Marcus' eleven-year-old daughter, Annia Lucilla, is betrothed…

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.

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.

The Parthians, under Vologases IV, have invaded Armenia, deposed its Roman client king in favor of a son of Vologases, and destroyed the Roman legion sent to redress the situation.

There is threat of war on Rome’s other frontiers as well—in Britain, and in Raetia and Upper Germany, where the Chatti of the Taunus mountains have recently crossed over the limes.

Marcus Aurelius is unprepared.

Pius seems to have given him no military experience; the biographer writes that Marcus spent the whole of Pius' twenty-three-year reign at the emperor's side—and not in the provinces, where most previous emperors had spent their early careers.

Marcus makes the necessary appointments: Marcus Statius Priscus, the governor of Britain, is sent to replace the late Severianus as governor of Cappadocia, and is in turn replaced by Sextus Calpurnius Agricola.

More bad news arrives: Attidius Cornelianus' army had been defeated in battle against the Parthians, and retreated in disarray.

Reinforcements are dispatched for the Parthian frontier.

P. Julius Geminius Marcianus, an African senator commanding X Gemina at Vindobona (Vienna), leaves for Cappadocia with vexillations from the Danubian legions.

Three full legions are also sent east: I Minervia from Bonn in Upper Germany, II Adiutrix from Aquincum, and V Macedonica from Troesmis.

The northern frontiers are strategically weakened; frontier governors are told to avoid conflict wherever possible.

Attidius Cornelianus himself is replaced by M. Annius Libo, Marcus' first cousin.

He is young—his first consulship is in 161, so he is probably in his early thirties—and, as a mere patrician, lacks military experience.

Marcus has chosen a reliable man rather than a talented one.

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.