Petronius Maximus was born in about 396.

Although he was of obscure origin, it is now believed that he belonged to the Anicii family.

Related to later Emperor Olybrius, Maximus was the son of Anicius Probinus,,the son of Anicia Faltonia Proba and Sextus Claudius Petronius Probus, who was Prefect of Illyricum in 364, Prefect of Gaul in 366, Prefect of Italy in 368–375 and again in 383 and consul in 371.

Maximus had achieved a remarkable career early on in his life.

His earliest known office was praetor, held about 411; around 415 he served as a tribunus et notarius, which was an entry position to the imperial bureaucracy, and led to his serving as Comes sacrarum largitionum (Count of the Sacred Largess) between 416 and 419.

From January/February 420 to August/September 421 he was praefectus urbi of Rome, an office he held a second time sometime before 439; as praefectus, he restored the Old St. Peter's Basilica.

He was also appointed praetorian prefect sometime between 421 and 439; it was either during his holding of this post, or during his second urban prefecture, that he was appointed consul for the year 433.

From August 439 to February 441 he held the praetorian prefecture of Italy, then a second consulship in 443.

Between 443 (the year of his fourth prefecture and second consulship) and 445 (the year he is granted the title of Patrician) Maximus has built a forum in Rome, on the Caelian Hill between via Labicana and the Basilica di San Clemente.

During this year, he is briefly the most honored of all non-Imperial Romans, until the third consulate of Aëtius, generalissimo of the Western empire, the following year.

The powerful patricius and magister militum of the West Aëtius is now at the height of his power.

The enmity between Aetius and Petronius Maximus, prefect of Rome in 420 and twice consul, clearly leads to the events that will gradually bring down the Western Roman Empire.

Initially however, the principal beneficiary of this will be Maximus, who, according to the historian John of Antioch, poisoned the mind of the Emperor against Aëtius, resulting in the murder of his rival at the hands of Valentinian III.

John’s account has it that Valentinian and Maximus placed a wager on a game that Maximus ended up losing.

As he did not have the money available, Maximus left his ring as a guarantee of his debt.

Valentinian then used the ring to summon to court Lucina, the chaste and beautiful wife of Maximus, whom Valentinian had long lusted after.

Lucina went to the court, believing she had been summoned by her husband, but instead found herself at dinner with Valentinian.

Although initially resisting his advances, the Emperor managed to wear her down and succeeded in raping her.

Returning home and meeting Maximus, she accused him of betrayal, believing that he had handed her over to the Emperor.

Although Maximus swore revenge, he was equally motivated by ambition to supplant "a detested and despicable rival," so he decided to move against Valentinian.

According to John of Antioch, Maximus was acutely aware that while Aëtius was alive he could not exact vengeance on Valentinian, so Aëtius had to be removed.

He therefore allied himself with a eunuch of Valentinian's, the primicerius sacri cubiculi Heraclius, who had long opposed the general with the hope of exercising more power over the emperor.

Although in 453 Aetius had been able to betroth his son Gaudentius to Valentinian's daughter Placidia, Valentinian feels intimidated by Aetius, who had once supported Joannes against him and who, Valentinian believes, wanted to place his son upon the imperial throne.

Maximus and Heraclius are therefore able to enlist Valentinian in a plot to assassinate Aetius.

The ancient historian Priscus of Panium reports that on September 21, 454, while Aëtius was at court in Ravenna delivering a financial account, Valentinian suddenly leaped from his seat and declared that he would no longer be the victim of Aëtius's drunken depravities.

He held Aëtius responsible for the empire's troubles and accused him of trying to steal the empire from him.

When Aëtius attempted to defend himself from the charges, Valentinian drew his sword and together with Heraclius, struck Aëtius on the head, killing him.

Later, when Valentinian boasted that he had done well in disposing of Aëtius, someone at court responded, "Whether well or not, I do not know.

But know that you have cut off your right hand with your left."

Edward Gibbon credits Sidonius Apollinaris with this famous observation.

Heraclius’s alliance with Petronius ends, however, with the death of Aëtius: when Maximus asks to be conferred the consulship and the patriciate, Heraclius advises Valentinian to refuse.

Heraclius, in fact, has advised the Emperor not to allow anyone to possess the power that Aëtius had wielded.

The Maltese Islands had become a thriving part of the Roman Empire by 117, being promoted to the status of municipium under Hadrian.

When the Roman Empire split into Eastern and Western divisions in the fourth century, Malta had fallen under the control of the Greek-speaking Eastern Roman (Byzantine) Empire from 395,which rules from Constantinople.

