Novian War
Military action
Karthian colonies on Itirria - called Novia by Karthians - finally secede from Oligarchy, forming their own country - Republic of Novia.
the longterm negative thoughts caused by lack of help from Karthia during the Devourer rampage - combined with the already existing mutual dislike - finally sparks war.
Civil war in Karthia is brief and ends with Novian succesfull secession.