So that Glacier did so much for war in Atamara...
The primary purpose of the glacier was never to directly increase or stimulate war.
Whatever changes in the political and military situations on the continents affected by the glaciers and the monsters came about because of the players' decisions. That is the way BattleMaster works.
In this case, from everything I have heard, the realms affected by the glacier on Atamara were too afraid to actually try to do anything about it, so rather than go down fighting, even if it meant their death at the hands of another realm, they just let the ice swallow them up.
