Macsen Wledig was Emperor of Rome, and he was the handsomest and wisest of men, and the best fitted to be Emperor of all who had gone before him.
The Dream of Macsen Wledig, trans. Gwyn Jones
Macsen has a dream of a beautiful woman on a throne in a hall in a castle in far-off Wales, and he sends someone to Wales, and there she is in far-off Wales, on the throne, in the hall, in the castle. And she says if he wants her he has to come and find her on the throne in the hall in the castle in Wales, and he comes and finds her, and they fall in love. He marries her, and he spends seven years in Britain. While he is away, another Emperor rises in Rome; the usurper sends a threat to Macsen, who rises to the threat, and with an army of invincible Britons, he sweeps across the Western Empire, and finally lays siege to Rome, and takes it, and lives there with Elen his empress, and never returns to Britain.
In the late fourth century, a charismatic Roman general named Magnus Maximus, born in Spain, came to command the soldiers in Britain. In 383CE he staked a claim on the Empire. He took a British army to Europe and never returned. And among the Britons, of whom the survivors would be the people of Wales – Wales is one of the two oldest living languages in Europe (the other being Basque) – the story of course grew.
Although modern books about the time are pretty definite, what actually happened is really quite vague. Very little is written about this period. There are maybe three primary accounts of this time. They are not detailed.
Maximus, an energetic, upright man worth being called Augustus led an uprising in Britain that crossed to Gaul. He had been declared Emperor against his will. The Emperor Gratian, terrified by the sudden invasion, planned to escape to Italy, but Maximus trapped him and killed him, and then drove Gratian's brother the Emperor Valentinian out of Italy. Valentinian took asylum in the East, where Theodosius accepted him as a son and restored to him his imperial dignity.
Orosius, History in Opposition to the Pagans, VII. 34. 9-10
To explain: after Valens died in 378, The two legitimate successors were his nephews Gratian, then 19, and his younger brother Valentinian, who was maybe 7. With these boys too young to really be able to run the show, what we think happened is that Theodosius, the capable general who cleaned up Valens's mess, got given the job as co-Emperor. Maximus had the 24-year-old Gratian murdered and let the boy Valentinian escape to Theodosius.
Theodosius, an old comrade, initially accepted Maximus's claim to be Western Emperor for a few years, but eventually came back with Valentinian and defeated him in a civil war in 388.
First thing you need to know is that Orosius is the actual pits. He wrote his history book with a clear agenda (see if you can guess what it was) as the Official Companion to Saint Augustine's theological blockbuster City of God. It's a slog, I can tell you. In this year, this happened, and then in this year, this happened, and then in this year this happened... It's just dull. The one good thing about Orosius is that he dates everything, year... after year... after year... Seriously, it's excruciating, but at least it gives you an idea of when stuff happened.
The other historians – Zosimus, Socrates Scholasticus, Sozomen – aren't really any better. Zosimus, who comes from the sixth century, but who had access to writing about the time that we don't, does say that Maximus's claim that he never intended to become Emperor was a flat lie. A sixth-century British historian named Gildas describes Maximus as a "high-handed tyrant" and celebrates his beheading. But you see, these sources are far away in time. They are not clear-cut. They are a sign of history collapsing.
Ammianus Marcellinus's story leaves off before Maximus made his play, but he mentions Maximus as a leader in the Gothic Wars. He calls him "reckless" and "brutal" (XXXI. 4. 9). That's it. One of the Latin Panegyrics (12) describes Maximus as a tyrant, and the murderer of Gratian. Some letters from Ambrose, Bishop of Milan, an accomplished diplomat, talk around him but not about him (I found a great list of most of the things written about Magnus Maximus here. There is not a whole lot. The only things really missing are the references in Ambrose). The statues and coins show someone handsome, clean-cut.
Maximus isn't counted in the lists of Emperors. He's called a "usurper." A usurper is normally thought of as an illegitimate claimant to a throne that already has someone else sitting on it, but that's not the whole story. A usurper is someone who claims an occupied throne and loses. For example, the only reason Constantine is called an Emperor and Maxentius is called a usurper is that Maxentius lost. But both of them claimed the throne illegally. Constantine won the name Emperor because he was the last man standing.
So was Maximus Emperor of Rome? Sort of. That's the only really honest answer.
The one account of Maximus that gives some idea of what he's like comes from Sulpicius Severus, who is mostly interested in how Magnus Maximus interacted with his hero, (Saint) Martin of Tours.
This is most of Chapter 20 of Sulpicius Severus's biography of St. Martin, the former soldier turned conscientious objector, bishop and miracle worker. Just to give you an idea, in Chapter 19, Martin miraculously heals someone with a letter. In Chapter 21, he meets angels. In Chapter 22, he gets into a personal argument with Satan himself. And it goes on. There's this parade of miracles and prodigies, and in the middle of it, this account of the saint's visit to the court of Magnus Maximus (the bit I missed out is about Martin not flattering Maximus at a party). And that is strange!A number of bishops had come together to the court of Maximus, who was a man of fierce character, and who about that time celebrating his victory in the civil war. Everyone could see how disgracefully people flattered him. And the dignity of the priesthood had become degenerate and submissive and took second place to the royal court. Only Martin asserted his religious authority. Even if he needed something from the Emperor, he commanded it rather than asked. Although he was often invited to dinner, Martin kept away, saying he wasn't going to share a table with someone who'd taken away the life of one Emperor and the kingdom of another.In the end, Maximus swore that he hadn't assumed sovereignty of his own accord. He had just done what he had to, he said, and he had defended the Empire because the soldiers had forced him to do it. He said that he'd not missed out on God's favour – God had given him an almost impossible victory, and he had only ever killed his enemies on an open battlefield. Regardless of whether he brought Martin round by his reasoning or his pleas, Martin came to Maximus's dinner party, and the Emperor was very pleased that he had won this point...Martin had predicted long before to Maximus that if he invaded Italy – which he did mean to do – as an act of war against Valentinian, then he should know that he'd be the winner of the first battle, but that he'd die shortly afterwards. And, as we have seen, this is exactly what happened. For on Maximus's first attack, Valentinian fled, but about a year afterwards he got his strength back, and he captured and killed Maximus inside the walls of Aquileia.Sulpicius Severus, The Life of Saint Martin of Tours, XX.1-3, 7-9.
Sulpicius Severus is basically contemporary, but even so, his is a world of demons and monsters, angels and miracles. And in the middle of that, this story about the saint behaving with dignity in the face of the Emperor or pretender or usurper or whatever he is. The man was barely even in the ground when Severus was writing this, and Magnus Maximus had already become the province of myth.
Magnus Maximus is not knowable; he is not given a wealth of biographical material, and much of it is fiction, subjective opinion, or myth. None of his own words survive; only one writer whose works survive (Ambrose) even met him and practically all he says is, "I met him."
With a character about whom so little was written, who was so obscure, and so inaccessible to the people on the ground, it makes perfect sense that the charismatic Roman leader who swept in from nowhere and took the British army with him on a campaign of conquest, never coming back, might be transformed into a hero who falls in love with a Welsh princess he saw in a dream and goes to take Rome with the aid of the Britons, who no one can beat in a fight. With so little written, some of it almost contemporary and already in the province of myth, it seems that he could do nothing else but become the Emperor of a distant land's dreams.