Caerphilly Castle was a vast medieval fortress built in hostile territory to secure control of the upland region of the cantref of Senghennydd. Its concentric layout represented the very latest in castle design and would be imitated by the later Royal castles built by Edward I to suppress North Wales.



The Romans


The Romans built a fort at Caerphilly around AD 75 as an outlying garrison attached to the Second Augustan Legion (Legio II Augusta) based at nearby Caerleon. The army had been tasked with pacifying the Silures tribe who occupied much of South East Wales. The 5,500 soldiers of the Legion operated from Caerleon but they were augmented by the same number of auxiliary troops, non-Roman citizen soldiers drawn from around the Empire, who were deployed across the wider region. The fort was configured in the normal 'playing card' shape associated with Roman military outposts of the period and enclosed an area of around three acres suggesting it was probably home to an infantry regiment. The defences consisted of an earth rampart riveted with timber beams which were fronted by twin V-shaped ditches. Archaeological finds suggest occupation continued into the mid second century AD.




At the time of the Norman invasion Caerphilly Castle was part of the cantref of Senghennydd, a lordship which occupied a thin strip of land extending northwards from the coast between the Rivers Rhymney and Taff and stretched to the Brecon Beacons. This formed part of the Welsh Kingdom of Morgannwg whose ruler was Caradog ap Gruffudd, an individual who forged a working relationship with the Normans. However, when he died in 1081 the Normans occupied the coastal region and it was probably William I himself who built Cardiff Castle at this time. The reign of William II (1087-1100) saw further Norman expansion in South Wales with the King encouraging Robert Fitzhamon, Baron of Gloucester to expand his territorial holdings in the area. Supported by twelve Knights and their retinues he advanced from Gloucester around 1089, built Newport Castle and then moved west into the Vale of Glamorgan where he established his administrative centre at Cardiff. By the time of his death in 1106, he had advanced as far west as the River Ogmore. Despite his success, he limited his expansion to the coastal region where the flat terrain suited Norman military operations and made resupply relatively easy. Accordingly the upland portion of Senghennydd, including the site of Caerphilly Castle, remained unoccupied by the Normans at this time.


The de Clare Family


The de Clare family acquired the Lordship of Glamorgan in 1217 and became Earls of Gloucester from 1225. The divisions forged during the late eleventh century, where the Glamorgan lowlands were under Norman control whilst the uplands were in the hands of the Welsh, had endured to this time and the de Clares resolved to conqueror the whole area. Periodic warfare followed with Gilbert de Clare (d.1230) and Richard de Clare (d.1262) expelling the Welsh from the uplands immediately to the north of Cardiff. However it was Gilbert de Clare, Seventh Earl of Gloucester who took the initiative to seize the upland portion of Senghennydd from its then owner, Gruffudd ap Rhys. Clare's actions had been authorised by Henry III on the grounds that Rhys had supported Llywelyn ap Gruffudd, Prince of Wales who had exploited the political turbulence of the Second Barons' War to expand the area under his control at the expense of the English. Clare advanced north in 1267 and by April the following year had commenced the construction of Caerphilly Castle within the Rhymney valley.


Caerphilly Castle


The design of Caerphilly Castle was heavily influenced by Kenilworth Castle, a major Warwickshire fortress protected by vast artificial lakes, which had recently defied Royal forces during the Second Barons' War. At Caerphilly a large fortified dam was created to trap the flow of the Nant y Gledyr stream. This created a large artificial lake with the castle occupying a natural gravel spur that was levelled to create a flat platform for the castle. A further island, known as the Western Island, was also fortified. The primary purpose of these water features was defensive - a water-filled moat or lake prevented undermining whilst the effective range of throwing machines and other such artillery was limited to around 300 metres. However, the lake would also have served an economic function and was doubtless used as a large fishpond, an important source of food in the medieval household.


Whilst the outer defences were influenced by earlier fortifications, the castle itself was a significant departure from previous structures. It dispensed with a Keep, the traditional redoubt that was normally the strongest part of such a facility, and instead adopted a concentric design consisting of a double circuit of walls with strongly fortified gatehouses. The outer defences enclosed the entire island with a low wall and was accessed via small gatehouses on the east and west sides. The inner defences formed a broadly rectangular area with a round tower on each corner. A large gatehouse dominated the eastern side of the castle which doubled as the Keep and also included high status accommodation. The west gatehouse had a smaller footprint but was still a substantial defensive structure in its own right. The design of Caerphilly Castle was a significant influence on Edward I who imitated its design in his own Welsh fortresses - such as Beaumaris, Conwy, Caernarforn and Harlech - that were built in the subsequent decades.


A small town was established to serve the needs of the castle. This was located to the south of the castle and interestingly the town was not protected by its own walls, a remarkable situation given this was a fortification built in hostile territory. It is likely the Western Island was used as a redoubt for the populace in times of the trouble.

The Inner Ward and Middle Wards of Caerphilly Castle were built to a concentric design. The Inner Ward East Gatehouse doubled as the Keep.

Llywelyn ap Gruffudd


By the time work started on the castle in April 1268, Henry III and Llywelyn ap Gruffudd had sealed the Treaty of Montgomery (1267) which aimed to bring peace between the two parties. However, the scale of the work at Caerphilly outraged Gruffudd who attacked it early during the construction process. Significant portions of the castle were timber at this early stage and they were burnt bringing the build process to a halt. Henry III attempted to defuse the situation but de Clare simply moved back in and resumed construction. As far as de Clare was concerned, this was the Welsh March where the 'King's Writ' did not apply. Significant resource was diverted to the construction effort and the castle was completed at an breathtaking speed with the bulk of the work having been completed by 1271, just three years after it had started.


