The foundations for the castle were [most likely] laid in 1067, the year following William the Conqueror's coronation in England. Its architect was William FitzOsbern, the Norman Lord of Breteuil, Lord of Strigiol (Chepstow) and the Marches, and Earl of Hereford. It is probably the first Medieval stone-built castle in Britain, and is similar to 11th century examples in Normandy. Its stone construction can be attributed to its great military significance. It is believed the Roman Road crossed the Wye somewhere near here, though no proof has been found regarding a possible Roman Castle.

Fitz Osbern's castle had two stories, with the entrance well above ground level. Although it has been altered slightly, it is substantially the same as when it was built. The keep sits on the narrowest part of the ridge, and survives remarkably well. The current entrance is to the right hand side, just before the archway leading to the barbican. It is below the original floor level - into what was probably a cellar. Directly down over the cliff is the river harbour where supplies coming up from Bristol could be hoisted up. This would have been much safer than delivering supplies by land where the Welsh could ambush them. There is also a well, which supplied fresh water. Not only was there a magnificent keep, but also a walled enclosure adjacent to it on the East side.

The lack of windows on the North and West faces of the Castle gives us a good indication that the Welsh were not friendly towards the Earl of Hereford and his men, as any missiles would have to reach above the height of the keep if they were to gain access. This is in stark contrast with the naturally well protected south face, which has many large windows.

After Fitz Osbern's death in 1071, the Castle passed to his son Roger de Breteuil, who not long after took part in an unsuccessful rebellion. He lost the Castle to the crown as a result.

The estates were granted to Walter FitzRichard in about 1115, then to his nephew Gilbert Strongbow and then Gilbert's son & heir, Richard Strongbow. The castle development continued, though it is unclear whether the Strongbows built the Barbican.

William Marshall, Earl of Pembroke, succeeded to the estate at the end of the 12th century, first the father then the son of the same name. Like Fitz Osbern, the Earl of Pembroke was a renowned Norman Castle-builder. He had much experience of military architecture in France, and this was put to good use at Chepstow.

The Curtain wall was strengthened, and two outwardly-projecting towers were built. these towers have arrow slits, and are one of the earliest examples of this type of defence. The entrance to the castle at that time was by a simple doorway set into the curtain wall, which is still present. Marshall's sons continued to improve the castle, and made additions to the keep: in height and with partitions. The remains of a magnificent carved arch on what appears to be the second floor still partially survive. They were also responsible for building the Lower Bailey with its magnificent Gatehouse .

The Gatehouse was very advanced, built in the 13th Century with a design still popular 100 years later. Two drum towers flank the gate, which is topped by a Meurtrière (murder hole), which was used not only to douse potential invaders with boiling water (oil was too expensive) and sand heated to near-melting point, but also to souse any fires/incendiaries that attackers may have used to try and burn through the wooden gates. Meurtrières are also found in the Barbican and Marten's tower (the latter for intruders who had already breached the castle wall and were now trying to assault the tower itself)

The strongly defended barbican was constructed at the upper end of the castle at about this time. It has a gatehouse of the older (but still popular) design with a rectangular tower pierced by the passage entrance.

Roger Bigod III undertook the next major phase of building work. Bigod is regarded as being one of the greatest magnates of his day, and the splendid hall block on the North side of the lower bailey was built during his incumbency. It is also possible that Bigod was the builder of the Barbican.

The Hall has additions and modifications possibly dating to the 16th century and the time of William Herbert, Earl of Pembroke, though they could be earlier. The cellar opens out over the river, so supplies could be hoisted up from the boats below - the same way the castle was provisioned some 200 years before.

Across the courtyard is Marten's Tower (named after the regicide, Henry Marten, who was imprisoned there in comfort after the restoration). It is considered to be one of the greatest 'D'-shaped mural towers built during the thirteenth century. The apartments must have been extremely impressive, and a great deal of the internal wall plaster is still intact. The roof and floors were intact into the early 19th century.

As a military stronghold in Medieval times, the castle was virtually impregnable. However, with developments in Military tactics during the Renaissance, and most noticeably the use of gunpowder in small arms and siege weaponry, the castle lost its advantage. This is particularly noticeable when we look forward in time towards the English Civil Wars, and the breaching of the curtain wall, firstly in 1645, and again in 1648.

REFERENCES
Bates, D. (1989) William The Conqueror George Phillip Ltd, London
Brown, R.A. (1977) English Castles Book Club Associates UK
Brown, R.A. (1984) The Architecture of Castles: A Visual Guide B.T. Batsford, London
Evans, H.A. (1914) Castles of England and Wales Methuen & Co, London
Hiling, J.B. (1976) The Historic Architecture of Wales University of Wales Press, Cardiff
Kenyon J.R. (1996) Medieval Fortifications Leicester University Press, London
Nelson, L. H. (1963) The Normans in South Wales, 1070 to 1171 University Microfilms Inc., Ann Arbor, Michigan
Walker, D. (1990) Medieval Wales Cambridge University Press, Cambridge
Warner, P. (1980) Famous Welsh Battles (editor) William Collins Sons & Co. Ltd, Glasgow
Williams, A. (1995) The English and the Norman Conquest Boydell Press, Woodbridge
Wood, J.G. (1910) The Lordship, Castle & Town of Chepstow, otherwise Striguil, with an appendix on the Lordship of Caerleon Mullock & Sons, Newport