The Great War is a multinational (and to an extend, multi-planetary) conflict that has been in progress for between thirty and fifty years, depending on the given participants. The Prime Four are the main belligerents, but have drawn other nations from time to time, including Tanatha and Chibal.
There have been six armistices, but only four main ones. The First Armistice marked the end of Vaasith's hegemony over the Rahik system, and signalled its decline overall. Damamat benefitted greatly from the conditions of the cease-fire.