While the Stormcrown brothers had directed their attention to the invasion and rebellions in the Vale of Arryn, civil war broke out amidst the red dunes of Dorne. During the long reign of Jon Stormcrown, the likes of House Dayne of Starfall had risen to great favor and prominence at his court. That that favor was matched by apathy towards the biddable and meek House Martell of Sunspear proved drastically influential within Dornish politics, and during the long decades had eroded their standing in the favor of not only the Daynes but families like the Fowlers and Yronwoods. The balance of power proved an embittering flavor to all parties involved, and rivalries carried on between fathers extended into open enmity between their sons and grandsons.
And yet it was in Essos not Dorne that the initial strokes of the conflict began, for the actions of Braavos in regards to the Vale of Arryn had attracted the attention of the Free City of Pentos, whose magisters had long since desired to throw off Braavosi shackles. Others in Pentos desired to claim the whole of Old Andalos, and friendships with families in the Vale in league with House Stormcrown communicated quiet approval and support for such initiatives. This in turn attracted the attention of the Martells of the Rhoyne, who though distanced from their Dornish family had long since desired to recover the whole of Old Rhoyne, of which part had long been controlled by the slave-friendly Pentoshi. They desired not that Pentos grow more powerful and independent of Braavos, and thus made their own plans for war.
Thus, Pentoshi involvement against Braavos was stifled when a small Rhoynish army set siege to a client city in their disputed borderlands. This army was followed by several others, all commanded by ex-Dornishmen of Greenblood or Saltish extract. It was an affair that greatly displeased the royal court of Harrenhal, for a dagger thrust by Pentos into the back of Braavos had been reckoned to cut short the war.
In Dorne proper, it was levied against the Martells as proof of disloyalty. And for a region so nearing the brink of conflict for many years, it proved enough to tip all over. Lord Daemon of Sunspear, who was the Lady Arianne's grandson demanded the Daynes present themselves at Sunspear and make an apology. It was refused. A missive was sent to Harrenhal by Lord Daemon, requesting the intervention of House Stormcrown. It was ignored by the Queen Regent Minisa Arryn, whose displeasure regarding the entirety of the conflict in the Vale saw her respond with accusations to Lord Daemon, and demanding that he present himself to Harrenhal to explain the actions of his relatives.
Daemon reluctantly agreed, and made plans to travel first to House Jordayne, before setting across the Dornish Sea to the Stormlands. Turbulent storms prevented that plan, and as a result Daemon was forced to instead travel overland through House Fowler's lands (who were marked to be more loyal to the Martells than the Wyls and Yronwoods). The march passed him through friendly lands belonging to House Vaith, then less uncertain ones of House Uller. The march through Uller lands proved a fatal ones, as hostile temperatures and weather swallowed his convoy whole, never to be seen again.
Almost immediately, a wave of accusations began. House Uller were recognized partisans of House Dayne (though sharing Martell ties though Ellaria Sand, paramour of Prince Oberyn), and were consequently accused of seditious assassination by both the Gargalens and Santagars. To that the Daynes stood against, as did the Blackmonts and Qorgyles. The Martells, backed by the Allyrions, Gargalens and Santagars agreed with this accusation, and again demanded that both the Daynes and Ullers send hostages until the truth could be determined. Refusal was recieved once again, and a bid by the Baratheons of Storm's End to mediate (as cousins to both Daynes and Martells) merited them a stinging insult by not only the Martells but also the Yronwoods. To that end, House Dayne accused House Yronwood of murdered Lord Daemon, an accusation that required Ser Artos Dayne (brother to Lord Beron Dayne, current Sword of the Morning and wedded by marriage to a Yronwood noblewoman) to cut down his wife's nephew in an issued challenge.
King Brynden's son and heir Jon Stormcrown (named for both his grandfathers) was dispatched south by his father to investigate found no wrongdoing by either Daynes or Ullers. A failed assassination attempt on his person only exacerbated matters, and he proved unable to resolved decades worth of accusations and tensions. He promptly withdrew from Dorne following a heated spat with the Martells of Sunspear, cleaning his hands of the whole affair. His retreat proved the final blow on the floodgates of violence, and within days of his setting foot again in the Stormlands all of Dorne was thrust into civil war.
Grudges years or decades unresolved between various families came to bloody conclusions, as all the while House Dayne made to march on both Martell and Yronwood loyalists. The conflict would last roughly fifteen months before House Stormcrown was able to remove their attention from the Vale of Arryn and return southwards, by which point half the Dornish houses had either been beaten into the ground by a coalition of House Baratheon and House Dayne or had switched sides to avoid that fate. The Martells had by then fled first to the Stepstones where their cousins ruled, and then again to the Rhoyne where Trystane Martell's heirs had forced a victorious peace on Pentos, leaving Beron Dayne as master of Sunspear and the Stepstones both.
By royal writ, the following declarations were enacted:
- House Dayne would return both Sunspear and the Stepstones to House Martell, trading brides to cement peace.
- House Wyl and Yronwood, who had insulted both Baratheon and Stormcrown were punished severely with loss of lands to their neighbors.
- House Martell would issue apologies to House Uller, who received lands from House Vaith and other Martell loyalists.
- Rule over the whole of Dorne was to be stripped from House Martell of Sunspear, and passed over House Dayne as well.
- Instead, House Fowler of Skyreach (who had remained largely neutral) were named the new Lord Paramounts.
These decisions were ill-received by most, but were received nonetheless. Only House Wyl of Wyl struck their banner in defiance against House Stormcrown, a decision which was paid upon with fury and wrath in the months that followed, leveling their great castles and exiling most of their house. Their lands passed into the hands of other Dornish lords as well as Stormlanders, and the example proved an ominous one for a yet troubled Dorne. Distant Rhoyne would take heed quickly, and a year later would sign a treaty of friendship with House Stormcrown, surrendering a firstborn son as hostage as Trystane Martell had once been.