3rd c. CE

Rome fell once again into chaos, with the Praetorians literally auctioning the Empire to the highest bidder, a senator named Didius Julianus.  Unbeknownst to Rome, the legions of the Danubian provinces had already cast their vote in favor of Lucius Septimius Severus, a career soldier and governor of Pannonia Superior.  Severus led his army south to Rome as the Praetorians holed up inside their camp, but through a ruse the crafty general lured the Guard out, unarmed.  Thereafter Julianus was eliminated and the captured Praetorians replaced with loyal soldiers of the Severan legions, a tactic Vitellius had attempted with short-lived success in 69 CE.

Although Severus had to contend with his strong-willed new Prefect, Plautianus, he busied the Praetorians with new campaigns and conflicts, until the Emperor’s death in 211 CE.  But Severus’ heirs Geta and Caracalla, like many other Emperors' offspring, were not equal to their father in capability.  Shortly after their joint rule began, the jealous Caracalla murdered his brother, creating dissension among the legions and Praetorians alike.<br>After such an ill-omened start to his reign, Caracalla could never regain the trust of his soldiers, despite his overeager efforts to gain their love by living among them as a common soldier.  In 217 CE, while on campaign with Caracalla in the East, the Praetorian Prefect Macrinus assassinated the would-be “soldier Emperor” and amazingly, took Caracalla’s place as Emperor.

But Macrinus’ reign would last only a year before he fell to another contender, the bizarre Elagabalus, whose great-aunt was Julia Domna, powerfully influential wife of Septimius Severus.  Elagabalus, priest of the eastern cult of Elagabal, proved too unmilitary and un-Roman for the Praetorians to accept.  In 222 CE, they replaced the priest-Emperor with his pubescent cousin, Severus Alexander, who of course could not control the avaricious willfulness of the Guard.  Since he did nothing to curb their excesses, the Praetorians tolerated Alexander until 235, when he too was replaced.

From this period to the Guard’s ultimate end in the civil war of 305 CE which brought Constantine the Great to the imperial throne, the Praetorians grew ever more mercenary and unbiddable.  Under capable Emperors such as Aurelian and Diocletian, the Guard proved useful in the field.  However, for most Emperors of the time - and for the people of Rome - the Praetorian Guard was a menacing presence in their walled camp on the outskirts of Rome, always watchful, always dangerous.

Demise of the Praetorians

The Praetorian Guard, ever since its consolidation at Rome in 23 CE on the orders of Emperor Tiberius, had occupied a position of direct military power over the city and her inhabitants.  Accountable not to the Senate or the citizenry of Rome, but only to the Emperor to whom they swore (fickle) allegiance, the Praetorians exploited their military presence to oppress, murder, and intimidate the Roman people for centuries.

When a strong Emperor could keep his Praetorians busy at campaigning, he stood a chance of controlling their baser tendencies.  But the danger in disciplining the Guard made the effort very much like attempting to ride a tiger – apply any controlling pressure to the beast, and he might devour his rider.  Fearing for life, many a weak ruler neglected to exercise command over the Praetorians, and Rome suffered their predations.

The underlying problem of the Guard’s corruption lay in the loyalty oath that all Roman soldiers swore.  Under the Republic, new soldiers promised to serve Rome, but under the Empire, soldiers gave their allegiance not to Rome, but to one man, their Emperor.  As Rome’s succession problems gave rise to outright civil war, Emperors were made and deposed too easily, weakening the legitimacy of the office and its hereditary nature.  Once the Guard discovered their latent power to effect a coup d'etat at will, it was far easier to abandon a promise to a fragile, mortal man than one made to the deathless idea of Rome the state.

But the Guard’s sphere of influence was limited to the city of Rome and to the Emperor, when he was in the city.  Those Emperors who survived longest and ruled most effectively did so because they commanded the loyalty of the frontier legions, who trumped the Praetorians by superior numbers and better combat experience.  It was this vulnerability that spelled the ultimate demise of the Praetorian Guard.

In 305 CE, at the height of the Tetrarchy, the senior Emperors Diocletian and Maximian achieved a rare feat: they retired.  In keeping with the rules of Tetrarchic succession, they promoted the junior Emperors Galerius and Constantius as replacements.  But the next year, Constantius died unexpectedly while on a tour of Britannia, and his loyal legions there impetuously proclaimed his son, Constantine, as the new co-Emperor.  The Praetorians had their own contestant: Maximian’s son Maxentius, who ruled in Rome from 306-312 CE.  An inveterate Christian-hater - or so Constantine’s apologists claimed - Maxentius is said to have turned a blind eye as his Guardsmen mercilessly hunted down the adherents of Christ.

For six years of his rival’s rule in Rome, Constantine held his army in check as he waited to see if Maxentius’ other enemies would finish him off.  After an army led by Maxentius’ Praetorian Prefect Pompeianus crushed the usurper Domitius Alexander, Constantine decided to wait no longer.  He led his legions south to face the inevitable clash with the Emperor's forces.  In 312 CE, Constantine entered Italia, where he brushed aside a challenge by the Prefect Pompeianus.

Now left with no other option, Maxentius prepared to defend Rome.  He chose the ground north of the Tiber River, outside of the city, and arrayed his forces there to await Constantine’s approach.  To facilitate the movement of his forces and supplies, Maxentius ordered the construction of a pontoon bridge to supplement the stone Milvian Bridge that crossed the Tiber about 3 kilometers north of Rome.  It was a fateful order.

As his army marched toward Rome, Constantine experienced a hallucinatory vision in which the Christian god promised him victory under the sign of Christ, the Greek letters chi-rho.  Announcing this to his troops as an omen of coming victory, Constantine unfurled a great chi-rho banner with the Latin pronouncement, - By this sign you will conquer.-

Perhaps the vision was a ploy by Constantine to rally his tired troops, many of whom were devotees of Christianity, or had at least heard of the phenomenon.  Perhaps it was even a genuine experience, although the depth of Constantine’s later adherence to Christian teachings seems to have been superficial and his protestations of faith politically motivated.  Whatever the case, it was a turning point in Roman history.  Inspired by the vision, the banner of Christ, and the promise of victory, Constantine’s army marched with new vigor and purpose – not only to install their general as ruler of the Roman world, but to topple old gods in the name of the new.

When the armies collided, Constantine’s vision proved true.  His motivated troops routed the forces of Maxentius, including the Praetorian Guard who took the field with him.  Retreating in good order but still engaged by the pursuing enemy, the beaten Praetorians fell back to the Milvian Bridge.  As the Praetorians and Maxentius attempted to cross the wooden pontoon bridge, it collapsed under the weight of hundreds of armored bodies.  Flung into the Tiber, many Praetorians drowned, their Emperor and an entire era dying with them.

Constantine, upon learning of Maxentius’ end, mopped up the remaining resistance and moved into Rome to receive the imperial laurel.  He disbanded the Praetorian Guard as punishment for their support of his enemy.  He also ordered the demolishment of the western wall of the Castra Praetoria, the fortress headquarters of the Guard since the days of Tiberius.  The protective duties formerly associated with the Praetorians were assumed by Constantine’s bodyguard corps, the Scholae Palatinae.  The office of Praetorian Prefect remained; devoid of its command but retaining the title’s prestige, it became the highest civilian post in the Empire.

As for the Praetorian Guard, they were but a memory, unmissed and unmourned.  Only a caricatured legacy of corruption survived to characterize their effect on the history of Rome.