Welsh title of 12th-century pseudo-historical tale known in English as ‘The Dream of Macsen Wledig’, ‘Prince Maxen's Dream’, etc. The historical figure at the centre of the story, Macsen Wledig, is the Spanish-born Maximus, or Magnus, Clemens, a Roman emperor, ad 383–8. Although described as a usurper by Roman historians, he was a hero to the British (i.e. Welsh) for helping them to throw off the yoke of Gratian (383). His reign came to an end when he was slain by Theodosius the Great at Aquileia. His name is cited in Gildas and Nennius (9th cent.), and he appears as the founder of many dynastic and ecclesiastical families.
Macsen Wledig, the Emperor of Rome, dreams one night of a lovely maiden in a wonderful, far-off land. Awakening, he sends his men all over the earth in search of her. With much difficulty they find her in a rich castle in Britain, and lead the Emperor to her. Everything he finds is exactly as in his dream. The maiden, whose name is Elen (1), accepts and loves him. Because Elen is found a virgin, Macsen gives her father sovereignty over the island of Britain and orders three castles built for his bride. Elen is probably also based on a historical figure, Elen Luyddog of Segontium (Carnarvon), who was in reality Macsen's (Magnus's) wife. In Macsen's absence, a new emperor seizes power and warns him not to return. With the help of men from Britain led by Elen's brother Cynan, Macsen marches across Gaul and Italy and recaptures Rome. In gratitude to his British allies, Macsen rewards them with a portion of Gaul that becomes known as Brittany.
Some commentators see a link between this Welsh dream and the aisling, conventionalized dream poetry, often with political intent, in Irish tradition. Edited in Welsh by Ifor Williams (Bangor, 1928); English translations are included with several editions of the Mabinogi/Mabinogion.