Initially, the Chapter of the Sun was unaligned with the Church of the Five, which was founded in Ethryke in 684 BC to unite the various denominations of Paragons faithful, but came to align with its beliefs; there was, at one time, an Archdiocese of Edrane that represented the Church of the Five more officially, but the Kingdom of Andoras dismantled this organization in 336 AC following the mounting tension between the nobles and the laymen, which, though the Pentarch nor the Caridrean Curia took kindly to, understood as a necessary move to protect peace in a turbulent time. The Chapter of the Sun took this as an insult and decreed that the Church had fallen out of favor with the Paragons themselves, claiming that only the beliefs of the Chapter could bring men to salvation, and that the Church had grown infested with the corruption of nobles and landed pentems using it to exude power over the poor. The chapter intended to declare independence, but this escalated into a conflict with House Tyseth, the lords of the realm, who sought to have themselves recognized before the faiths of their subjects. Threatened with the same fate as the Archdiocese, the Chapter rose up in rebellion, and embroiled Edrane in its bloodiest civil war to date.
The Chapter of the Sun started similarly to a cult during the Third Era, when The Five Paragons was still a shunned subject in Edranish society. It expanded slowly over hundreds of years, until it was recognized by the Crown and given permission to become an official organization. Thus, the Chapter of the Sun was formed, and Edrane had it's first official religious organization.
However, the Chapter's reputation in Edrane was one of mockery, as most believed it an organization for the naive or weak. They had next to no authority within the country and were sometimes persecuted among the middle class. Years of this treatment groomed hostility and resentment between the pious lower class and the agnostic middle and upper class, and the Chapter of the Sun used this disgruntled peasentry to barter for more rights.
As of the Eighth Era, the Chapter had it's own holy soldiers and royal sanctioned properties and cathedrals. It had grown more populous and influential, and despite the Chapter's divine intentions, it greatly abused this influence. When the Crown did something that the Chapter disapproved of, or refused a Chapter request, the Chapter would brew discontent and anger among the lower class. This often led to riots and minor revolts, forcing the Crown to step in with soldiers or submit to the Chapter's wishes.
Finally, when both House Tyseth and the Chapter of the Sun had enough of each other, the Crown decreed that the Chapter of the Sun needed reformation. Naturally, the Chapter rebelled against this idea and, to the surprise of the entire nation, organized the largest rebellion Edrane had ever suffered. Every member and follower of the Chapter was inspired into a blind zeal by the High-Divine, Wosol Kayn, who was seen as a warrior and a common man like the rest.
Spurred into open revolt, hundreds of thousands of the lower class were suddenly brandishing arms against the Crown all across the country, led by Chapter priests and directed into war. The Chapter used it's poorly trained but well-equipped army to burn settlements, seize castles, and execute entire noble houses, and for a time it seemed the upstart Chapter would find victory. It wasn't until the Army of the Sun made it back to Edrane that the Edranish Army finally found itself on the winning side, using the now superior numbers and training to push back the Chapter armies to the west, where they finally holed up in the once ruined Mudtalon Castle.
The Chapter's last stand, the Siege of Mudtalon Castle was the final battle of the Paragon's Revolt and the location of the Chapter's extinction. In 8E 338, Prince Dessar Tyseth led a grand siege against Mudtalon Castle with the goal of exterminating the Chapter and it's followers permanently. Lasting seventy-six hours, the siege had peaked and ended within the final four hours as disloyal Chapter members sabotaged the gates and allowed the Edranish forces to storm into the keep. In an act of surprising mercy, almost the entirety of the participating lower class that survived the rebellion were spared and sent home, while every Chapter official was thrown from the surrounding cliffsides.
The Chapter is looked back at with a terrible stigma, seen as evidence that religion brings conflict and instability. The ruling Prince understood that banning the religion would only bring more tension into the ravaged nation, and thusly the people of Edrane were simply encouraged to practice their beliefs among themselves at home. When the issue of organized religion is brought up in Edranish court, the Chapter is always referenced in opposition, and so far the matter has yet to gain any traction since the Chapter's dissolution.