During the Dance of the Dragons, Jacaerys Velaryon had made allies out of House Stark and House Arryn, the furious Aegon II Targaryen removed his grandfather Otto Hightower from his position as Hand of the King, and appointed his Lord Commander of the Kingsguard Ser Criston Cole. To prove his worth to his King, Criston decided to burn every castle that had declared for the Blacks, and first set his army on the coastal stronghold of Rook's Rest, with both the Greens army and the Kingsguard, marching North.
The Lord of Rook's Rest saw the approach of the army before they had a chance to pillage, so he sent a raven to Rhaenyra Targaryen, begging for help. For days, he saw his fields and villages burning, locked within his castle, Rook's Rest overtaken by the enemy, with no response for Rhaenyra. However, instead of the Blacks army, she sent her former mother-on-law Rhaenys Targaryen, atop her dragon Meleys. She burned the Green army with joy, as her ancestor Rhaenys Targaryen had done before her at the Field of Fire. However, the Greens had set a trap, and Rhaenys was ambush. Two other rose into the sky to attack Rhaenys and Meleys, first Aemond Targaryen on the oldest and largest of dragons, Vhagar. After, Aegon on the most magnificent of dragons, Sunfyre. However, Rhaenys didn't flee, and instead fought the dragons head on, until there was so much dragonflame in the sky, that it seemed like there was a second sun. When the smoke had settled, Meleys had been torn apart by the other two dragons and Rhaenys was a pill of ash. Aemond and Vhagar were the only ones uninjured and Aegon and Sunfyre were mortally wounded.
This led to Aegon having to have a constant dose of Milk of the poppy in order to survive, which could have been the cause of his madness, or could have just added to the fact that he had the Targaryen madness.
Meanwhile, Rhaenyra was frightened by this defeat, fearing that she had lost one of her best fighters and allies. She sent her youngest sons away to Essos, in order to protect them from the dangers awaiting, but this led to another battle.
In the books
Ser Criston Cole, the Lord Commander of the Kingsguard and the new Hand to King Aegon II Targaryen, devised a more aggressive strategy than his predecessor as Hand, Ser Otto Hightower. Criston's force of greens sacked Duskendale and planned a trap for the blacks at Rook's Rest.
Lord Staunton closed the gates of Rook's Rest, but was unable to prevent Criston from burning his fields or killing hissmallfolk and livestock. He asked for assistance from Queen Rhaenyra Targaryen by sending a raven toDragonstone.
Nine days later, Rhaenys Targaryen, the Queen Who Never Was, and her dragon, Meleys, the Red Queen, arrived above Rook's Rest to aid Lord Staunton. However, Criston was prepared and had his archers and scorpions fire at Meleys. The dragon was largely unharmed by these attacks, and she responded by burning Criston's soldiers with dragonfire.
Meleys was then attacked by King Aegon II Targaryen atop Sunfyre and Prince Aemond Targaryen atop Vhagar. The aerial combat between the two dragons of the greens and the one dragon of the blacks saw the deaths of Rhaenys and Meleys. However, Aegon suffered severe burns, while his dragon Sunfyre was rendered flightless from the fight with Meleys.
After the deaths of Rhaenys and Meleys, Aemond, Criston, and the surviving greens took Rook's Rest and killed Lord Staunton and his garrison of one hundred soldiers.
The loss of both Rhaenys Targaryen and her dragon, Meleys, was a severe blow to the blacks. Rhaenys's husband, the Sea Snake Corlys Velaryon, was enraged and blamed her death on Queen Rhaenyra Targaryen, stating that if the queen or her sons had gone with their dragons, his wife might be alive. The heads of Lord Staunton and Meleys were taken to King's Landing.
Ser Criston Cole lost 800 soldiers to Meleys's dragonfire. King Aegon II Targaryen was incapacitated by his burns for a year; Prince Aemond Targaryen became regent while his brother recovered. Aegon's injured dragon, Sunfyre, was left behind and ate carcasses and livestock. Lord Walys Mooton successfully recaptured Rook's Rest for the blacks, then was slain in a failed attempt to kill Sunfyre.