Like so many Castles in Wales, Kidwelly was built by the Normans to defend against the Welsh. You would have thought that the Normans would have realised that this was a futile gesture because the Welsh were not prepared to learn to speak French. I’m sure there were other reasons they were disgruntled about the invasion but this seems like a fairly good one to me.
The remains of the castle we see today were constructed between 1111 until about 1476. It saw quite. bit of action in the twelfth century, falling to the Welsh on a number of occasions. In 1403 Owain Glyndŵr unsuccessfully besieged the castle with the aid of troops from France and Brittany. After just three weeks the Norman Army turned up and put a stop to these shenanigans. The gatehouse was damaged and was later rebuilt on the instructions of King Henry V.