The Grand Chancellor is a relatively new position, having only existed since the reign of Kasch IV, roughly 100 years ago. Kasch IV was more concerned with warfare and expanding Korpesh‘s territory (or, failing that, endless war games), and so he created the position to basically run the day to day bureaucracy of the country. The role technically only has power in the event of war or times of emergency, but the former Grand Chancellor, Sal Ormin, effectively ran the country during the twilight of Hator I’s reign.
Sal, under the influence of the mysterious tar entity, attempted to lead a rebellion against the king. He ended up dead in the gutter, likely assassinated by the Kalbs.
The King has not announced plans to fill the position.