the SIEGE of Neverwinter

The city is ruled fairly and justly by Lord Nasher Alagondar, an aging, veteran adventurer and devout worshiper of Tyr. He dies during the SpellPlague that sweeps the land from its enemies...but also from its defenses. The SpellPlague is a curse that killed many - also a sickness that allowed the Undead to rise again.

Although Lord Nasher died during the Spellplague, he gave rise to a royal line that is believed to have ruled until Mount Hotenow erupted, destroying the already failing city. Two decades after the city's destruction, Dagult Neverember, Open Lord of Waterdeep, seeing an opportunity to add to his financial empire, hired artisans and carpenters to help rebuild the city and mercenaries to protect it from monsters; he would eventually create the title of Lord Protector of Neverwinter, held by Neverember himself. However, it is wrong to say that Dagult is the ruler as many factions vie for Neverwinter and the citizens are divided in loyalties.

Read more to learn what happened: http://forgottenrealms.wikia.com/wiki/Neverwinter