Right: The Castles of North Wales and the Welsh Wars of Independence

Edward I's fearsome Iron ring of colossal fortresses represents Europe's most ambitious and concentrated medieval building project, designed to prevent the recurrence of two massively expensive military campaigns. After Edward's first successful campaign in 1277, he was able to pin down his adversary Llywelyn ap Gruffydd ("The Last") in Snowdonia and on Anglesey. This gave him room and time enough to build the now largely ruined castles at Flint, Rhuddlan, Builth Wells and Aberystwyth, as well as to commandeer and upgrade Welsh castles, Edward's first attempt at subjugation.

Llywelyn's second uprising, in 1282, was also ultimately unsuccessful, and Edward, determined not to have to fight a third time for the same land, set about extending his ring of fortifications in an immensely costly display of English might. Together with the Treaty of Rhuddlan in 1284, this saw the Welsh resistance effectively crushed. The castles at Harlech, Caernarfon and Conwy, through nearly contemporary, display a unique progression towards the later, highly evolved concentric design of Beaumaris.

All this second batch, including the town walls of Caernarfon and Conwy, were the work of the master military architect of his age, James of St. George d'Esperanche, whose work is now recognized with UN World Heritage Site status. Each of the castles was integrated with a bastide town, an idea borrowed from Gascony in southwest France, where Edward I was duke - the town and castle mutually reliant on each other for protection and trade. The bastides were always populated with English settlers, the Welsh permitted to enter the town during the day but not to trade and certainly not carrying arms. It wasn't until the 18th century that the Welsh would have towns they could truly call their own.

The Edwardian castles of North Wales were nearing completion when the revolt of 1294-5 broke out. Their garrisons were depleted by the king's expedition to Gascony. Several, including Cardigan and Caernarfon, were besieged, but the English control of the sea restricted the spread of the revolt. Castles held out as long as provisions could be brought by ship. Aberystwyth, Conwy and perhaps Criccieth and Harlech were provisioned from Bristol and Ireland. During the winter - not an unusual time for campaigning - the king's forces pressed into Gwynedd. Caernarfon was relieved, and in the spring of 1295 work began on the last of Edward's castles, Beaumaris.

Edward experienced the greatest difficulty in paying for his building program. Its true monetary cost cannot be known. Over 12 years he spent L60,000 (about L33 million in today's terms), more than 10 times his annual income, on building castles and walled towns at Conwy, Caernarfon, Beaumaris and the refurbishment of Llywelyn's castle at Criccieth. This integrated program - each borough defended by its castle, and each castle accessible by sea - has left Wales with a legacy of medieval military architecture of truly international importance. (Artwork above right by Bryan Leister)

The Medieval Castle in England and Wales, N. J. G. Pounds, Cambridge University Press, 1994.

Wales - The Rough Guide, Mike Parker and Paul Whitfield, Rough Guides Ltd, London, 1994.

The definitive account of Edward's campaigns in north Wales has long been John E. Morris, The Welsh Wars of Edward I.