Are these sentences worded in the proper way?

FYI- Szass Tam is the lich and Bezantur is a city in the province of Priador. Meanwhile, Szass Tam decided that since his fellow mage-lords had refused to elect him regent, he would withdraw from the Council of Zulkirs and use force of arms to become Thay’s supreme ruler. The lich secretly commanded the legions of Gauros and Surthay, newly augmented by a massive infusion of undead warriors, to march south to Bezantur, since if his forces took the city, he would essentially control the entire southern part of the country and all access to the sea. Bezantur and all of Priador were in a vulnerable condition at that time due to Aznar’s recent death and the commander of the province’s armies being assassinated on Szass Tam’s orders.