Great Council of 305 AC

The Great Council of 305 AC of the Seven Kingdoms saw the election of King Brandon I of House Stark and the secession of the North from the Seven Kingdoms under Queen Sansa Stark. The council was originally convened to address the fate of Tyrion Lannister and Jon Snow, but also elected a new king who would pass judgment against the two. It was the first formal election of a monarch in the history of the Seven Kingdoms, though the choice of succession had in the past been influenced through other Great Councils.

Election of Bran Stark
"There's nothing in the world more powerful than a good story, nothing can stop it, no enemy can defeat it, and who has a better story than Bran the Broken?"

- Tyrion Lannister to the assembled lords at his trial

Originally a trial intended to determine the fate of Tyrion Lannister and Jon Snow following their roles in the death of Daenerys Targaryen in the aftermath of the Battle of King's Landing, Tyrion insisted that a king (or queen) would be needed for the trial. Though the assembled lords and ladies were uncertain of whom to choose and only Lord Edmure Tully put forth a nomination (nominating himself), Tyrion ultimately suggested Bran Stark, who was subsequently accepted as king by all present, except his sister Sansa Stark, who demanded, and was granted, the independence of the North. Tyrion declares an elective monarchy, stating that a Great Council will be held at the Dragonpit every time a king dies.

Secession of the North
"I love you, little brother, I always will. You'll be a good king. But tens of thousands of northmen fell in the Great War defending all of Westeros, and those who survived have seen too much and fought too hard ever to kneel again. The North will remain an independent kingdom, as it was for thousands of years."

- Sansa Stark to Brandon

The notion of independence for the Kingdom of the North had been a prevailing issue for many years, ever since Joffrey Baratheon beheaded Lord Eddard Stark at the foot of the Great Sept of Baelor. Robb Stark, Eddard's eldest son, was forced to raise his banners in rebellion against Joffrey, but the northerners did not wish to support either Stannis or Renly, the late King Robert Baratheon's brothers, against Joffrey's claim. Instead, they crowned him King in the North.

Robb Stark's war for independence would be successful until he broke his betrothal with Roslin Frey to marry Talisa Maegyr, a Volantene noblewoman whom he had met on campaign. As a result, Lord Walder Frey orchestrated the Red Wedding with Tywin Lannister, a successful massacre of the northmen that dined within his halls for Edmure Tully's wedding to Roslin. During this murder, both Robb and his mother Catelyn Tully were killed, beginning the Stark-Lannister blood feud. After the assassination, Roose Bolton would be named as Lord Paramount of the North and Lord of Winterfell, replacing the Starks and earning the distrust of many northern houses, whose banners had been pledged to the Stark cause.

Roose would later be murdered in a conspiracy by his legitimised bastard son, Ramsay Bolton, who would continue to rule the north through fear tactics and brutal violence. Eventually, there was hope for the North when Jon Snow marched south from Castle Black to take back Winterfell with his sister, Sansa. Despite this, he only managed to obtain the support of House Mormont as well as other minor houses, as larger houses were unwilling to fight alongside the Free Folk.

With the threat of the Army of the Dead looming, Jon Snow, crowned King in the North by his newly pledged vassals, would be forced to seek an alliance with Daenerys Targaryen, with whom he quickly fell in love. From Dragonstone, he would bring her home to Winterfell back to the northerners, who still maintained a residual hatred for House Targaryen after the brutal torture and murder of Brandon Stark and Rickard Stark by Aerys II Targaryen twenty years prior. This hatred was even more amplified when, after the Great War, the northmen suffered great casualties, and were still forced to go to war with the south. Sansa Stark was most dissatisfied with this.

Eventually, after the Battle of King's Landing and the Great Council, Brandon Stark's selection as King of the Andals and the First Men would finally allow Sansa to achieve legal independence for the North as a recognised polity, free from what was now the Six Kingdoms.