How much good can the might host do?

As far as I can tell the best that the might host could do would be to force the Charisians back into the various mountin gaps where Charis will be able to use their longer range artillery to nuterlize the MH artillery beyond theMH artillery range. Also if Charis is forced back into the gaps then I see no way that the church could force them out except with mass attacks and that would be a disaster for the church. Also if they are forced back into the gaps then Charis should be able to decvelope a steam powered AFV and use that to break the stalemate but the church would not be able to do that. Also even if Charis is forced back into the gaps they could always launch an amfibious invasion of some other realm to far away from the MH for it to be able to stop them. So what can the church do to actually use the MH to force Charis out of Siddarmark?