Dinieithon Castle was a motte-and-bailey fortification built circa-1090 by Ralph de Mortimer as part of his efforts to subjugate Central Wales. The fortification had a short lifespan as it was completely destroyed during a Welsh uprising in the 1130s. It may have been rebuilt a few decades later but, if so, it only remained in use for a short period before being replaced by Cefnllys Castle.
Dinieithon Castle was built circa-1090 by Ralph de Mortimer, a Marcher Lord intent on expanding his influence deep into Wales. The castle's purpose was to control the River Ithon, a key waterway that linked central Wales with the River Wye, itself an important communications artery with England.
The castle was an earth and timber motte-and-bailey fortification. It was built upon a steep scarp to the east of the River Ithon whilst a natural spring provided an additional defence to the south as well as providing potable water for the castle. The D-shaped motte occupied the summit of the rise and would have been topped with a timber palisade. A bailey probably extended to the west occupying the ground between the motte and the river.
Dinieithon Castle was destroyed by Madog ab Idnerth in the 1130s. It may have been rebuilt circa-1165 by Madog's son, Cadwallon, but if this was the case it had a short lifespan as the last recorded reference to the site dates from 1179. In the decades that followed it was replaced by Cefnllys Castle, located one mile to the south, which occupied a much stronger defensive position.
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Dinieithon Castle survives as overgrown earthworks. The motte is on private land but can be seen (from a distance) from the right of way that connects to the road to the river.
Dinieithon Castle. The (now overgrown) motte occupied the high ground. A bailey extended west (right) towards the river.
River Ithon. The river provided a line of communication between England (via the River Wye) and central Wales.