This entire thing does not make sense. With as close the village was to Elturel and with how important the trade link link between Elturel and Baldurs Gate was, Ketheric would never have been able to raise an army and instead would have been anihilated by Hellrider and/or Flaming Fists instead of an Harper-druid alliance
This took place a hundred years ago.
There's a letter in Moonhaven talking about Elturgard and how the locals weren't friendly to the idea of folks from Elturgard trying to encroach on them. Elturgard was presented as somewhat fledgling in nature, and the locals considered themselves free of far away lords who would tax them. It leaves me with the impression that you might be overestimating the provincial value of Elturgard during the time period in question.