Jon Snow’s voice whispers a phrase involving a “Great War” in the recently-released teaser for Game of Thrones‘ seventh season. But what exactly is he referring to? It takes a book fan to know. George RR Martin’s novels go into great detail about the history of Westeros, including the story of the Long Night. Legend says that this was generation-long period of winter and darkness which took place more than 8,000 years before the events of Game of Thrones, during the time of the First Men of Westeros. As thousands suffered an extreme winter, the White Walkers descended from the farthest north — killing all in their path and raising an army of the dead. A mystical figure known as The Last Hero sought out the Children of the Forest, who united with the First Men to rally against the White Walkers in the War for the Dawn.
A great hero named Azor Ahai helped to win the war with Lightbringer, a sword made out of living fire. Lightbringer was created when Azor Ahai plunged a sword into the living heart of this wife Nissa Nissa, imbuing the steel with her soul. At the end of the war the White Walkers were driven back north and Bran the Builder — founder of House Stark — raised a great Wall of ice, gravel and magic to prevent them from returning Bran was declared the first King in the North, and the Night’s Watch was founded to defend the Wall. But it has been prophesied that the Walkers will return, and Azor Ahai will be reborn to lead a new war.
