"So everything was connected like that…"
Thinking back to the events that transpired right before and during Fen's escape from the empire, it was no surprise that his shenanigans pushed some people to extremes. From how a royal was present on the arena during the fights, through how inquisition had to be irked by the appearance of a phoenixian right behind their backs, one thing added to another and resulted in something that Fen didn't expect even in his wildest dreams.
The sheer fact that they were the ones initiating the problems in Kiznar which directly ended up with Shalia falling in a state where only war could save its government from a total collapse might be a factor in the situation in the empire escalating just as well.
After all, with most of the major neighbours of the empire now busy with their own wars, both rebels and the royal loyalists didn't need to bother with potential outside interventions.