No. Wall them off, and let em rot from within. Prevent any rats from leaving, allow the conservatives to leave after being fully compensated for all property and assets.
It’s a well-worn tactic in modern city sieges such as the post-Yugoslavia conflict. It doesn’t take that many troops to blockade a city, build fencing and barriers and maintain a few check points. Nothing gets out or in that isn’t approved and controlled. It was very effective at bleeding cities dry of all valuables, in effect looting as the residents went hungry. They brought the valuables to their besiegers.