The Blue Dragon Revolt

While Queen Rhaenyra I Targaryen and the Blacks had won the The Dance of the Dragons, there were still those from the Greens that hated her rule and sought to do anything to bring about her end. House Hightower was chief among them and quietly plotted for several years before bringing bloodshed back to Westeros, producing a man who was claimed to be Prince Daeron the Daring, and his son Aemond. The ensuing conflict was named The Blue Dragon Revolt, for the alleged Daeron the Daring had taken for his sigil a blue Targaryen dragon in memory of Tessarion, the Blue Queen.

Prelude
At the close of the one-hundred forty fourth year since the conquest, House Targaryen has reached its weakest point. The Dragons are gone, dead in their entirety as the last of several pathetic hatchlings succumbs to illness, Sheepstealer is slain in the mountains the year prior, and both Morning and Silverwing were lost in the Witch's War and the Last Dance respectively. But the wounds of the Dance remained open, some still bleeding from the rule of King Aegon II’s mother, Rhaenyra the Black Queen. Most lords have moved past it, and looked to the future, but not all.

On the eve of the new year, Lord Hightower unveils a secret, and plunges the realm into war. At his side, crowned by the High Septon himself, is the long thought dead Daeron Targaryen, thought slain at Second Tumbleton. He is styled Daeron I Targaryen, rightful king of Westeros, the Blue Dragon. Wed in secret to a lady of the Hightower sixteen years ago, the thought dead dragon had apparently lived in exile across the water, waiting for his time to strike.

At the rebel king’s side was his son, Aemond, a boy of sixteen and a knight already, and the fearsome mercenary Tessario the Tiger. This plan had been long waiting, according to those who swore themselves to him and this had been Hightower’s plan all along. In later years, maesters would dispute this, as they would dispute the truth of the supposed rebel king’s identity, the parentage of his son, and nearly every facet of his rebellion.

But in that moment, many a lord who had felt themselves slighted found no reason to question what was presented to them. Those Greens that declared for the rebel were now the Blues, and they drew up new banners, the three headed dragon of House Targaryen dyed cobalt in memory of Daeron’s mount, Tessarion the Blue Queen.

The Uprising Begins
To the disappointment of those who did declare for the Blues, they would find few rallying to their cause. Neither Lannister nor Baratheon dared raise their banners again, nor any other Lord Paramount and in the end their ranks were scattered in small pockets across the continent. Most were set upon by their lieges before they could march to consolidate their forces. Hightower themselves even found their forces bloodied by a defiant House Costayne, though they would manage to defeat their rebellious vassals and move along up the Roseroad, while House Tyrell once again sat out the conflict against the wishes of their Lord, still under a regency deep into his eighteenth year.

The Wrath of the Trout
The forces of Lefford, Tarbeck, and Crakehall managed to unite with the forces of Hightower and Vance in the Riverlands, but bar that, no more aid came. The rebel king remained fully confident in his rebellion nonetheless. Within the Riverlands, the rebel forces won several victories against smaller hosts meant to rise against them, as Lord Vance rode hard and fast to stop any of the lords of the Trident from consolidating their forces. The height of the Blue's fortunes came with the great victory against the forces of Ser Oscar Tully, whose ranks broke when a stray arrow caught one-third of the legendary ‘Lads’ in the throat. However, retribution for this victory was swift.

Lord Kermit, in a black rage at his brother’s death, marched with Benjicot Blackwood at his side, mustering a sizable host which set upon the rebels and battered them in the field at Atranta. Forced back, the Blues retreated to none other than the ruins of Tumbleton.

The Third Battle of Tumbleton
Haunted by his cowardice in the Gullet as a boy, and longing for the recognition and praise his brother received for his sacrifice in The Last Dance, Aegon II sought out the Blue King in the field. His desire to find his enemy was not just driven on by this guilt, but also by the death of three of his loyal Kingsguard, Ser Lyonel Bentley, Ser Raynard Ruskyn, and Ser Marston Waters - the latter of whom fell at Daeron's own hand. Many of the major lords of the Crownlands raised their banners to join King Aegon II in his fight against the Blue Dragon. Many of the major lords joined the army, including Lords Darklyn, Velaryon, Celtigar, Staunton, and Rosby. They marched with King Aegon to Tumbleton and fought with him in the battle as Lord Kermit and Benjicot rode south their their men from the Trident.

While never shameful at arms, Aegon never showed any gift for them either. When he found his opponent, a man seemingly hardened by years in exile, the fight was intense, but ultimately one sided. No account ever diminished the King’s bravery, but nor did they praise his skill. Cut down by Daeron, the king was slain by his opponent and the pretender took up Blackfyre for but a moment. Seconds later Daeron was cut down by a hail of arrows from Lord Benjicot and his men, his forces encircled and gutted. The rebellion ended on that day, and with it, any remaining dreams that the line of Viserys and Alicent would ever claim any throne.

Aftermath
The men of the Blues that survived were rounded up, the Lords among them, and the pretender’s son were taken to King’s Landing, while the men were sent home. Most lords pleaded mercy, and found it at the wall, in exchange for their sons being taken as hostages. Those that did not met the sword, and more amenable relatives were negotiated with for peace. This was the case for all but two.

Lord Hightower was taken prisoner and escort to King's Landing, and for their continued defiance so too was the rest of his family in a series of high profile trials in the capital that came to be known as the Hightower Trials. The proud seat of Oldtown being bestowed upon the loyal House Costayne, and the ancient line of the Hightower’s were no more.

"Prince" Aemond, the pretender’s son, met a much crueler fate. Tortured until he declared that both he and his father were in fact pretenders, and nothing more than mercenaries born in Lys. Only then was the boy of ten and six given the mercy of death, but as he was supposedly ignoble, and not yet a knight, he found it from a noose rather than a blade. To this day, the legitimacy of this ‘confession’ is questioned by many, as those who saw the boy before his death attested that one in his condition might’ve said anything in order to be given mercy.

The small war spawned many a song and tale, a shocking amount for a conflict so small in fact. The Dragon’s Despair, a ballad based on the widely reported breakdown that Daeron the Pretender suffered upon entering Tumbleton became quite popular despite efforts to suppress it. Some sympathetic to the Blues cite the events described in the song, which is corroborated by several first hand reports, as proof Daeron was no liar, and that being of the site of his near death caused him great pain. Others more critical speculate that the supposed Targaryen was fearful his lie would be discovered so close to the grave of the true Daeron the Daring.

In the end, the war became little more than a footnote, largely remembered only for being the death of King Aegon, and being the beginning of the regency for the young Queen Baela Targaryen, who was but three at the time.