The Parthians, under Vologases IV, have invaded…

Emperor Huan, apparently in reaction to spending due to renewed Qiang rebellions and new agrarian revolts, issues an edict in 161, offering minor offices for sale—including imperial guard officer positions.

(A bad precedent, thus established, this practice will become even more prevalent and problematic under Huan's successor, Emperor Ling.)

While Huan actually appears to have a knack for finding good generals to suppress the rebellions or to persuade the rebels to surrender, the rampant corruption will cause new rebellions as soon as the old ones are quelled.

Parthian king Vologases IV enters the Kingdom of Armenia (a Roman client state) in the late summer autumn of 161, expels its king and installs his own—Pacorus, an Arsacid like himself.

At the time of the invasion, the governor of Syria is L. Attidius Cornelianus, who had been retained as governor even though his term ended in 161, presumably to avoid giving the Parthians the chance to wrong-foot his replacement.

The governor of Cappadocia, the front-line in all Armenian conflicts, is Marcus Sedatius Severianus, a Gaul with much experience in military matters.

Persuaded by Alexander of Abonutichus, a prophet who carries a snake named Glycon around with him, that he can defeat the Parthians easily, and win glory for himself, Severianus leads a legion (perhaps the IX Hispana) into Armenia, but is trapped by the great Parthian general Chosrhoes at Elegia, a town just beyond the Cappadocian frontiers, high up past the headwaters of the Euphrates.

Severianus makes some attempt to fight Chosrhoes, but soon realizes the futility of his campaign, and commits suicide.

His legion is massacred.

The campaign had only lasted three days.

Marcus, now effectively sole ruler of the Empire, makes some show of resistance: the biographer writes that he was "compelled" to take imperial power.

This may have been a genuine horror imperii, "fear of imperial power".

With his preference for the philosophic life, Marcus finds the imperial office unappealing.

His training as a Stoic, however, has made the choice clear: it is his duty.

Although Marcus shows no personal affection for Hadrian (significantly, he does not thank him in the first book of his Meditations), he presumably believes it his duty to enact the man's succession plans.

Thus, although the senate plans to confirm Marcus alone, he refuses to take office unless Lucius receives equal powers, despite the fact that Verus is obviously less competent to rule.

The senate accepts, granting Lucius the imperium, the tribunician power, and the name Augustus.

He is soon formally elected as Pontifex Maximus, chief priest of the official cults.

Marcus becomes, in official titulature, Imperator Caesar Marcus Aurelius Antoninus Augustus; Lucius, forgoing his name Commodus and taking Marcus' family name, Verus, becomes Imperator Caesar Lucius Aurelius Verus Augustus.

It is the first time that Rome is ruled by two emperors.

In spite of their nominal equality, Marcus holds more auctoritas, or "authority", than Lucius.

He has been consul once more than Lucius, he had shared in Pius' administration, and he alone is Pontifex Maximus.

It would have been clear to the public which emperor was the more senior.

Immediately after their senate confirmation, the emperors proceed to the Castra Praetoria, the camp of the praetorian guard.

Lucius addresses the assembled troops, which then acclaim the pair as imperatores.

Then, like every new emperor since Claudius, Lucius promises the troops a special donative.

This donative, however, is twice the size of those past: twenty thousand sesterces (five thousand denarii) per capita, with more to officers.

In return for this bounty, equivalent to several years' pay, the troops swear an oath to protect the emperors.

The ceremony is perhaps not entirely necessary, given that Marcus' accession had been peaceful and unopposed, but it is good insurance against later military troubles.

Upon his accession he also devalues the Roman currency, decreasing the silver purity of the denarius from 83.5% to 79%—the silver weight dropping from 2.68 grams to 2.57 grams.

However, Marcus will later revisit the issue of currency reform.

If Pius' funeral followed the pattern of past funerals, his body would have been incinerated on a pyre at the Campus Martius, while his spirit would rise to the gods' home in the heavens.

Marcus and Lucius nominate their father for deification.

In contrast to their behavior during Pius' campaign to deify Hadrian, the senate does not oppose the emperors' wishes.

A flamen, or cultic priest, is appointed to minister the cult of the deified Pius, now Divus Antoninus.

Pius' remains are laid to rest in the Hadrian's mausoleum, beside the remains of Marcus' children and of Hadrian himself.

