The Normans led by Robert Fitzhamon first entered Glamorgan about 1100 AD. He split Glamorgan into knights fees amongst those who gave him military service. Cardiff was kept by Robert himself as were Margam and Kenfig.

It was during the reign of King Stephen (r.1135-1154) that the first castle was built at Kenfig (c.1140). The early Norman castle would have been constructed of wood on a motte or mound surrounded by a moat. The structure stood on the edge of the town which was itself surrounded by an outer moat and bailey.

Kenfig was controlled by Normans and was an important maritime trading town. Consequently, the Welsh thought of it as an economic and political threat and attacked it many times throughout history.

There were nine attacks upon the castle and adjoining town with a case for at least another two within a period of 300 years. The first recorded attack of its kind was on 13 January 1167 - the result of the early attacks was that the wooden castle was replaced by a stone tower about 1185.

There are eight listed attacks above – there appears to be some discrepancies surrounding dates listed by Kenfig Society and those supplied by BCBC Education documents. These are to be addressed in the near future.

The ruins of the castle were excavated in 1924 by the Aberafon and Margam Historical Society confirming it it be a late 12th Century structure, although a lot of later reconstruction had been done as a result of further attacks. Details of the castle were noted - the tower or keep was about 45ft square with walls 11ft thick, judging from the basement dimensions it would have been about 60ft high.

The Keep would have provided the living quarters for the town constable who was in charge of the defence of the castle. it stood at the north corner of an enclosure, a quarter of an acre in area. The Keep was located so that it could defend an important ford or crossing place on the river.

A 14ft deep moat gave further protection to the castle. The outer bailey enclosed 11 acres of land and most of the town. The excavations yielded only a few finds, these included.

The original castle was probably made entirely of wood. The inner ward contained the keep is roughly 37m in diameter and surrounded by a deep moat - 18m across, into which the adjoining river could be diverted. Entrance to this ward was in the SW corner – this led out onto a drawbridge that gave access to the outer ward on the opposite side of the moat.

The keep incorporated elements of a Roman nature to include bricks, tiles, and opus signum (Roman Concrete).

The most unusual feature of the castle is the size of its outer ward, estimated to be between 8-11 acres in extent. It lay to the south and west of the inner ward and the large area it enclosed is generally believed to be the site of the Kenfig town. The earliest town would have occupied much of this enclosure, however, by 1154 this had been moved outside to the south. As in other castles this outer enclosure would have contained the living quarters of the constable and his garrison, stables and possibly a chapel. Once the town moved it would have been far larger and probably retained for use as a forward base for military forces in operations further west where much of the local unrest during the 12th & 13th centuries originated.