The castles of Beaumaris, Harlech, Caernarfon and Conwy are located in the former principality of Gwynedd, in North Wales. These castles are examples of the building of strategic castles by Edward I (1272–1307) and the military architecture of the time.
Edward I extended and completed and completion a plan which he inherited from his father, Henry III. Edward I merely strengthened the strategically placed castles like Aberystwyth, Builth, Cardigan, Carmarthen and Montgomery. But it was North Wales that he saw as the greatest danger, and it was in North Wales that he concentrated his investment. All castles west of Chester had suffered from attack by the Welsh. The king here not only repaired existing castles, but also built new, state of the art castles in strategic locations. The four great castles of North Wales that exist today, and are the World Heritage Site (Conwy, Harlech, Caernarfon & Beaumaris) were built by him from scratch.
Edward I's had had to embark on two expensive military campaigns against the Welsh. After his first campaign in 1277, he pinned down the Welsh under Llywelyn ap Gruffydd in Snowdonia and on Anglesey. Llywelyn's second uprising, in 1282, was also unsuccessful, and Edward wished to avoid a third campaign against the Welsh. The castles at Beaumaris, Harlech, Caernarfon and Conwy were his way of fulfilling his aim.
Each of the castles was integrated with a town, so the town and castle were mutually reliant on each other for protection and trade. The towns were populated with English settlers, the Welsh permitted to enter the town during the day but not to trade or carry arms.
The castles were nearing completion when the revolt of 1294-5 broke out. Their garrisons were reduced virtue of by the king's expedition to Gascony. Several, including Cardigan and Caernarfon, were besieged, but the English control of the sea allowed the castles to withstand their sieges. During the winter the king's forces pushed into Gwynedd. Caernarfon was relieved, and in the spring of 1295 work began on the last of Edward's castles, Beaumaris.
Edward was nearly bankrupted by the expense. Over 12 years of building, he spent a total of around 10 times his annual income, on building castles and walled towns in Wales. However the quality of the building - each town defended by its castle, and each castle supplied by sea - has left Wales with a legacy of medieval military architecture of international importance.
World Heritage Sites in Britain