The alchemy contained within a small watch led Mage Miler to view Thunderous Swamp as a threat to Cloud Tower's authority.
However, a mere secular minor power was not enough to warrant Cloud Tower's personal involvement. Doing so would only elevate Thunderous Swamp's status, which would be quite embarrassing for Cloud Tower.
Since the group of alchemists hidden within Thunderous Swamp had chosen Eternal Domain as their representative, Miler chose Marquis Anderson as his enforcer.
As long as Marquis Anderson conquered Thunderous Swamp, it would prove Cloud Tower's alchemy was superior to that of Thunderous Swamp without Cloud Tower having to intervene personally, thus securing both reputation and substantial benefits.