Imperial Civil War

The Imperial Civil War was a term given by the New Republic to two events.

Specifically, it referred to the conflict that erupted on Coruscant in 10 ABY. The various Imperial warlords, encouraged by what Thrawn had recently accomplished with so little in such a short amount of time, agreed to organize under the Imperial Ruling Council for an attack into the Galactic Core. The New Republic was no match for the military might of the once-more-unified Empire, and after a short and decisive campaign, the Empire had retaken its Center in the Third Battle of Coruscant.

However, after Coruscant had been retaken, the Council decided that it was time to elect a new Galactic Emperor. The various admirals, generals, and moffs disagreed, and an armed conflict soon broke out amongst the various Imperial factions on Coruscant. It laid much of the planet to waste, and was only ended when, several months after the retaking of Coruscant, Palpatine announced that he had returned.

In a more general sense, the New Republic also used the term "Imperial Civil War" to refer to the fratricidal series of conflicts that critically weakened the Empire between the aftermath of the Battle of Endor (4 ABY) and the purging of the last major warlords by Admiral Daala (12 ABY), resulting in the essentially-reunified (but much weakened) Empire.