Beaumaris Castle

After campaigning throughout North Wales, King Edward I ruthlessly stamped his authority on his newly conquered territories. He didn’t just build castles, he created towns to go with them wiping out any Welsh settlements in his way. He had already built at Conwy, Caernarfon, Harlech and other sites ringing Snowdonia. Collectively these castles and towns form a World Heritage Site

castle interior - unfinished gatehouse
castle interior – unfinished gatehouse (J Conway)

Beaumaris was the last to be built, here Edward and his architect James of St George took full advantage of a flat site with no restrictions on design – the ‘beau marais’ or ‘beautiful marsh’ – beside the Menai Strait (see photo below) . The result was a fortress of immense size and near-perfect symmetry. No fewer than four concentric rings of formidable defences included a water-filled moat with its very own dock. The outer walls alone bristled with 300 arrow loops. However, the castle was never finished as Edward’s wars elsewhere distracted him and emptied his coffers.

aerial view of Beaumaris castle  and town
aerial view of Beaumaris castle and town (J Conway)

The existing Welsh settlement at Llanfaes had been the seat of Llywelyn Fawr, his ‘llys’ [royal palace] and a busy port trading with other towns in Britain and on the Continent. Edward’s troops demolished Llanfaes and many of the residents were forcibly resettled in a new town at Newborough. The new English town of Beaumaris received its first royal charter in 1296 and by 1305 contained 132 ‘burgages’ or properties – making it the biggest borough in North Wales. It remained the most important town on Anglesey until relatively recently (see GeoMon’s town trail for a wander round the town and its environs).

Even in its unfinished state Beaumaris Castle combines the beauty of its perfect symmetry with an overwhelming sense of ruthless power. The castle is built mainly of stone quarried at Penmon; Carboniferous limestone [of various types], sandstone and conglomerate. the varying colours of these rocks allowed for a “checkerboard” pattern in the construction. Early [lower] parts of the walls are built of random stones from the local boulder clay.

supposed checker pattern from using limestone and sandstone
supposed checker pattern from using limestone and sandstone (J Conway)

The site – like all Edward’s castles – was built to be supplied from the sea. like Harlech it is no longer directly connected to the sea but its interesting to speculate on the combined effects of isostatic rebound and climate change! Isostatic rebound is where land depressed by the enormous weight of Ice Sheets and glaciers rises back to its original position relative to sea level. Beaumaris will have risen some 700mm since its construction lifting it above sea level – but now climate induced sea level rise will bring sea level relative to the castle back to where it was in Edward’s day sometime this century. We may once again sea ships sailing into the castle dock!

Evidence of sea level rise can be seen in the new sea wall and closures along the front of the Green.

new stainless steel flood gates
new stainless steel flood gates (J Conway)
new limestone sea wall incorporating stainless steel flood gates
new limestone sea wall incorporating stainless steel flood gates (J Conway)

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