In 195 AL, a long-simmering dynastic crisis exploded into civil war. King Aegon IV Targaryen had legitimised all of his bastards on his deathbed. His noble bastards were called the Great Bastards, the most notable of whom was Daemon Blackfyre, a great warrior and wielder of the Targaryen sword of kings, Blackfyre. After King Daeron II Targaryen assumed the throne in 184 AL, his court adopted a 'Dornish' flavour, due to the influence of his wife, Myriah Martell. Some at court took exception to the change. In addition, popular rumors held that King Aegon IV's sister-wife Naerys had shared her affections with their other brother, Aemon the Dragonknight, leading to the possibility that Daeron II was not the legitimate son of Aegon IV.

After more than a decade of building tension, open warfare erupted. Daemon Blackfyre mustered a sizable army against Daeron and was joined by his half-brother Aegor 'Bittersteel' Rivers, a fellow Great Bastard. Brynden 'Bloodraven' Rivers, another Great Bastard, remained loyal to the King. Heavy fighting erupted over the next year, with the Riverlands particularly afflicted. Finally, at the Battle of Redgrass Field in 196 AL, Bittersteel and Blackfyre led a strong force against a royalist army commanded by Prince Maekar and Lord Hayford, the King's Hand. The fighting was very heavy, with Lord Hayford slain. During the battle Blackfyre came face-to-face with Ser Gwayne Corbray of the Kingsguard, wielder of the Valyrian blade Lady Forlorn. Their duel was said to have lasted nearly an hour before Blackfyre gained the upper hand. However, by this time a second royalist force was approaching from the south led by Prince Baelor. At the same time, Bloodraven and his elite archers, the Raven's Teeth, captured and assumed a position atop the Weeping Ridge, which overlooked the battlefield and allowed them to rain arrows down among Blackfyre and his commanders. Bloodraven personally killed Daemon Blackfyre and his twin sons Aemon and Aegon. The rebels began to rout, but Bittersteel rallied them by leading a charge against the Raven's Teeth, taking out Bloodraven's eye in the process. However, Prince Baelor's Dornish spearmen gained the battlefield and crushed the rebel army against Maekar's shield wall.

Bittersteel was able to recover the sword Blackfyre from the battlefield and escape to the Free Cities, where Blackfyre's other sons had already fled. It is unknown how many men took part in the battle, but it is known that more than ten thousand died in the engagement, earning it the name Redgrass Field. Singers would later immortalize the battle with the song The Hammer and Anvil, referring to Baelor and Maekar's strategy.

In 197 AL, one year after the battle, Dorne formally entered the Seven Kingdoms through a marriage between King Daeron's sister Daenerys and Prince Maron Martell of Sunspear.