When first the Targaryens returned to Westeros, some sought to work the instability of their fledgling rule to their advantage. The anti-Targaryen sentiment and efforts were widespread by these rebels throughout the Kingdoms, albeit shortened by the threat of dragons and their riders themselves, and dubbed in the years to come The Year of False Banners.
The Vale[]
With the ascension of King Aegon VI and Queen Daenerys I came peace, for a short time at least. In the Vale life had continued as it always had under the rule of House Arryn and Lord Paramount Robert Arryn. But as many would come to find, the young Lord Robert was a weak lord aided immensely by his closest ally Lord Yohn Royce, until Lord Royce's death in 314 AC.
It didn't take long before the other noble houses of The Vale began to notice how unsuited the young Lord Robert was to ruling and quickly began making plans to rebel against their liege lord. In 315 AC, Taking notes from Tyrion Lannisters escapades through the Vale during the War of the Five King's, the rebel lords of Houses Sunderland, Borrell, Torrent, Templeton and Hardying employed the hill tribes of the vale to attack the bloody gate and the eyrie with promises that they would be rewarded with their own lands after Robert Arryn was dead. The hill tribes did as they were paid to do and sent wave after wave at the bloody gate while Lord Arryn assembled his lord bannermen to him. the first to arrive were the rebel lords who quickly subdued Lord Arryn and sent him through the moon door.
It didn't take long for the other Noble Houses of Westeros to answer when they heard of what happened to the young lord Robert Arryn. Within the Moons turn Houses Stark and Tully were putting down the sieges led by the hill tribes (effectively wiping the tribes out for good), while Houses Corbray and Royce pushed through and attacked the Eyrie only for King Aegon himself flew to the Eyrie on dragonback, the rebel armies quickly laying down their swords at the sight of Rhaegal. After allowing the Corbray's and the Royce's inside the leaders of the rebellion were either sent through the moon door or put to the sword (those who were put to the sword were also fed to King Aegon's dragon). In the aftermath, due to Robert Arryn never siring an heir for house Arryn, the Vale and lordship over the east was given to House Corbray
The Stormlands[]
The final rebellion of The Year of False Banners came from House Baratheon and the Stormlands. Shortly after the defeat of the Vulture King in Dorne, the new Lord Arthur Baratheon (Gendry's eldest son) came to believe that despite everything his father had done to help the Targaryen's reclaim the Iron Throne that the crown had favored the Dornish due to King Aegon's blood ties to the Princess Arianne Martell. Lord Arthur decided that a true king would not favor one kingdom above the others and began plotting his rebellion, finally kicking it off during the waning months of 315 AC.
Unlike Robert's Rebellion some 30+ years before, this Stormlords rebellion wouldn't end with the death of a Targaryen King. While Arthur Baratheon was revered as a great warrior, he was not well loved by the other lords of the seven kingdoms and other than his own bannermen had trouble recruiting any strong noble houses. The first meeting in the field between the Rebel Stormlord and the Targaryen loyalists would be the last as both King Aegon and Queen Daenerys would make use of both their dragons, effectively wiping out Lord Arthur's army.
in the aftermath Lord Arthur was not allowed to claim a trial by combat or to join the Night's Watch as he requested but was instead beheaded by King Aegon himself on the steps of the Red Keep. Storms End would be given over to Lord Alaric Dondarrion until Argella Baratheon, Lord Arthur's daughter who was brought to King's Landing as a hostage, comes of age.
The Riverlands[]
With the rise of the Vulture King in the south, and as other rebellions sprung up throughout the Seven Kingdoms, Black Walder Frey made a bold move against House Tully, his ultimate motive to kill Lord Edmure and destabilize the Riverland's. Through clever use of deception and money, the Lord of House Frey brought three powerful bandit groups to fold, and employed them against the Lord of the Riverland's.
Three years of clever tracking and planning by Houses Tully, Arryn, Stark and Lannister with some support from Kings Landing, were all that was required to root out the bandit groups. Though Black Walder's complicity was never discovered, it was revealed by his son and heir shortly after his death a decade later.
Dorne[]
Rife with skepticism, Dorne contributes their disbelief that Aegon is truly the son of Elia Martell, who had been believed for many years to have met his end as an infant by the hand of Ser Gregor Clegane. Distrusting of the Targaryen's return and further apprehensive of their dragons, many Dornish houses call for independence whilst others remember the Conquest that first saw them annexed.
Amidst both cries for secession and to swear fealty, another Vulture King rose from the Red Mountains to choose rebellion. Caravans flying the banner of the dragon and that of their loyalists were attacked and looted; riots were incited in protest of Dorne's inaction - one of which saw to the utter destruction of the Water Gardens, for its relevance to peace with the Targaryens.
Shortly after the riots were quelled in Dorne, King Aegon VI called a meeting of the lords of Westeros with the attendance of Dorne's Princess Arianne Martell required. The Council of Seven (as it would come to be known in the later years of King Aegon's reign) saw many of the lords pointing the blame at Arianne Martell for her inaction in putting down the Vulture King's rebellion. These sentiments are quickly squashed by King Aegon who would not tolerate his cousin to be slandered.
The Council of Seven lasted well into a week before it was decided. the realms would unite against the growing threats. Houses Tully, Corbray, Stark and Lannister would quell the bandits who had been terrorizing the Riverlands with whatever support King's Landing could spare. While in dealing with the Vulture King it was agreed that Houses Targaryen and Baratheon would attack from the North, House Tyrell from the West and House Martell would attack from the South effectively sealing the Vulture King and his forces in the Red Mountains.
The Plan worked marvelously and with the added advantage of House Targaryen's dragons and the Golden Company, the Vulture King's forces were quickly subdued and the Vulture King was slain by King Aegon himself in single combat.