1. The Three Castles - Grosmont, Skenfrith and White Castle - were held by a single owner from 1138 until 1902 when they were sold off individually by the Beaufort estate. At present ownership is still split; White Castle and Grosmont are owned by the State whilst Skenfrith is owned by the National Trust.
Grosmont Castle, along with Skenfrith and White , was built to dominate the border Lordship of the Three Castles. Surviving multiple Welsh rebellions, including one by Owain Glyn Dŵr that was ultimately suppressed by the future Henry V, it was abandoned no later than the early sixteenth century.
HISTORY OF GROSMONT CASTLE
Following the Battle of Hastings, William I (the Conqueror) appointed one of his principal supporters, William FitzOsbern, as Earl of Hereford. After building significant castles at Chepstow and Monmouth, William overran the surrounding Monmouthshire territory including that occupied by Grosmont Castle. It was sometime late in the eleventh century when the first castle was raised at the site; initially built as a earthwork and timber fort.
One of three castles (the others were Skenfrith and White), it was situated in an area such that it could dominate and control the local area whose populace were entirely Welsh; the contrast between the French speaking Normans and the locals could not have been starker. Inevitably rebellions and uprisings against the Norman overlords followed the result of which was ongoing upgrades to Grosmont. In particular the castle was remodelled between 1201-22 when the then owner, Hubert de Burgh, rebuilt in stone to the latest continental design.
Grosmont was attacked by the Welsh in 1405 during the Owain Glyndŵr uprising but, due to a relief force being dispatched from Hereford by the future Henry V, failed to capture the castle. This was the last time the Welsh rose against Grosmont and by the sixteenth century it was in a ruinous condition.