The Amberikon Crusade (pronounced am-BEAR-ih-con) was an almost five decade long war fought by the combined forces of the nations around the Sea of Ersas and western Thadria against the demons that began to emerge near the city of Amberikon in Y7550*.
Following the destruction of the Amberikon era clock in Y8550*, planar boundaries between the Material Plane and the Abyss intersected in eastern Thadria. This provided a means for creatures from either plane to pass into the other, something the demons of the Abyss began to do in significant numbers. The city of Amberikon and surrounding communities were quickly overrun before the demons began to appear elsewhere along the western coast of Thadria.
The Amberikon Crusade was called in Y8551*, an effort by the Iomadean clergy to counteract the demonic invasion. The Stronghold of the Light was quickly constructed on the formerly sparsely inhabited island of Mesollonia to serve as a base of operations and staging grounds for the crusaders arriving from across the world.
The fighting lasted for decades as the demons proved difficult foes. The crusaders were consistently one step behind, as the extraplanar invaders appeared unpredictably. These small groups of demons may have been easier to counter individually than a single large force, but combined they were a great threat. Only when the planar rifts began to be sealed did the tide turn back in favor of the crusaders.
In Y8596* the Amberikon Crusade was declared victorious as the last of the major rifts were sealed. Smaller rifts and some demons would exist for longer, though drastically reduced in threat. The Stronghold was maintained as a monument to those that fell in battle and as a holy site to Iomedae.