British Iron Age and Roman sites have been excavated and coins and ornaments discovered, especially by the 19th-century antiquarian William Owen Stanley. After the Roman departure from Britain in the early 5th century, pirates from Ireland colonised Anglesey and the nearby Llŷn Peninsula. In response to this, Cunedda ap Edern, a Gododdin warlord from Scotland, came to the area and began to drive the Irish out. This was continued by his son Einion Yrth ap Cunedda and grandson Cadwallon Lawhir ap Einion; the last Irish invaders were finally defeated in battle in 470. As an island, Anglesey was in a good defensive position, and so Aberffraw became the site of the court, or "Llys", of the Kingdom of Gwynedd. Apart from a devastating Danish raid in 853 it remained the capital until the 13th century, when improvements to the English navy made the location indefensible. Anglesey was also briefly the most southerly possession of the Norwegian Empire.