Claim: Einion ap Collwyn persuaded Robert FitzHamon (known as lord of the honour of Gloucester and the first Norman feudal baron of Gloucester) and twelve other knights, to bring a army to the aid of Iestyn, which led to the fall of the kingdom of South Wales.
Evidence: Einion visited his English friends at London. He persuaded Robert FitzHamon, historically lord of the honour of Gloucester, and twelve other knights, to bring a great army to the aid of Iestyn. Rhys was slain by them in a terrible battle near the boundaries of Brycheiniog, at Hirwaun Gwrgan. With Rhys fell the kingdom of South Wales. Robert Fitzhamon (died March 1107), or Robert FitzHamon (literally, 'Robert, son of Hamon'), Seigneur de Creully in the Calvados region and Torigny in the Manche region of Normandy, was the first Norman feudal baron of Gloucester and the Norman conqueror of Glamorgan, southern Wales.