An Iron Ring of Castles is in many ways just like it sounds: a series of castles built around Wales to control the populace after the death of Llywelyn ap Gruffydd, the last Prince of Wales. In the 1270s and 1280s primarily, Edward I began the construction of this ring. The castles were focused in the north, in Gwynedd, since that region had always been a hotbed of Welsh resistance and resentment of English authority, and it was there that he built some of the most impressive monuments to his victory. http://www.castlewales.com/edward1.html
He began in the northeast with three castles: Hawarden, Flint, and Rhuddlan, all built before the 1282 war. Hawarden was the first castle attacked by Dafydd ap Gruffydd on Palm Sunday, 1282, when he started what became the final war with England. Edward began Flint in 1277, bringing in up to 2300 English workers to build it. Llywelyn ap Gruffydd submitted to Edward I at Twthill, the old timber castle at Rhuddlan, after which Edward immediately pulled down the old structure and began work on the present, massive, stone castle, built at the first usable ford of the Clwyd River, south of the sea.
Following along the north coast, come Conwy, Beaumaris, and Caernarfon, bringing the string of powerful castles across the coast of north Wales to six, within a stretch that was fewer than 60 miles as the crow flies. Source for the map: http://www.timeref.com/castedwd.htm
Conwy was begun in March of 1283, before the death of Dafydd ap Gruffydd and is located on the west bank of the Conwy river, which is of more than symbolic significance. It was the Conwy River that was the barrier between east and west Gwynedd, and the difficulty in forcing it that delaying Edward’s conquest of Wales. With a massive castle on the west bank of the river, he gained a permanent foothold in Snowdonia and the patrimony of the Princes of Gwynedd.
Beaumaris was built on Anglesey, near the ruins of Llanfaes Abbey (which the English destroyed), which had been patronized by the Welsh Princes. At one point, the sarcophogus of Joanna, Llywelyn Fawr’s wife, was used as a horse trough, but is now on display at a nearby church (St. Mary’s). The castle wasn’t built until 1295, as a result of the rebellion in late 1294 by Madog ap Llywelyn. The entire population of Llanfaes was moved in order to build it, and the Welsh royal palace/administrative center (called a llys) destroyed.
Edward built Caernarfon (spelled Carnarvon by the English) beginning in May 1283. Like other planted English communities associated with Edward’s castles, English settlers were brought in and the castle became Edward’s primary seat in Wales. It was here that his son, Edward II was born–intentionally–to give credence to Edward I’s later naming of him the Prince of Wales.
The final two castles in Edward’s building program are Aberystwyth and Builth/Buellt. Edward began Aberystwyth on the west coast of Wales in 1277 as a concentric castle (near/on the foundations of much older castles), but conspirators of Dafydd ap Gruffydd attacked it on Palm Sunday, 1282, damaging it badly. Thus, it wasn’t until the Welsh defeat at the end of 1283 that construction began again, finishing in 1289. Today, it is one of the more crumbled of Edward’s castles, although not as damaged as Builth in Powys, of which only grassy mounds remain.
Like Aberystwyth, Edward began building Builth Castle in 1277, in response to the defeat of Llywelyn ap Gruffydd. It was near this castle, in fact, that Llywelyn was set upon and murdered in December of 1282.