Religious event
The followers of the God of Death and Corruption aren't many, and his name is usually never mentioned out loud. Any killer or deviant that seeks to bring death to another calls this God their patron. This is the date that the cult began.
The Cult of Ravens, devoted to Krist, God of Death and Corruption, was created right after the first zombie attack in Garon'd. Before this Krist just had a small following of deranged killers and psychopaths, but in the aftermath of the risen dead, a small cult started. They preached destruction to all unnatural life, and the people wanted to hear it. From there on out where ever undead were spotted, the Cult was there eradicating them.