In an abrupt turn of fate, Caorran was gripped by the sudden onslaught of a Slumberblight Pandemic. The formidable Houses of Rivacheg, Kastroya, Drachenfels, Quelius, Atreides and many more, all succumbed to the virulent disease within a span of mere months. Tragically, House Bardach, too, was not spared from the merciless grasp of the affliction.
In the wake of the King's unforeseen slumber, Duke Cailean Cousland of Gallaran ascended to the throne. Having previously served as the Kingdom's Chancellor, with marital ties to the royal family through his union with Princess Margaret Bardach and familial connections as the grandfather of one of King Eoghan's heir, Duke Cailean ascended to the throne, taking on the regal mantle as King Cailean I, a title that would later echo through the annals of history as King Cailean the Undying.
Facing the devastating Slumberblight Pandemic that had befallen most Caorrani Houses, King Cailean I perceived it as a divine retribution for Caorran's lack of faith. Despite adhering to certain spiritual customs, the Caorrani people had long abandoned religion. The ancient Caorrani rites, once integral to their way of life, had faded into obscurity, replaced by customs reflecting cultural values rather than religious convictions.
Determined to protect his people from further calamity, King Cailean I recognized the need for a robust religious foundation. On the date of 37-26-3, he, alongside Duke Avalon Hope, converted to the Aeternum Solis. Together, they oversaw the mass conversion of the Caorrani people, placing their faith in the Eternal God to shield them from future catastrophes.
The majestic Cathedral of the Sun was erected in Àirde, serving as both the seat of the Caorrani Cardinal before the Ecclesia and the primary religious temple of the Kingdom. Simultaneously, his esteemed kin, Rhiannon Cousland, received the distinguished appointment as the Cardinal of Caorran, despite her young age.
In the aftermath of the conversion, the Holy Caorrani Order of Bright Custodians assumed a central role directly under the Solar Ecclesiarch, acting as the Honor Guard for the Ecclesia. The Bright Custodians would also establish their own Duchy, complete with lands and vassals within The Ecclesia, following the successful campaign against the slumbered Raetia under the leadership of First Custodian Lachlann Cousland.
To formalize this significant shift, King Cailean the Undying enacted the "Official Recognition of the Aeternum Solis Act" on 37-37-3, designating the Aeternum Solis as the official religion of the Kingdom.