BoM was a distraction for the south. So long as they were united and "strong" there were members of the League much more interested in killing BoM. With BoM dead, the entire league can focus on wiping Darka off the map. It doesn't matter how strong they are. With 100 nobles they couldn't win this war. They don't have the cs, they don't have the moral support of anyone at this point, and they're completely surrounded.
