Geoffrey of Monmouth published his Historia Regum Britanniae in Oxford, England, which included a lengthy section of prophecies attributed to the wizard Merlin. These prophecies, written as political allegory, were quickly taken as genuine predictions of future events. They were used by successive English kings, including Henry II and Edward I, to legitimize their claims to rule over all of Britain, shaping royal propaganda for centuries.

Geoffrey's work created the modern literary figure of Merlin and established a tradition of political prophecy that would dominate English literature for centuries. The Prophecies of Merlin were widely read, translated, and adapted, influencing the Arthurian romances of Chrétien de Troyes and later the works of Malory and Tennyson, embedding prophecy deep in the English literary consciousness.