Wars of the Dead
Wars of the Dead is a set of military campaigns in the Realm of Shyish, the first in the Age of Myth and the second in the Age of Chaos, and a third in the Age of Sigmar. In each case, Nagash seeks to drive off all rivals to his mastery of the realm.
Age of Myths
Nagash and his Mortarchs campaign to bring all of the Realm of Shyish under the dominion of the Great Necromancer. Those who dwelled in that realm were given the stark choices to flee, perish or acknowledge Nagash as their god.
Age of Chaos
Weakened by the War of Heaven and the Underworlds against Sigmar and subsequently the War of Bones against the Skaven, Nagash and his followers fought an increasingly desperate battle against the forces of Chaos. Finally the Great Necromancer was slain by Archaon at the Battle of Black Skies, his undead armies confined within the Cage of Bones and his stronghold of Nagashizzar reduced to a blasted crater.
Age of Sigmar
The regenerated Nagash and his armies burst from the underworld of Stygxx and destroy the forces of chaos there. Aid unlooked is received by the undead at the Arch of Bones and at the siege of Nulahmia where the Stormcast Eternals prove mighty allies.