As a direct reactionary to the formation of the Galactic Empire, the Alliance insurgency conducted covert operations on Imperial garrison-worlds and guerrilla warfare against the Imperial Fleet throughout the Star Wars galaxy. While the Empire considers all rebellion as acts of extremism and terrorism in Imperial propaganda, the Alliance is described and portrayed in various Star Wars media as a resilient freedom fighters, one based on toleration, empowerment in diversity, insurgency weapons and tactics, and a hope for a better future.
The Rebel Alliance was first featured as the main protagonist-faction in the 1977 film Star Wars, The Empire Strikes Back (1980) and Return of the Jedi (1983). The faction's origins were alluded to in Star Wars: Episode III – Revenge of the Sith (2005), and their early activities are featured in the Disney XD television series Star Wars Rebels and the 2016 anthology film Rogue One.
The origins of the Alliance to Restore the Republic are told during the events of Revenge of the Sith. It is explained that the Delegation of 2000 is a group of Senators who are disgruntled about the already unjustified extraordinary powers of Supreme Chancellor Palpatine, as the Clone Wars were waning. The group included Bail Organa, Padmé Amidala, and Mon Mothma, amongst others. At the time, Amidala was the most famous and prominent of the group, and was thus their spokesperson. She realized that this made her a target and later advised the others to go quiet in their dissent and exclude her from any future proceedings. The young senator died in premature childbirth not long after her last-ditch attempt to prevent Anakin Skywalker's fall.
The TV series Star Wars Rebels, set five years before A New Hope and fourteen years after the fall of the Galactic Republic and the Jedi Order in Revenge of the Sith, begins with the rebellion against the Galactic Empire. The show focuses on a motley group of rebels (all of whom have been affected by the Empire in one form or another) that band together aboard a freighter starship called Ghost. By the end of the first season, it is revealed that there are various clandestine cell systems that are resisting the Empire. Senator Bail Organa of Alderaan and former Jedi Ahsoka Tano both play a pivotal role in coordinating these splinter cells into a legitimate threat capable of challenging Imperial rule. Funded primarily by the Royal House of Alderaan, the alliance began to allocate resources towards a united front against Imperial rule.
Near the end of the third season of Star Wars Rebels, one of the Alliance founders, Senator Mon Mothma, escaped assassination for speaking out against the Emperor. She calls out to the various rebel cells and insurgency factions to unite into a unified coalition:
We, the beings of the Rebel Alliance, do this day send forth this Declaration to His Majesty, the Emperor, and to all sentient beings in the Galaxy, to make clear to all the Purposes and Goals of this Rebellion.
We believe that the Galactic Empire has willfully and malignantly usurped the rights of the free beings of the Galaxy and therefore, it is our unalienable right to abolish it from the Galaxy. We, the Rebel Alliance, do therefore in the name—and by the authority—of the free beings of the Galaxy, solemnly publish and declare our intentions: