Mon Cala Mercantile Fleet

In 18 BBY, Admiral Raddus utilized at least five Star Cruisers and many smaller vessels as part of the defense of Mon Cala's southern hemisphere. Raddus grouped the vessels, and linked their shields, creating a large shield that repelled various attacks by Imperial submarines. Moff Wilhuff Tarkin began bombarding the planet, destroying many underwater settlements. Raddus kept the fleet in place while the bombardment targeted only the northern hemisphere. As the conflict on Mon Cala began drawing to a close, Lee-Char ordered the entirety of his forces to ceasefire. Raddus refused his command and when Tarkin's bombardment began targeting the southern hemisphere, he ordered the cruiser's to de-link their shields and run the Imperial blockade. The five cruisers complied and made a swift escape, losing two in the process. Tarkin let the final three go, stating that they would be found eventually.

After the Battle of Yavin, the Rebel Alliance approached Grand Admiral Dors Urtya, the commander of the fleet and regent of Mon Cala since King of Mon Cala Lee-Char had been imprisoned. In desperate need of a navy to take the war to the Empire, they wished to militarize the fleet by refitting its cruisers into warships, but the Mon Calamari were reluctant to use such action as long as their king remained a prisoner. After the initial failure to convince the Mon Calamari, Princess Leia Organa observed the fleet as the Millennium Falcon left the planet's orbit.

Believing that the Mon Calamari would be convinced to an alliance, the rebels successfully infiltrated the king's prison on Strokill Prime when they discovered that Lee-Char was only kept alive by life support systems. The dying king recorded a final message to his people, encouraging them to oppose the Empire's atrocities before he was killed by stormtroopers attempting to stop the rebels. The rebels then returned to Mon Cala where Urtya took the recording from them. After retrieving the recording, Urtya broadcasted the message to the fleet captains of the fleet, and the Mon Calamari crews witnessed their king's final message and his death at the hands of the Empire. Upon witnessing Lee-Char's final words and death, the Mon Calamari crews mutinied against Imperial personnel onboard.

Because the message was sent prematurely and the Mon Cala were not prepared nor supported, Imperial Navy forces led by Admiral Tyrus Meori, quickly responded and blockaded Mon Cala. However with the help of arriving rebel ships, led by Admiral Gial Ackbar, the Mercantile Fleet was kept from destruction. Captain Pysk Lila of the Aurora Flare contacted Ackbar asking how they could help. Ackbar told Lila to sacrifice her ship by charging at the blockade. Lila did so and Meori thought it was a desperate move until he realized the ship was loaded with coaxium intended to be taken to the Redhurne system. Lila's ship detonated and broke the blockade, allowing the other ships to escape. In total, the Alliance received twelve new ships from the Mercantile Fleet during the mutiny.

Kieron Gillen said in an interview that the idea for the Mercantile Fleet came from the need to explain how the Rebel fleet had suddenly grown between the events of Rogue One: A Star Wars Story and those of Return of the Jedi. He imagined a similar story to the post-Second Punic War situation of Carthage; although Rome forced them to demilitarize, they were allowed to continue trading and this allowed them to quickly settle the war reparations that they owed. Gillen said that he developed a similar backstory for the Mon Calamari living under Imperial occupation, but still possessing a large trading fleet which allows them to pay back their debts to the Empire.

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