House Canmore, their coat of arms a black spider settling on a web between two weirwood trees, was founded during the reign of Aegon V by Rhodri Map Merfyn Map Merfyn Canmore whose hair was a mix of gold and dark ebony, with a strong jaw, sharp nose, and grey eyes, it was only in their face where the common feature of the family became apparent, they are known as the Breeding Horses of True North and of Westeros as they were well known to be a virile and fecund house next to that of the now extinct House Gardener of the Reach with many branches springing out of the main line which rules the Kingdom of Hengledd..." - The Lineages and Histories of the Great Houses of Westeros and the True North by Grandmaester Malleon.
Gisla Fer Anarawd, was married to Styr Map Sigr, whose lineage boasts of being of the original Magnars of the Vale of the Thenns before they were supplanted by the Canmores, their marriage was for Anarawd to please the Tanists and also to prevent breaking the laws of the gods concerning marriages so close to the bloodline, as one of his relatives had proposed to him, particularly Merfyn Map Gwain Map Merfyn, a fact which was practiced by House Targaryen of the Iron Throne, albeit very extremely in the latter's case. Even the rest of his daughters themselves married outside of the Canmore line, Anarawd's eldest, Rhiannon Fer Anarawd, was sent to Skagos where she was married into House Magnar of King's House, whereas the youngest, Morgan Fer Anarawd, married into the Gallowglass Clan Karstark. Gisla was a safe choice as an heir by Anarawd, she was practically the middle child, if he chose Rhiannon the Tanists would accuse him that he is furthering the interests of the South, the same could be said of Morgan as the Gallowglass Clan Karstark boasts of their connection to House Stark, and so before he died of illness he declared that Gisla and her husband shall inherit his throne much to the shock and consternation of both the Tanists and Royalists, as some chieftains preferred his nephew, Brandon Map Gwain Map Rhodri and he himself had expected to be chosen as heir by Anarawd.
The rule of the King and Queen Beyond the Wall lasted only for five years, but it was a prosperous five year reign as they had managed to settle the giants at one of the open plains near the Cooleys and had created more farmsteads and hamlets to pockets of land that began to grow warmer due to the absence of the Others blasting them with the cold, but to the Tanists and some of their relatives it was a reign which was marked with the King and Queen not allowing clans to create settlements on the Shivering sea, and the fact that their predecessor had basically become a lackey to the Kings in the South and had tried to enforce what they think of as weak kneeler values to their strong True Northmen culture, indeed Rhodri Map Merfyn Map Merfyn the first Canmore was considered to be a strong unifying figure to the kingdom but still the great dead king had upended centuries of customs and cultures which existed before he had established his rule, it was like heat trapped within a container which will burst on the fifth year in the reign of Gisla and Styr.
The Tanist Siege of the Cooleys was an unexpected event in the Kingdom of the True North, maesters and druids had agreed that the attack was led by both Brandon Map Gwain Map Rhodri and Merfyn Map Gwain Map Merfyn, Brandon was supposed to be chosen as heir by both the Tanists and Royalists he felt that he was cheated of his claim to the weirwood throne, Merfyn was insulted by Anarawd and Gisla when he proposed to have one of his sons marry her in the Targaryen tradition and was rejected with Gisla threatening to cut off the manhood of Merfyn's son if he tries to steal her. The attack started when the Tanistry was regularly held and both King and Queen were in attendance, the giants were unexpectedly to have attended the proceedings as it seems they have begun to prosper once more and had wished for the Canmores to see the fruits of their gifts to them, showing off mammoth cheese and milkwine which was accepted by both Styr and Gisla and had congratulated the giants for their good fortune, there must have been a hesitance in both Merfyn and Brandon's actions as they were the last to push themselves through the crowd of conspirators who were in position to kill Gisla, her husband, and her two boys, but still they went through, the signal came when one of Merfyn's men struck at Ser Bonifer, it was there where both Brandon and Merfyn unsheathe their swords and struck the King and Queen, young prince Anarawd was beheaded by Brandon.
Caradog survived if not for Ser Daemon of Clan Hasty who quickly took him out of Anarawd's Great Hall and had quickly led the now young king towards the upper Great Hall and had the gates and doors leading to it blocked, he had a Gallowglass with the powers of skinchanging to send a message to a nearby army to march towards the Cooleys and the King's Gallowglasses to defend the upper Great Hall to the death if need be, it was a grueling whole day siege which was broken at the dawn of the second day when the giants have finally broken the conspirators who fled the Cooleys when their attempts to climb over one of the walls of the upper Great Hall was stopped by the giants when they took to climbing to the hills of the upper Great Hall. To the Tanists who participated in the siege it was a call to return to the Yr Er Ess Rok the 'Noble Free age', to Brandon and Merfyn as well as their Royalist supporters it was a comeuppance to the line of Anarawd Map Rhodri Canmore who had insulted them time and time again with his kneeler appeasements, what they did not expect was King Caradog Map Gisla's vengeance.