From the Setting Guide

Mornburg is a city steeped in bloodshed. It was at the center of the Mendax Rebellion, where a cult dedicated to Mendax the Defiler gained power and influence in the city and turned the city into a hellscape of corruption and death.

The rebellion was ended by the Order of the Silver Gauntlet, who spent almost a decade rooting out the corruption in the city before making it the base of their organization.