- "There's only one war that matters: the Great War, and it is here."
- ―Jon Snow
The Great War is a conflict that began following the de facto conclusion of the War of the Five Kings. It is the ultimate culmination of the long-simmering Conflict Beyond the Wall. The opening stages of the Great War are a war of attrition between the Night King, his legions of White Walkers and their undead thralls (collectively, the "Army of the Dead"), and several of the the living peoples of Westeros – the Night's Watch, the North, the Free Folk, and the Knights of the Vale – under the leadership of Jon Snow, the King in the North. Although expected to threaten all of Westeros, the Great War at its beginning is centered on the North, as the southern kingdoms are more preoccupied with the aftermath of the War of the Five Kings and Daenerys Targaryen's invasion of Westeros, another long-awaited event which began around the same time the North started preparing for the Great War.
- "Jeor Mormont and Jon Snow both understood that the real war isn't between a few squabbling houses. It's between the living and the dead. And make no mistake my lady, the dead are coming."
- ―Davos Seaworth
- "If we don't put aside our enmities and band together we will die. And then it doesn't matter whose skeleton sits on the Iron Throne."
- ―Davos Seaworth
After being crowned King in the North Jon Snow begins formulating a plan to defend the realm from the army of the dead. He decrees that all children, regardless of gender must begin training to fight.
Thousands of miles away in Oldtown, Samwell Tarly, another veteran of the Conflict Beyond the Wall, scours the Citadel's library for information that can be used to defeat the White Walkers. His best lead is the discovery that enormous amounts of Dragonglass, one of only two substances lethal to White Walkers, can be found on Dragonstone.
In the books
In the A Song of Ice and Fire novels, the Great War, while heavily referenced as an impending event, has not yet begun in earnest. The conflict between the Night's Watch and the Free Folk is still in progress, and Stannis Baratheon still lives, and is currently marching on Winterfell in an attempt to retake the North from House Bolton.