Havael the Fleetfooted rebellion.

Western Army was fighting a prolonged war against barbarian tribes of central Itirria for years now, succesfully managing to to achieve significant territorial gains... that it, however, struggled ot hold.

  Whats more, during last years of Falon reign Novian government attempted to... gain control over them too, with imperial government didn't exactly reacting. It was finally enough.

  With Falon' death, the last source of loyalty for the Western Army (composed mostly of elves) was broken. Soon the army was practically independent... and waging war against Novian Republic.