The first castle on the site is believed to be one of the very few which were built under the Saxons before the Norman conquest. This structure was likely raised in 1048, possibly by Osbern Pentecost, on the site of an earlier fortification. It was a motte and bailey castle overlooking the Dulas Brook. In 1052 the original castle was destroyed, either on the orders of Earl Godwin or by the Welsh in a raid.
In the jurisdiction of the castle of Ewyas Harold, Roger holds of Henry three churches and a priest and 32 acres (130,000 m2) of land and they render two sesters of honey. In the castle he has two messuages.
The castle fell into partial decay until the early 15th century. It was then in the possession of William Beauchamp, Lord Abergavenny, who refortified it in the face of the threat from Owain Glyndŵr. There is no record of it being attacked at this time. Owain and his various forces focused their attention on strategies and opportunities elsewhere.
The castle again fell into ruin by 1645, and today only earthworks remain on the edge of the village to mark where it once stood.
- Ann Williams; Geoffrey Haward Martin (2003). Domesday Book (Penguin Classic): A Complete Translation. Penguin Classics. p. 511. ISBN 978-0-14-143994-5.
- Ewyas Harold Castle at "The Gatehouse" accessed July 2009
- Plantagenet Somerset Fry (1980). The David & Charles book of castles. David & Charles Publishers. ISBN 0-7153-7976-3.
- Bannister, Arthur Thomas, The history of Ewias Harold, its castle, priory, and church (Hereford 1902)