Anglesey, known to the Welsh as Ynys Môn and to the Romans as Mona, is an island county off the north-west coast of Wales, separated from Caernarvonshire by the narrow tidal strait of the Menai and washed on every other side by the Irish Sea. Eighteenth-century surveys measured it at twenty-three miles long and sixteen broad, some 200,000 acres divided into six hundreds, with just two market towns and a population of around 12,000 lying within the diocese of Bangor. Despite its rocky, wind-scoured appearance, antiquarian writers noted that Anglesey's soil was far more fertile than it looked, so productive of corn, cattle, fish and fowl that the Welsh themselves called it Môn Mam Cymru, the Mother of Wales, for its role in provisioning the mainland.
Anglesey's history stretches back further than almost anywhere in Britain: it was the last stronghold of the Druids, whose sacred groves the Roman general Suetonius Paulinus destroyed in a famous campaign in AD 60, an assault vividly recorded by Tacitus, before the island was fully absorbed into the Roman province under Agricola a few years later. Later occupied in turn, tradition held, by Irish raiders, Anglo-Saxon plunderers under Æthelred and Viking Norsemen, the island was finally brought under direct English control by Edward I in the thirteenth century, when it first took the English name Anglesea, or 'the English island', a name that has stuck ever since despite the island's thoroughly Welsh character.
Beaumaris Castle, the last and most technically sophisticated of Edward I's great Welsh castles, begun in 1295, stood as Anglesey's principal antiquity, alongside the ancient collegiate church at Holyhead, itself founded, according to tradition, in the seventh century. Separated from the mainland only by the narrow Menai Strait, later spanned by two of the most celebrated bridges of the industrial age, Anglesey has retained across many centuries an identity distinct even from the rest of North Wales, rooted in its unusually fertile land and its deep layers of prehistoric, Roman and medieval history.