Wars of Welsh Independence


In 1272 Edward I became King of England and, whilst he initially maintained the provisions of the Treaty of Montgomery (1267), relations with Llywelyn ap Gruffudd soon broke down. Two Wars of Welsh Independence followed which led to the end of native Welsh rule. Whilst the major actions were north, central and south-west Wales, de Clare made numerous upgrades to Caerphilly Castle during the troubles. The walls of the Inner Ward were heightened and the dam extended to create a new North Lake.


Morgan ap Maredudd


In 1294 Madog ap Llywelyn, a descendant of the deposed Princes of Gwynedd, launched a rebellion against the English rule. He was joined by Morgan ap Maredudd whose father had been deposed by Gilbert de Clare. Morgan attacked and captured Morlais Castle and then advanced on Caerphilly. The castle withstood the attack but the town was burnt. By April 1295 Gilbert de Clare had counter-attacked and was back in control of the region. Despite the success of Caerphilly Castle, the incident seems to have prompted construction of additional defences along the North Dam - the protecting curtain wall was heightened at this time and three towers added to it.

Morgan ap Meedudd successfully seized Morlais Castle but the defences at Caerphilly proved too strong.

After de Clare


Gilbert de Clare died in 1295 and was followed by his son, also called Gilbert. Like his father, he took a prominent role within the Royal court and in 1314 led a portion of the vanguard in Edward II's Scottish campaign to relieve Stirling Castle. However, the English forces were engaged by Robert the Bruce at the Battle of Bannockburn and in the first day of fighting, de Clare's forces were routed. The following day Gilbert was cut down and killed during the main battle. He left no male heir and the castle passed through a succession of custodians whose treatment of the Welsh was seemingly poor and prompted a local rebellion in 1316. This uprising was led by Llywelyn Bren who attacked Caerphilly Castle with a force of 10,000 men. The castle's defences held out but once again the undefended town was burnt to the ground and some unfortunate citizens caught outside the walls of the castle were brutally murdered. The rebellion was brought under control in March 1316 when a Royal army marched into the region.


Hugh le Despenser


Edward II's unpopular favourite, Hugh le Despenser the Younger, acquired the Lordship of Glamorgan (including Caerphilly Castle) through his marriage to Eleanor de Clare. However, in 1326 the King was overthrown by his estranged wife, Queen Isabella, and Roger Mortimer, Earl of March. The King fled into Wales and took refuge at Caerphilly Castle but left before the Queen's forces arrived and was later captured at Llantrisant. Hugh was hanged whilst Edward II was forced to abdicate and taken into custody ultimately ending up in Berkeley Castle where he may have been murdered. Caerphilly Castle continued to resist the Queen's forces and remained besieged until March 1327 when a general pardon was offered to its garrison including Hugh Despenser the Younger's son, also called Hugh.


Later Medieval Period


The castle remained with the Despenser family until 1415 after which it passed through marriage to Richard Beauchamp, Earl of Worcester. As tensions with the Welsh eased, Caerphilly Castle became increasingly irrelevant. Legal courts continued to be held within the castle and the site was used as a prison until the late sixteenth century. However, the defences were neglected and when John Leland visited it in 1538 he described it as ruinous. In 1583 the then owner - Henry Herbet, Earl of Pembroke - authorised stone to be removed for construction of a nearby house. Furthermore the lakes were drained which caused some subsidence to the castle foundations as the islands dried out.


Civil War


The ruined state of the castle meant it played no part in the seventeenth century Civil War. However, following the end of the First Civil War, during which Wales had enthusiastically supported the Royalist cause, Parliament was wary of the structure. Whilst Parliamentary forces didn't refortify it themselves, in 1647 they built a small fort adjacent to the site within the perimeter of the former Roman fort whilst work was ongoing to slight the castle. Some restoration was done in the early twentieth century and in 1950 it passed into State care who refilled the lakes.




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What's There?

Caerphilly Castle is a major tourist attraction and the largest castle in Wales. Although in a ruined state, the substantial remains give a clear indication as to the scale and importance of this key Norman fortress. The impressive ruins are complemented by reconstructions of siege equipment including both weapons and parapet walkways.

Caerphilly Castle Layout. Caerphilly Castle was built to a concentric design which was later imitated by the great Royal fortresses built in North Wales. The substantial water features around the castle were added after Gilbert de Clare saw the effectiveness of such defences at Kenilworth Castle.

Lakes. The vast artificial lakes had both a defensive and economic purpose. The water prevented undermining and also meant any throwing machines were kept back beyond their effective ranges. The lakes would also have been used as a source of fish and eels.

Outer Defences. The fortified dam was key to the defence of the castle. A substantial gatehouse (right) was built to control access whilst defensive towers were added to the wall after the (failed) attack of Morgan ap Maredudd in 1294.

Leaning Tower. The South East Tower leans out at a dramatic angle probably as a result on Parliamentary destruction in 1648. It retains its original medieval crenellations.

East Gatehouse. The Inner Ward East Gatehouse doubled as the Keep and included high-status accommodation.

Great Hall. The Great Hall remains largely unaltered from when it was built by Hugh Despenser the Younger.

Getting There

Caerphilly Castle is a major tourist attraction and accordingly well sign-posted. There is a dedicated castle car park (pay and display) just a short walk from the castle grounds.  Alternatively there are numerous options within Caerphilly town.

Car Park

Crescent Road, CF83 1XY

51.574150N 3.224444W

Caerphilly Castle

Castle Street, CF83 1NZ

51.576206N 3.218738W