Complex sentence: Gadu, who was a former captain of the guards of King Ram Khamhaeng of Sukhothai, had decided to seize the governorship himself, and had ordered U Yaing to bathe in the river where Aleimma would see her.
Split into simpler sentences: Gadu, who was a former captain of the guards of the king of Sukhothai, had decided to seize the governorship himself. Indeed, it was Gadu that had ordered U Yaing to bathe in the river where Aleimma would see her.