For most of the medieval period, Eryri was not simply a mountain landscape — it was the heartland of the most powerful Welsh kingdom, Gwynedd, and the base from which the princes who came closest to creating a unified Welsh polity operated. The mountain fastnesses that now challenge recreational walkers served as a natural fortress from which English armies were consistently driven back until the late 13th century.
Llywelyn ap Iorwerth — Llywelyn Fawr (the Great)
Born around 1173, Llywelyn ap Iorwerth ruled Gwynedd from 1194 and, at the height of his power, commanded the fealty of virtually every Welsh lord. Known as Llywelyn Fawr — Llywelyn the Great — he unified the fractious Welsh kingdoms under a single authority, negotiated the Treaty of Worcester (1218) with the English crown recognising his pre-eminence in Wales, and created the conditions for Welsh political identity to be expressed at a national level.
Llywelyn based himself at Aber Garth Celyn (Abergwyngregyn, on the north coast) and at Dolbadarn Castle above Llanberis. Dolbadarn — the round tower still standing above Llyn Padarn — is a Welsh castle, built by Welsh craftsmen to Welsh architectural specifications, predating Edward I's ring of English fortresses by half a century. Llywelyn died at the abbey of Aberconwy in 1240.
Llywelyn ap Gruffudd — Llywelyn Ein Llyw Olaf (Our Last Leader)
Llywelyn's grandson came closest of all to establishing Welsh sovereignty recognised in international law. The Treaty of Montgomery (1267) acknowledged him as Prince of Wales — a recognition by the English crown of his authority over the other Welsh lords. The accession of Edward I (1272) changed everything. Edward's military campaigns of 1276-77 and 1282-83 were designed not merely to defeat Llywelyn but to permanently extinguish Welsh political independence.
The second campaign ended on 11 December 1282, when Llywelyn was killed in a skirmish near Builth Wells in mid-Wales — reportedly ambushed while separated from his main force. He is remembered as Llywelyn Ein Llyw Olaf: Our Last Leader. Llywelyn's brother Dafydd continued the resistance until his capture in June 1283; he was executed at Shrewsbury — the first person in recorded history to be executed for high treason. With his death, the independence of Gwynedd ended.
The Welsh Castles
The Welsh princes built their own castles — smaller, less systematically engineered than Edward's fortresses, but strategically positioned in the mountain landscape. Dolbadarn (Llanberis) controls the southern end of the Llanberis Pass. Dolwyddelan (in the Lledr valley above Betws-y-Coed) guards the mountain route from Gwynedd to the east. Both are dramatically positioned and worth visiting — the contrast with Edward's concentric fortresses tells you something about the difference between indigenous defence and colonial imposition.
Edward's Iron Ring
Edward I's response to the difficulty of subduing Gwynedd was to build a ring of fortresses around the mountain core — Caernarfon, Conwy, Harlech, Beaumaris — combined with new English settler towns. The four castles are jointly a UNESCO World Heritage Site and architectural masterpieces of medieval military engineering. They are also, unambiguously, instruments of colonial control: built by foreign craftsmen (James of St George, the master builder, was Savoyard), garrisoned by English soldiers, and designed to project English power into a landscape that had been thoroughly Welsh for centuries.
Independently written — Snowdon.com