After killing the Roman consul-elect, the Boii (a Celtic tribe occupying part of the Po valley)

Transplanted from his pagan Irish origin, Brân " has become King of the island of Britain, crowned in London and has acquired the Christian epithet bendigeid, 'Blessed'....He led an expedition to a foreign land and was victorious. Nevertheless, he was wounded in the foot with a poisoned javelin,(is that like a pitch fork in my foot as a child) and, though no causal nexus is mentioned, the islands of Ireland and Britain were rendered desolate. Brân commanded his followers to cut off his head and to travel with it, first to Harlech and then to the island of Grassholm. Obeying his commands, they spent seven years at Harlech, regaling themselves with meat and drink. Then, setting out for Grassholm, they found there a fair royal place, a great hall, overlooking the sea. That night they spent there without stint, and we may infer that they continued to feast, as they had at Harlech, for eighty years, in the company of the uncorrupted head of Brân. This was called the Hospitality of the Wondrous Head."
http://www.mystae.com/restricted/streams/gnosis/avalon.html