the newly appointed Emperor. He instead chose to project an image of loyalty as a senator, thereby gaining access to crucial intelligence for any potential resistance effort.
On his native Alderaan, Organa initiated the recruitment of individuals to support his cause, including the Caamasi Jedi Ylenic It'kla, and the noblewoman Lady Alya Aldrete along with her smuggling operation. Furthermore, he made certain that his adopted daughters, Leia and Winter, received intelligence training. Despite Alderaan's post-Clone Wars abandonment of its military and its philosophical opposition to armed resistance, Organa understood the significance of emerging resistance movements such as the Nizon resistance and Corellian Resistance. He committed to providing non-combatant support, encompassing funding, technical assistance, and intelligence gathered by his organization.
He also cultivated various allies beyond Alderaan, including Jedi Master Denia and her associates, and achieved important victories, like the Battle of Nizon and the Battle of Byss.
Eventually, the Corellian Resistance came to understand the need to unify with other resistance groups to effectively challenge the Empire. Consequently, they dispatched Bria Tharen to engage with these other groups. Bail Organa consented to send representatives to consider the Corellians' proposals, dispatching Deputy Minister of Security Hric Dalhney, accompanied by Winter and Ylenic It'kla, for a meeting with Tharen in Cloud City. Dalhney, reluctant to compromise Alderaanian principles by involving his people in combat, agreed only to continue the existing support. However, Winter found Tharen's arguments convincing and pledged to advocate for armed resistance to Bail Organa upon her return.
Organa, finally convinced of the necessity of armed resistance, initiated clandestine armament of his people, facing significant opposition from within his own government.
Bail Organa was eventually contacted directly by Garm Bel Iblis, his former colleague in the Senate and the leader of the Corellian Resistance. Across a series of meetings on Corellia, Organa, Bel Iblis, and Mon Mothma, leading the Chandrilan resistance, concurred on the necessity of formally uniting their movements. They then signed the Corellian Treaty, which served as the foundational document for the Alliance to Restore the Republic.