Commander of the Roman Forces in Britain, and the Emperor of Britain and Gaul
Magnus Maximus was the commander of the Roman forces in Britain in AD 383. He successfully usurped the throne from the emperor Gratian, and the following year become emperor of Britain and Gaul.
Magnus Maximus is relevant to Welsh history as the commander who ended the Roman military presence in Wales – probably within the decade following 383. However Segontium, the Roman fort at Caernarfon, may have been occupied until AD 393.
According to Welsh legends, in which Magnus is known as Macsen Wledig, he is said to have married Elen (or Helen), daughter of a chieftain based at the fort of Segontium in Caernarfon. This legend, ‘Breuddwyd Macsen’ (‘Macsen’s dream’) is told in the medieval tales of the Mabinogi (Mabinogion). The story describes how Macsen dreams of Elen and sends out his troops to find her – eventually discovering Elen at Segontium.
Geoffrey of Monmouth is also known to have written about Magnus Maximus. There may well have been earlier Welsh tales about this character, but the legend of his dream, and the connection with Elen and Segontium, has no historical basis.