The Mon Calamari Subjugation represents one of the initial military engagements undertaken by the newly established Galactic Empire. This conflict culminated in the enslavement of both the Mon Calamari and the Quarren species for approximately twenty years, until they collectively revolted and expelled the Empire from their planet.
Following the termination of the Galactic Republic, the nascent Galactic Empire commenced its expansion throughout the galaxy. As the Imperial military apparatus expanded, the need for additional resources increased. Enslavement became a crucial element in this expansion. Similar to the Wookiees of Kashyyyk, the indigenous Mon Calamari and Quarren inhabitants of Mon Calamari were considered ideal candidates for enslavement. Furthermore, the planet's extensive ship-building facilities and its proximity to the Tion Cluster rendered it an ideal location for an Imperial military installation.
The Mon Calamari attempted to negotiate a peaceful resolution with the Empire; however, their overtures were rejected. The planet was subjected to a full-scale Imperial invasion, commanded by Moff Wilhuff Tarkin.
Confident in the protection afforded by their planetary energy shield, the Mon Calamari and Quarren initially believed they could withstand any Imperial assault. However, a number of disaffected Quarren individuals sabotaged the planetary shields, thereby rendering the planet vulnerable to invasion. This group was led by Seggor Tels, a Quarren leader motivated by animosity towards the Mon Calamari. Consequently, the planet quickly fell under Imperial control, and the Mon Calamari Orbital Shipyards were seized by Imperial forces.
For nearly two decades, the Empire maintained control over Mon Calamari, despite the gradual development of resistance movements by both the Mon Calamari and Quarren populations. Experiments aimed at constructing Imperial warships utilizing Mon Calamari construction methodologies proved largely unsuccessful, and the resilience of the Mon Calamari people exceeded Imperial expectations.
Prior to his involvement with the Rebel Alliance, Admiral Ackbar was enslaved by Tarkin for an extended period during the Imperial occupation of Mon Calamari.
In its initial publication, The Star Wars Sourcebook depicted this battle as the initial encounter between the inhabitants of Mon Calamari and the broader galaxy. However, with the introduction of Mon Calamari and Quarren characters in the prequel trilogy and numerous Expanded Universe narratives occurring prior to the Empire's rise, this detail has been retconned.