J.K. Rowling officially ended the Harry Potter series in 2007 — but even if her title character's story is over, there are plenty of aspects of the wizarding world left to explore. In addition to her upcoming screenplay for Fantastic Beasts and Where to Find Them, Rowling has taken to her website Pottermore to flesh out the long and storied history of the Quidditch World Cup.
The new story serves as a kind of guide to the sport, chronicling the precise rules of the game. The highlight, by far, is the section on "infamous tournaments," which describes several of the strangest moments in Quidditch World Cup History — including the "Reappearance of the Dark Mark":
Possibly the most infamous World Cup Final of the last few centuries was the Ireland-Bulgaria match of 1994, which took place on Dartmoor, England. During the post-match celebration of Ireland's triumph there was an outbreak of unprecedented violence as supporters of Lord Voldemort attacked fellow wizards and captured and tortured local Muggles. For the first time in fourteen years, the Dark Mark appeared in the sky, which caused widespread alarm and resulted in many injuries among the crowd. [Pottermore]