In 1276 Edward I declared war on Llywelyn, the Prince of Wales. The English king advanced into north Wales building a series of castle on the coast. These castles were designed and built by James of St. George, Edward's master castle builder. James rebuilt the castle at Aberystywth at a new location. Being located near the coast meant the castle could be resupplied by ship, a safer means of getting food and men to the castle than across rugged Welsh countryside.
The castle remained in English hands until the revolt of Owain Glyndwr. A dispute over land resulted in a full scale rebellion against the English in Wales. Let by Glyndwr the Welsh captured many castles in North Wales including Aberystwyth. In 1407 Prince Henry (the future king Henry V) laid siege to the castle and captured it in 1408.
English Civil War
Aberystwyth Castle was held by Royalists during the English Civil war but was captured by the Parliamentarians under the command or Colonel Rice Powell. In around 1647/49 the castle was destroyed on the order of Oliver Cromwell to prevent it being used again as a fortress. Sometime after this silver coins were minted on the site of the castle using silver ore that was mined locally.