The temple he had dedicated to his wife, Diva Faustina, becomes the Temple of Antoninus and Faustina; it survives as the church of San Lorenzo in Miranda.

Antoninus Pius has never once left Italy during his relatively peaceable twenty-three year reign.

In 160, Marcus Aurelius and Lucius Verus had been designated joint consuls for the following year.

Perhaps Pius was already ill; in any case, he dies before the year is out.

On his deathbed, Pius speaks of nothing but the state and the foreign kings who had wronged him.

One of those kings, Vologases IV of Parthia, will make his move in late summer or early autumn of this year.

Two days before Pius’s death, he is at his ancestral estate in Lorium.

He eats Alpine cheese at dinner quite greedily.

In the night he vomits; he has a fever the next day.

The day after that, March 7, 161, he summons the imperial council, and passes the state and his daughter to Marcus.

He orders that the golden statue of Fortune, which had been in the bedroom of the emperors, should go to Marcus' bedroom.

Pius turns over, as if going to sleep, and dies.

Marcus' eleven-year-old daughter, Annia Lucilla, is betrothed to Lucius (in spite of the fact that he is, formally, her uncle) soon after the emperors' accession.

At the ceremonies commemorating the event, new provisions are made for the support of poor children, along the lines of earlier imperial foundations.

Marcus and Lucius prove popular with the people of Rome, who strongly approve of their civiliter ("lacking pomp") behavior.

The emperors permit free speech, evinced by the fact that the comedy writer Marullus is able to criticize them without suffering retribution.

At any other time, under any other emperor, he would have been executed.

But it is a peaceful time, a forgiving time.

Marcus replaces a number of the empire's major officials.

The ab epistulis Sextus Caecilius Crescens Volusianus, in charge of the imperial correspondence, is replaced with Titus Varius Clemens.

Clemens is from the frontier province of Pannonia and had served in the war in Mauretania.

Recently, he had served as procurator of five provinces.

He is a man suited for a time of military crisis.

Lucius Volusius Maecianus, Marcus' former tutor, had been prefectural governor of Egypt at Marcus' accession.

Maecianus is recalled, made senator, and appointed prefect of the treasury (aerarium Saturni).

He is made consul soon after.

Fronto's son-in-law, Aufidius Victorinus, is appointed governor of Upper Germany.

Fronto had returned to his Roman townhouse at dawn on March 28, having left his home in Cirta as soon as news of his pupils' accession reached him.

He sent a note to the imperial freedman Charilas, asking if he could call on the emperors.

Fronto would later explain that he had not dared to write the emperors directly.

The tutor is immensely proud of his students.

Reflecting on the speech he had written on taking his consulship in 143, when he had praised the young Marcus, Fronto is ebullient.

Fronto calls on Marcus alone; neither think to invite Lucius.

Lucius is less esteemed by his tutor than his brother, as his interests are on a lower level.

Lucius asks Fronto to adjudicate in a dispute he and his friend Calpurnius are having on the relative merits of two actors.

Marcus tells Fronto of his reading—Coelius and a little Cicero—and his family.

His daughters are in Rome, with their great-great-aunt Matidia; Marcus thinks the evening air of the country is too cold for them.

Pius' fortune passes on to Faustina the Younger in accordance with his will. (Marcus has little need of his wife's fortune. Indeed, at his accession, Marcus transfers part of his mother's estate to his nephew, Ummius Quadratus.)

Faustina is three months pregnant at her husband's accession.

During the pregnancy she dreams of giving birth to two serpents, one fiercer than the other.

On August 31, she gives birth at Lanuvium to twins: T. Aurelius Fulvus Antoninus and Lucius Aurelius Commodus.

Aside from the fact that the twins share Caligula's birthday, the omens are favorable, and the astrologers draw positive horoscopes for the children.

The births are celebrated on the imperial coinage.

Marcus' early reign proceeds smoothly.

He is able to give himself wholly to philosophy and the pursuit of popular affection.

Soon, however, Marcus will find he has many anxieties.

It will mean the end of the felicitas temporum ("happy times") that the coinage of 161 so glibly proclaims.

Marcus takes a four-day public holiday at Alsium, a resort town on the Etrurian coast.

He is too anxious to relax.

Writing to his former tutor Marcus Cornelius Fronto, he declares that he will not speak about his holiday.

