Overview
The Thiravos-Theryssa Civil War was an ancient conflict between Thiravos and Theryssa during the collapse of the Malverand Empire. Remiella's wave-shard spell shattered Thiravos and Theryssa during the Fall of Malverand.
Background
Remiella led thousands of colonists to the continent of Thiravos and its northern region, Theryssa. The lands thrived under her water-and-earth magic and the wave shard. Tensions grew until unrest broke out between the two regions.
Open civil war between Thiravos and Theryssa began after Barachiel's disappearance. Remiella returned to stop the Thiravos-Theryssa fighting and refused Eremion's offer to send an army to spare those soldiers.
Catastrophe
Remiella poured the wave shard's power into separating Thiravos and Theryssa. The spell shattered the lands into smaller islands scattered across the sea. The shock also devastated northern Malverand: coastal cities were destroyed, the tsunami reached deep into Blackcrag, Maraveth's coast was affected, and millions died.
The wave-shard spell killed Remiella through essence overload. Nerissa manipulated Remiella into the fatal overload so she could free Thiravos and Theryssa from Malverand's control and seek a new wielder. Michael grouped Remiella's overload with Eremion's brutality, Jeremiah's secession, Uriandel's allegiance to Abraxas, and the spreading darkness as signs that Malverand had effectively ended.
Aftermath
Remiella's wave-shard spell left Thiravos and Theryssa as island nations isolated from mainland politics. Their societies worship Nerissa, remember Pyragos's later stabilization of the lands, preserve Malverand-derived language, gates, skyships, and essence-engine technology, and regard the old empire as a force they escaped.