Long before Farhadi launched the attack, in fact, Kasam had already received the news. However, it was too late, with no time to react or devise a counter-strategy. In utter desperation, he left the capital city via a secret security passage, escorted by bodyguards, to temporarily avoid the disaster. As long as he remained, there was a good chance to crush Farhadi's conspiracy.
Farhadi had planted an insider in Kasam's camp, and Kasam did the same with Farhadi's camp.
However, by the time Kasam learned of this, Farhadi was already about to launch the attack, leaving them far behind in terms of timing.
In a situation where he had no choice, Kasam immediately left the capital, taking with him only a few loyal department leaders.
Indeed, Kasam was too important to Ba Country. As long as he wasn't captured, there was a chance of making a comeback.
Once captured, nothing could be done; this was an indisputable fact.