C1140 Confrontation
The beastmen of the Beastman City were all criminals.
But they weren't stupid.
Therefore, when they believed the rumor of the upper echelons slaughtering the lower echelons, they chose to follow and attack the prison.
Of course, they knew that it was a serious crime in the Beastman City, but if the fact of the slaves fleeing in all directions gave them a chance to escape
