The Ashes of Lothier
It was left to the Heroes of High Castle to defend the God Machine. Niccos and Kreldig led an army to stop Dagos from ascending. They succeeded, not knowing that Lothier had different plans. Lothier threw himself on the God Machine, ascending himself into Godhood, and causing the great catastrophe.
Lothier is now a God, but due to all the trouble he cause Garnecia, his worship is strictly forbidden. It has been 100 years since he threw himself on the alter and caused the great catastrophe, but it is said that his Divine Trial to retain his Godhood is still ongoing, and thus the distracted Gods have abandoned Garnecia.
*None of this is known with absolute certainty. At the time it was believed that Andrea died in battle, but the profit Raffa told this version of events in his 7th Prophesies and Revelations.