Monmouth Castle was built by William Fitz Osbern shortly after the Norman invasion. He was one of the key supporters of William the Conqueror and played a key role in convincing the Norman barons to invade England. As a reward, the king granted him the Earldom of Hereford, which included extensive lands in the south-west region of the Midlands, making FitzOsbern able to extend Norman control to Wales as well. Timber – earth castle was erected in the years 1066-1069 to dominate the outlet of the river Monnow to the river Wye. These two key waterways were important trade and communication routes that facilitated traffic throughout the region and required strong castles to secure them.
Monmouth Castle was briefly taken over by Richard Marshall, Earl of Pembroke during his rebellion in 1233. Perhaps this attack meant that the then owner, John of Monmouth, built a large, round tower-keep around 1236. In 1256, the castle became a royal property, when it was acquired by prince Edward, later king Edward I. He held it until Simon de Montfort won it in 1264, during his rebellion against Henry III. The king, whom Montfort captured at the Battle of Lewes, was briefly detained in Monmouth as a prisoner. The rebellion was finally suppressed the following year, and the castle returned to the Crown. Henry III then granted the castle to his younger son, Edmund Crouchback, as part of the land he was given when he became Earl of Lancaster in 1267. Edmund considerably expanded the castle, including the building of the great hall.
After Edmund’s death in 1296, the castle and Lancaster Earldom was handed over to his son, Thomas. During his rule, the town walls were modernized to stone, and the king gave him the right to collect fees on the newly created bridge over Monnow. Thomas rebelled against Edward II and was executed in 1322, after which the castle in Monmouth was handed over to his brother Henry. He died in 1345 and the castle was inherited by his son, Henry of Grosmont, prince of Lancaster, who rebuilt the stronghold. In the second half of the fourteenth century, the castle quite often changed owners, and eventually after the coronation of Henry IV again become a royal property.
At the beginning of the 15th century, Owain Glyndŵr’s Welsh rebellion broke out. The castle did not suffer at that time, although a skirmish took place in the suburbs of the town. After suppressing the uprising, the castle was still garrisoned. In the sixteenth century began to fall into ruin, however, some fragments were still maintained and served for the deliberations of the assize courts.
In the 17th century during the English Civil War, the strategic location of Monmouth meant that the castle was garrisoned by a royalists. They kept it until September 1644, when it was taken over by the forces of Parliament. Regained to the king by Lord Charles Somerset in November 1644, it remained again in the hands of the royalists until October 1645, when it was under siege by a Parliamentary army under the command of Colonel Edward Massey, Governor of Gloucester. It was seriously damaged then, because the Parliamentarians tried to undermine its fortifications. After the war, in 1647, on the orders of Oliver Cromwell, a cylindrical keep was demolished to prevent the castle from being used again in military operations.
The original castle from the 11th century was a timber – earth circuit of the walls (ringwork). Fortifications were oval in the plan and consisted of earth ramparts crowned with a timber palisade and, additionally, a moat on the eastern and southern sides. The north and west sides were protected by a steep, natural escarpment falling into the Monnow River. The town with the monastery was located south of the castle.
Inside the oval fortifications there was probably a timber keep, which around 1150 was rebuilt into a stone, rectangular tower. The entrance to it was originally on the level of the first floor and led to a large hall and the chamber of the constable of the castle. A spiral staircase led to the basement-pantry on the ground floor level. The entrance on the level of the ground floor was pierced only at the end of the 13th century, when the building of the grand hall had already been built. Large windows with tracery were added in the fourteenth century. Around 1230, a large cylindrical tower was erected on the north side, which perhaps took over the functions of the earlier keep. It probably had an appearance similar to the preserved keep in Skenfrith Castle. In the second half of the thirteenth century, in the close vicinity of the old building and a cylindrical keep, a rectangular building of the great hall was erected. It was a single-storey building, warmed by a fireplace. Around 1440, the entrance to the castle from the south-east side was reinforced with two flanking towers.
Only fragments of the castle have survived to this day, including the ruins of the great hall building, the ruins of the 13th century keep and part of the defensive walls. The castle now houses a military exhibition at the Monmouthshire Royal Engineers Museum, who from the 19th century has occupied one of the buildings erected in the medieval stronghold.
Kenyon J., The medieval castles of Wales, Cardiff 2010.
Website castlesfortsbattles.co.uk, Monmouth castle.