Rhys ap Tewdwr's Nephew. The Gormghael Chronicles, #3

In 1090, the Welsh border is a place of shifting loyalties and encroaching Norman iron. Enter Eidio ap Sitric, a shrewd Hiberno-Norse mercenary exiled from the stone sophisticated courts of Dublin. Rebranded on the advice of his royal uncle Rhys as Eidio Wyllt-the Wild One-he is granted the isolated mountain lordship of Llywel. To the suspicious Welsh clans, he is a terrifying foreigner; to the invading Marcher lord Bernard de Neufmarché, he is just another obstacle to be crushed.
Weaponizing his advanced engineering, and flawless diplomatic fluency, he anchors his vanguard into the red sandstone. When the fragile peace shatters, Eidio is forced into a desperate, transactional alliance with a powerful Welsh chieftain, sealing his fate through marriage to the young princess Elinor. Spanning centuries from the brutal 1105 crucible to the devastating demographic bottlenecks of the Black Death and the trenches of the Great War, this epic narrative traces a resilient, extraordinary bloodline.
Perfect for fans of Bernard Cornwell and historical family sagas, this book explores how an agonizing personal tragedy forged an unassailable dynastic anchor that survived the collapse of empires to live on in modern veins.