Fronto encourages Marcus to rest, calling on the example of his predecessors (Pius had enjoyed exercise in the palaestra, fishing, and comedy), going so far as to write up a fable about the gods' division of the day between morning and evening—Marcus had apparently been spending most of his evenings on judicial matters instead of leisure.

Marcus cannot take Fronto's advice.

Fronto sends Marcus a selection of reading material, including Cicero's pro lege Manilia, in which the orator had argued in favor of Pompey taking supreme command in the Mithridatic War.

It is an apt reference (Pompey's war had taken him to Armenia), and may have had some impact on the decision to send Lucius to the eastern front.

To settle his unease over the course of the Parthian war, Fronto writes Marcus a long and considered letter, full of historical references.

In modern editions of Fronto's works, it is labeled De bello Parthico (On the Parthian War).

There had been reverses in Rome's past, Fronto writes, at Allia, at Caudium, at Cannae, at Numantia, Cirta, and Carrhae; under Trajan, Hadrian, and Pius; but, in the end, Romans had always prevailed over their enemies.

The Romans repulse the Chatti and Chauci in their three-year invasion of the provinces of Raetia and Germania Superior, beginning in 162 and continuing until 165.

The Tiber floods over its banks in the spring of 162, destroying much of Rome, drowning many animals, and leaving the city in famine.

Marcus and Lucius give the crisis their personal attention.

In other times of famine, the emperors are said to have provided for the Italian communities out of the Roman granaries.

Fronto's letters continue through Marcus' early reign.

Fronto feels that, because of Marcus' prominence and public duties, lessons are more important now than they had ever been before.

Fronto again reminds his pupil of the tension between his role and his philosophic pretensions.

The early days of Marcus' reign are the happiest of Fronto's life: his pupil is beloved by the people of Rome, an excellent emperor, a fond pupil, and, perhaps most importantly, as eloquent as could be wished.

Marcus had displayed rhetorical skill in his speech to the senate after an earthquake at Cyzicus.

It had conveyed the drama of the disaster, and the senate had been awed.

Fronto is hugely pleased.

Over the winter of 161–62, as more bad news arrives—a rebellion is brewing in Syria—it is decided that Lucius should direct the Parthian war in person.

He is stronger and healthier than Marcus, the argument goes, more suited to military activity.

Lucius' biographer suggests ulterior motives: to restrain Lucius' debaucheries, to make him thrifty, to reform his morals by the terror of war, to realize that he was an emperor.

Whatever the case, the senate gives its assent, and Lucius leaves.

Marcus will remain in Rome.

Furius Victorinus, one of the two praetorian prefects, is sent with Lucius, as are a pair of senators, M. Pontius Laelianus Larcius Sabinus and M. Iallius Bassus, and part of the Praetorian Guard.

Victorinus had previously served as procurator of Galatia, giving him some experience with eastern affairs.

Moreover, he is far more qualified than his praetorian partner, Cornelius Repentinus, who is said to owe his office to the influence of Pius' mistress Galeria Lysistrate.

Repentius has the rank of a senator, but no real access to senatorial circles—his is merely a decorative title.

Since a prefect has to accompany the Guard, Victorinus is the clear choice.

Laelianus had been governor of both Pannonias and governor of Syria in 153; hence he has firsthand knowledge of the eastern army and military strategy on the frontiers.

He is made comes Augustorum ("companion of the emperors") for his service.

Laelianus is, in the words of Fronto, "a serious man and an old-fashioned disciplinarian".

Bassus had been governor of Lower Moesia, and is also made comes.Lucius selects his favorite freedmen, including Geminus, Agaclytus, Coedes, Eclectus, and Nicomedes, who gives up his duties as praefectus vehiculorum to run the commissariat of the expeditionary force.

The fleet of Misenum is charged with transporting the emperor and general communications and transport.

Lucius leaves in the summer of 162 to take a ship from Brundisium; Marcus follows him as far as Capua.

Lucius feasts himself in the country houses along his route, and hunts at Apulia.

He falls ill at Canosa, probably afflicted with a mild stroke, and takes to bed.

Marcus makes prayers to the gods for his safety in front of the senate, and hurries south to see him.

Fronto is upset at the news, but is reassured when Lucius sends him a letter describing his treatment and recovery.

In his reply, Fronto urges his pupil to moderate his desires, and recommends a few days of quiet bedrest.

Lucius is better after three days' fasting and a bloodletting.

It was probably only a mild stroke.