The Dukedom of Mousillon was a former founding Dukedom that once had territories stretching along the western shores of Bretonnia. Ever since its fall, Mousillon is a cursed, impoverish land that is plagued by constant misfortunes, disease and drawing the attention of dark powers. Having since lost its status as a proper Dukedom, the lands of Mousillon is the smallest out of all the twelve realms, even though it once held the title as being the most beautiful and fairest land of them all.
Ever since the death of the previous Duke, what remains of Mousillon is a backwater region filled with marshes, bogs and swamps. Those people still living within the Dukedom are inbred and horribly mutated. Mousillon villages look poor and rundown, more so than typical Bretonnian villages. The peasant hovels are on the verge of collapsing, streets are little more than sewers, and there are as many dead animals to be seen as living ones. The inhabitants watch any visitors silently from their homes, cowering within and giving only occasional glimpses of their malformed bodies. No one rules this accursed land, for none wish to do so otherwise.
Mousillon can be a worthy challenge for the Bretonnian factions wishing to remove the Vampires from their lands. The Corruption lingering in the lands as well as The Red Duke's shambling armies often guarding the city itself means a standard assault might be hard. To counter this, you could bring a character with Untainted, slowly removing the corruption from Mousillon. You could also force the Red Duke to move away from his city by raiding his lands, leaving the settlement unguarded.
Mousillon is geographically separated from the other Vampire Counts factions - it lies in the west, surrounded by Bretonnian factions. Mousillon starts out controlling the city and region of Mousillon within the LyonesseProvince. With the Aye-Aye! Patch, the faction The Barrow Legion got added to the Grey Mountains bordering Bretonnia. This means Mousillon's got a potential ally if it can survive the Knights of Bordeleaux and Lyonesse, aiming to purge the city of Undead.