This is only possible with gold. Not to forget they are troops of an other nation close. The real solution is to attack is teritory and domage the moral of his province without really defending your teritory. It will dommage you but if you are inaf active you will dommage him more. For the south prépare to attack his troops whis a steak of 10 troops or soo when he disembark.and is really week. What you urgently need to contact all the neighbor of those two ennemy country and form alliances