Macsen, Maxen, Maximian, Maximianus, Maximien
A Spanish-born Roman general who, in the late fourth century, served the Roman empire as Dux Britanniarum, or commander of the Roman army in Britain. He may have led a campaign against the Picts around 370. Maximusís soldiers apparently elevated him as their emperor, and in 383, they convinced him that he had a right to the Roman Empire itself. Maximus crossed the channel into Gaul to begin an invasion. He conquered parts of Europe, and his allies murdered Gratian, the western Roman emperor. Though he had effectively conquered Rome, he did not yet occupy the capital. In 388, while he was camped in Aquileia (Acquileia), he was attacked, captured, and executed by Count Theodosius.
The chronicles style Maximus as a king of Britain. Gildas and Nennius describe his rule as tyrannical, but Geoffrey of Monmouth (who erroneously calls him Maximian) gives him certain credit for holding back the barbarian invasions. Welsh tradition, too, heroifies Maximus in the character of Macsen. The chroniclers seem to agree, however, that Maximusís hubris led - at least partially - to the downfall of Britain. By siphoning all of Britainís warriors to wars in Gaul, and by then establishing them there, Maximus effectively depopulated the island of its defense, leaving it open to invasions by Picts and continental barbarians.
In the Welsh story called The Dream of Macsen, Maximus, who is already the Emperor of Rome, dreams of a glorious island far to the west (Britain) and of a beautiful woman to be found there. Upon awakening, he sets out on a search for the land of his dreams, eventually coming to Segontium in Wales and meeting the woman, Elen of the Hosts.
Maximus marries Elen and, as he has conquered Britain in the process of finding her, he bestows the land upon her father, Eudaf. Macsen remains in Britain for seven years, after which the Roman citizens elect a new emperor. Upon hearing of this, Macsen raises an army of Britons - led by Elenís brothers, Cynan and Gadeon - travels back to Rome, and, unlike the Maximus of the chronicles, re-captures the empire. In Welsh tradition he is known as Macsen Wledig.