Although Malta will be under Byzantine rule for four centuries, not much is known from this period.

There is evidence that Germanic tribes, including the Goths and, in 354, the Vandals, briefly took control of the islands before the Empire launched a counterattack and retook Malta.

Maximus, according to John of Antioch, was so irritated by Valentinian’s refusal to appoint him as his magister militum that he decided to have Valentinian assassinated as well.

He chooses as accomplices Optilia and Thraustila, two Scythians who had fought under the command of Aetius and who, after the death of their general, had been appointed as Valentinian’s escort.

Maximus easily persuades them that Valentinian was the only one responsible for the death of Aetius, and that the two soldiers must avenge their old commander, while at the same time also promising them a reward for the betrayal of the Emperor.

Valentinian, who is in Rome, goes on March 16, 455, to Campus Martius with some guards, accompanied by Optilia, Thraustila and their men.

As soon as the Emperor dismounts to practice with the bow, Optilia comes up with his men and hits him in the temple.

As Valentinian turns to look at his attackers, Optilia kills him.

Thraustila at the same moment kills Heraclius.

Most of the soldiers standing close by had been faithful followers of Aetius and none lift a hand to save the emperor.

The two Scythians take the imperial diadem and robe and bring them to Maximus.

The sudden and violent death of Valentinian III leaves the Western Roman Empire without an obvious successor to the throne, with several candidates supported by various groups of the imperial bureaucracy and the military.

In particular, the army’s support is split between three main candidates: Maximianus, the former domesticus ("bodyguard") of Aëtius, who is the son of an Egyptian merchant named Domninus who had become rich in Italy; the future emperor Majorian, who commands the army after the death of Aetius and who has the backing of the Empress Licinia Eudoxia; and Maximus himself, who has the support of the Roman Senate and who in the end, on March 17, defeats his rivals and secures the throne by distributing money to officials of the imperial palace.

After gaining control of the palace, Maximus consolidates his hold on power by immediately marrying Licinia Eudoxia, the widow of Valentinian III.

She only marries him reluctantly, suspecting that in fact he had been involved in the murder of her late husband; and indeed Maximus treats Valentinian III's assassins with considerable favor.

The eastern court at Constantinople has refused to recognize Maximus’s accession, so to further secure his position, Maximus quickly recalls Avitus, appoints him as Master of Soldiers, and sends him on a mission to Toulouse to the court of Theodoric II, who had succeeded to his father, at Toulouse.

This embassy probably confirmed to the new king and his people the condition of foederati of the Empire and asked for their support for the new Emperor.

Maximus also proceeds to cancel the betrothal of Licinia’s daughter, Eudocia, to Huneric, the son of the Vandal king Genseric.

This infuriates the Vandal king, who only needs the excuse of Licinia’s despairing appeal to the Vandal court for help to begin preparations for the invasion of Italy.

The city of Vindobona (Vienna) is struck by an epidemic that spreads through the Roman provinces.

The disease is probably streptococcus or a form of scarlet fever with streptococcus pneumoniae (approximate date).

Genseric, responding to an appeal by Eudoxia for help against the usurping Maximus, sails with the Vandal fleet to the mouth of the Tiber River in May 455 and advances on Rome.

Panic grips the city of Rome as  the news of the Vandal landing spreads, and many of its inhabitants take to flight.

The Emperor, aware that Avitus has not yet returned with the expected Visigothic aid, decides that it is fruitless to mount a defense against the Vandals, so he attempts to organize his escape, urging the Senate to accompany him.

However, in the panic, Petronius Maximus is completely abandoned by his bodyguard and entourage and left to fend for himself.

As Maximus rides out of the city on his own on May 31, 455, he is set upon by an angry mob, which stones him to death. (Another account has it that he was killed by "a certain Roman soldier named Ursus".)

He had reigned for only seventy-eight days.

His body is mutilated and flung into the Tiber.

His son from his first marriage, Palladius, who has held the title of Caesar between March 17 and May 31, and who has married his stepsister Eudocia, is probably executed.

King Genseric leads the Vandals into Rome after he has promised Pope Leo I not to burn and plunder the city.

The Vandals occupy the city for a fortnight, systematically plundering the temple on Capitoline Hill and other symbols of Roman power, including whatever the Visigoths might have left of such troves as the Second Temple treasure.

Eudoxia and her daughters, Eudocia and Placidia, are taken hostage.

The loot is send to the harbor of Ostia and loaded into ships, whence the Vandals depart and return to Carthage.