The Mon Calamari Resistance, operating against the Imperial regime, was a movement spearheaded by Gial Ackbar alongside influential members of the Mon Calamari Council on their homeworld, Mon Calamari, during the initial stages of the New Order. Subsequently, it evolved into a pivotal component of the Alliance to Restore the Republic.
Within months of the Galactic Empire's establishment and the implementation of its New Order, Imperial forces initiated the subjugation of significant non-human planets. Kashyyyk was among the first to fall, succumbing almost immediately after the conclusion of the Clone Wars. The Empire recognized the technologically advanced planet of Mon Calamari, renowned for its expansive shipyards and abundant mineral wealth, as a highly desirable asset. This ambition was further fueled by the intention to exploit the indigenous Mon Calamari and Quarren populations as a source of slave labor. The Imperial administration anticipated that seizing control of the planet and its shipbuilding facilities would substantially bolster their military capabilities, thereby weakening the Tion Cluster and suppressing any anti-Imperial sentiments along the concluding section of the Perlemian Trade Route.
Following the failure of the Mon Calamarians' attempts to achieve a peaceful agreement with the Empire, a faction of disgruntled Quarren deliberately deactivated the planet's protective shield network upon the arrival of an Imperial fleet. Caught off guard, the planet was swiftly overtaken by Imperial forces. Both Mon Calamarians and Quarren were subjected to enslavement and forced labor, with their resources diverted to fuel the expansion of the Imperial war machine.
The initial phase of Mon Calamari's opposition to the Empire was largely characterized by non-violent methods. For nearly two decades, the Mon Calamarians and Quarren engaged in acts of sabotage against equipment, deliberately caused delays in industrial processes, and organized protest movements. Gial Ackbar, a Mon Cal naval officer and a member of the Calamarian Council, laid the groundwork for what would eventually become the resistance. Unfortunately, Ackbar was apprehended and became the personal slave of Grand Moff Wilhuff Tarkin. The Empire's initial response involved a large-scale propaganda campaign, during which sentientologist Obo Rin published works asserting that the planet had been discovered by Imperial scouts. These efforts aimed to diminish the planet's centuries-long association with the Old Republic. When the Mon Calamarians and Quarren persisted in their resistance, the Empire resorted to more forceful tactics to suppress dissent. An Imperial fleet stationed in the Calamari Sector initiated an orbital bombardment, resulting in the destruction of three floating cities.
Rather than suppressing the resistance, this act ignited a full-scale rebellion among the planet's inhabitants. Following plans initially conceived by Ackbar and other key resistance leaders, Mon Calamarians and Quarren put aside their historical animosities and united in their opposition to the Empire. Initially, their weaponry was limited to kitchen utensils and tools. However, they soon began utilizing caches of weapons that had been concealed throughout the years of occupation. Imperial warships undergoing repairs at the shipyards were targeted for sabotage. Secret shipbuilding facilities, concealed throughout the Calamari system and beneath the planet's oceans, commenced the production of starships for combat. Mon Calamari privateers launched attacks against the sector's Imperial fleet. Faced with escalating losses and a significant uprising, the Empire withdrew its forces from the sector.
The victory of the Mon Calamarians and Quarren over the Empire served as a major source of inspiration for other planets across the galaxy resisting Imperial rule. Several years prior to the Battle of Yavin, Mon Mothma, the leader of the Alliance to Restore the Republic, successfully negotiated an agreement with the planet, securing access to its renowned shipyards. Despite this, the Mon Calamari did not formally align themselves with the new Alliance. Concerns regarding potential backlash from the Quarren due to an alliance with Human resistance groups led the Calamarian Council to refrain from becoming full members. Nevertheless, numerous Mon Calamari ships and crews joined the ranks of the Alliance. Warships from the Rebel Alliance Fleet were deployed to safeguard the sector, while the celebrated Ackbar became an unofficial member of the Alliance High Command.
In the wake of the Alliance's decisive triumph at Yavin, the Calamarian Council resolved to become fully integrated members of the Alliance. The planet emerged as one of the few openly pro-Alliance worlds in the Galaxy. Ackbar ascended to the rank of admiral and assumed the role of Supreme Commander of the Alliance Fleet Command. The planet's massive starliners and exploration vessels were repurposed into warships. These Mon Calamari Star Cruisers formed the core of the Rebel fleet. The unwavering dedication of the Mon Calamarians, in particular, to the cause of the Rebellion earned them the epithet "Soul of the Rebellion".