Cleansing of Serenno The Cleansing of Serenno occurred shortly after the end of the Clone Wars , when Darth Vader drove the heirs of the Great Houses of Serenno to mass parricide . As a result , the Great Houses were brought in the bosom of the newly formed Galactic Empire , and Adan Dooku was appointed Count of Serenno , liege lord of all the other patricians on the planet . Most of the galactic community never knew what really happened on Serenno that day , only that the event had seen the replacement of the old heads of houses by their sons . Agent Jahan Cross of the Imperial Intelligence was one of the few to ever learn the true story of the Cleansing of Serenno , which he heard in 3 BBY from the mouth of Count Rodas Borgin , who had drawn the first blood during the massacre . History . Prelude . In the fifth month of the year 22 BBY , a war erupted between the Galactic Republic and the Confederacy of Independent Systems , a separatist union led by Count Dooku of Serenno . That conflict , known as the Clone Wars , raged on for three years , destroying the lives of many and ravaging planets . In deepest secrecy , both sides of the war were manipulated by a Sith Lord named Darth Sidious , better known as Palpatine , Supreme Chancellor of the Republic . Moreover , Dooku had been Sidious ' apprentice for about ten years , under the alias of Darth Tyranus . Toward the end of the conflict in 19 BBY , Palpatine was ready to transform the Republic into a First Galactic Empire in his image . Dooku of Serenno , leader of the Confederacy and secret Sith apprentice , was sacrificed by his master during the Battle of Coruscant . He was replaced by Anakin Skywalker , a fallen Jedi Knight who ultimately became the black - armored Darth Vader . The cleansing . Shortly after the end of the establishment of his Galactic Empire , the self - proclaimed Emperor Palpatine sent his new apprentice , Darth Vader , as an official representative on Serenno . The current heads of the planet ' s Great Houses had been summoned along with their oldest sons , and they were asked to meet Vader in the chambers of the Great Assembly House . Once the meeting had begun , the Emperor ' s right - hand man accused the assembled nobles of treason for having supported the Count Dooku of Serenno , who led the Confederacy of Independent Systems during the Clone Wars . The nobles all protested , but their shouting was to no avail . As a way of " cleaning " the Great Houses of Serenno , Vader announced that each heir of a given house would be anointed head of the family on the condition that they killed their own father . Initially , the nobles all protested again , but the young Rodas Borgin drew the first blood by stabbing his father . Following the shock of this first murder , there was a brief moment of silence , until the heirs of the other noble houses lost all hope of getting away alive if they did not comply . Brutally , a slaughter began , with all the young nobles committing parricide in the Assembly House . When the massacre ended , the new heads of the Great Houses pledged allegiance to their liege lord , the Count of Serenno Adan Dooku . He had been spared only because he had been raised away from his homeworld for most of his childhood . Aftermath . What really happened on Serenno that day was not revealed to the wider galactic community , and most people only knew that the old heads of houses had been " dismissed " in favor of their heirs . Years later , the Imperial Intelligence agent Jahan Cross was assigned to ensure that an older Rodas Borgin would be appointed as regent , since the heir of House Dooku , a boy named Bron , was only ten years old at the time . It is only when he met Borgin for the first time that Cross learned the truth about the Cleansing of Serenno .