The Genocide on Dac was an effort initiated by Darth Krayt, ruler of the Sith Empire and Dark Lord of the Sith, to eliminate every single member of the Mon Calamari species as punishment for their aid to the Galactic Alliance Remnant during the Second Imperial Civil War.
When Darth Krayt seized control of the Imperial throne, he immediately set his servants about to purge the Galaxy of his enemies. One of the most prominent enemies was the Galactic Alliance Remnant, led by Admiral Gar Stazi. Darth Azard was the Sith who was assigned to oversee the Remnant's defeat. He assigned Admiral Sha Dun of the Outer Rim Third Fleet to do so, and later Admiral Dru Valan when Dun was executed for his failure.
Valan laid out a trap for Stazi: he would lure Stazi and his fleet to the planet Dac where a new Star Destroyer was being constructed, the warship being the bait. However, the battle that happened was a disaster for the Empire: the Imperial fleet was decimated, the new warship was stolen, and the Remnant escaped with incredibly minute casualties.
Darth Krayt and Darth Wyyrlok walk away from the initial stages of the genocide.
Following the defeat of the Imperial fleet, Darth Krayt personally traveled to Coral City, Dac's capital, and summoned the Mon Calamari Council before him. He announced that he had had enough of the Mon Calamari's support of Stazi and the Alliance, and decreed that their entire species would be punished, with ten percent being executed immediately while the rest would be placed on forced labor camps until every single Mon Calamari died. Immediately, Emperor Krayt's loyal stormtroopers and Sith Lords began to attack every Mon Calamari on sight, and killed those Quarren that opposed them as well.
After Darth Krayt left the planet, Darth Azard, a Quarren Sith, was left to oversee the genocide with the aid of Vul Isen, a Force-sensitive Givin scientist also serving the Sith. By the time the genocide was displayed across HoloNet, ten percent of the Mon Calamari on Dac had been murdered.
While thousands of Mon Calamari were sent to extermination camps, where they were left without food or medical aid so they would die of disease and starvation, others fled to the deep oceans of Dac, where they were hunted down by the Imperial Army. However, the Mon Calamari Rangers rose to fight against the Imperial onslaught with the aid of Master Treis Sinde, a veteran Imperial Knight. Meanwhile, the Sith unleashed their latest creation, a Sea Leviathan, to enforce Emperor Krayt's edict. However, despite its destructive power, being capable of massacring an entire camp in a matter of minutes, the Leviathan was eliminated thanks to the efforts of Master Sinde and the Rangers.
The Galactic Alliance's Rogue Squadron staged a mission to rescue a group of Mon Calamari refugees by using cargo carriers to evacuate them. When bounty hunters working for the Sith tried to track the refugees to Stazi, the Rogues managed to lead them in the wrong direction by defending the wrong cargo carrier.
The dead following the Final Protocol.
A short time after the death of Darth Krayt, Lord Wyyrlok, Voice of the One Sith and the new ruler of the Empire ordered Vul Isen to execute the Final Protocol, and poison the waters of Dac to wipe out all life on the planet so Imperial forces could be deployed elsewhere. Lord Wyyrlok paid little interest to Lord Azard's reminder of the Quarren collaboration and the neutrality of individuals of other species, ordering that they would be allowed to escape the planet but would receive no aid. Isen released viral spores which, carried throughout the planet by oceanic currents, would eliminate all life in a single week.
Three days after Wyyrlok's edict, Rogue Squadron executed a recon mission on the planet and were shocked to discover a section of the ocean covered by a mass formed by millions of bodies of dead Mon Calamari and Whaladons. They immediately set out to inform Admiral Gar Stazi, though Andurgo broke formation and began to fire on incoming Predator fighters.
When Stazi heard of this, he chose to save the Mon Calamari. His fleet returned to Dac and, after fighting off both waves of Sith-Imperials that came after him, managed to rescue a portion of the planet's population. Although it numbered in the millions, it was only a small portion of the planet's 27 billion inhabitants.
Krayt intended to accomplish two objectives with the genocide: punish the Mon Calamari and dissuade further opposition to his empire.
However, while it did force some systems into submission, many other planets and systems were outraged. These systems "allowed" ships from their planetary fleets to join the Galactic Alliance Remnant, while many Mon Calamari that were off world at the time joined the Remnant. These increased Stazi's forces substantially.
The poisoning of Dac, which claimed billions of lives, also inspired more people to fight against the Sith Empire as well as destroying the diplomatic relations with the empire and its neighbors, the Chiss Ascendancy and the Hapes Consortium (who refused to even speak with Sith-Imperial representatives after the poisoning was announced). The subsequent devastation of Da Soocha and Napdu also led the Hutts to join the efforts against the Empire.
- Legacy Era Campaign Guide