House Costayne

House Costayne was a Reach house whose lord held Three Towers. During the Dance of the Dragons, it sided with Rhaenyra Targaryen and joined the campaign against the Greens in the south. Its commitment was shown not only in its declaration but in its forces’ direct attacks on Ormund Hightower’s army and supply line, a campaign that ended with Lord Costayne mortally wounded at the Honeywine.

Identity and Allegiance

When King Aegon II’s position in the Reach began to weaken, Lord Costayne of Three Towers was among the southern lords who declared for Rhaenyra. This placed House Costayne among the growing opposition to Aegon, even as House Hightower and Oldtown remained firmly behind him. The young Lord Tyrell’s regents, meanwhile, chose to keep House Tyrell out of the conflict, leaving the Reach divided rather than united under its nominal ruling house.

House Costayne’s allegiance became active military support. As Ormund Hightower sought to march north from Oldtown, Lord Costayne issued from Three Towers and attacked the Hightower baggage train. The assault threatened the army’s supply route while other Reach forces harried its movement, turning Costayne’s declared loyalty into a concrete contribution to the effort to halt Ormund.

The Campaign Against Ormund Hightower

Ormund’s army faced pressure from several directions. Ser Alan Beesbury and Lord Alan Tarly harassed his march with raids, attacks on scouts, and fires in the camp. Lord Costayne struck the baggage train from Three Towers, while a host led by Thaddeus Rowan was reported advancing toward the Mander. Ormund concluded that he could not continue without support from King’s Landing and asked for dragons.

The Costayne attack formed one part of a coordinated effort to isolate Ormund and obstruct his advance. The combined pressure forced his army into a precarious position before the battle at the Honeywine: Rowan’s force approached from the northeast, while Lord Costayne, the two Alans, and their allies cut off the retreat toward Oldtown.

The Honeywine and Lord Costayne’s Fate

At the Honeywine, the allied forces attacked Ormund’s army from front and rear, and his lines began to crumble. The arrival of Daeron Targaryen on Tessarion reversed the battle. Ormund’s soldiers rallied, while the queen’s forces fled; by the end of the day, Rowan was retreating, Alan Beesbury and Alan Tarly had been captured, and Lord Costayne was dying from a wound inflicted by Bold Jon Roxton with Orphan-Maker.

The battle ended House Costayne’s lord’s participation in the campaign. The account establishes his allegiance, his attack on Ormund’s baggage train, his role in the force that cut off the Hightower retreat, and his mortal wounding in the ensuing defeat. It does not give further details about the house’s subsequent leadership or political course.