Cassius’s iron grip on his troops was legendary, and it made him indispensable to Rome. Marcus and Cassius had long been family friends, although Cassius was rumored to criticize the emperor behind his back. Marcus would tell his courtiers, “It is impossible to make men exactly as one would wish them to be; we must use them such as they are.” His reputation for clemency and forgiveness stood in total contrast to Cassius’s severity. Nevertheless, despite their opposing characters, Marcus placed his trust in Cassius as a general. During the Parthian War, while Lucius Verus indulged his vices at a safe distance from any actual fighting, Cassius achieved one stunning victory after another, relentlessly pursuing King Vologases deep into Parthian territory. He quickly rose to become Lucius’s second in command. Near the end of the war, however, he allowed his men to sack the twin cities of Ctesiphon and Seleucia, on the River Tigris, where, it was claimed, they contracted the plague. The returning troops brought it home to their legionary bases throughout the provinces, and from there it ravaged the empire. Cassius was rewarded, however, for driving the Parthians out of Syria by being appointed imperial legate (a governor with supreme command) of the province, answerable directly to the emperors. A few years later, in 169 AD, the Emperor Lucius’s untimely demise left a power vacuum waiting to be filled.
In 172 AD, while Marcus was occupied with the First Marcomannic War, on the northern frontier, a tribe called the Bucoli, or “Herdsmen,” who came from the northwest region of the Nile Delta near Alexandria, instigated a revolt against the Roman authorities. This was a major emergency requiring Cassius to enter Egypt with his two Syrian legions, which meant he had to be granted imperium, supreme military authority equal to that of the emperor in his absence. Native Egyptians had borne the brunt of tax increases required to fund Marcus’s war in the north. As a result, more and more of them had turned to banditry, and eventually, out of desperation, they formed a rebel army, led by a charismatic young warrior-priest called Isidorus. The story goes that a handful of these men disguised themselves in women’s clothing and approached a Roman centurion, pretending that they were going to pay him a ransom of gold for their captured husbands. They ambushed him, however, and then captured and sacrificed another officer, reputedly swearing an oath over his bloody entrails before ritually devouring them. News of this reputed act of terrorism quickly spread across Egypt, and a general uprising ensued.
The Bucoli rapidly gained enough support from other tribes to surround and attack Alexandria. When the Egyptian legion confronted the tribesmen in a pitched battle, the vastly outnumbered Romans suffered a humiliating defeat. The Bucoli and their allies continued to besiege Alexandria for months while plague and famine devastated the city. They would have sacked Alexandria had Cassius and his troops not been sent from Syria to relieve the Alexandrian garrison and put down the uprising. He faced so many tribal warriors, though, that he dared not launch a direct counterattack even with three legions under his command. Instead, he chose to bide his time, sowing dissent and instigating quarrels among the enemy tribes until he was finally able to divide and conquer them. Cassius’s reward was to retain imperium throughout the eastern provinces, granting him a unique status and set of powers, dangerously close to those of an emperor.
At the age of forty-five, Cassius had become a hero to his countrymen as a result of his dramatic military victories. His authority was further enhanced by his noble lineage: his mother, Julia Cassia Alexandra, was one of the Cassii, an ancient Roman family famous for their old-fashioned toughness. She was a princess, descended on her father’s side from King Herod the Great of Judea and on her mother’s from Augustus, the first Roman emperor. She also claimed descent from another Roman client-king, Antiochus IV Epiphanes of Commagene, making Cassius a member of the Seleucid imperial dynasty.
In short, Cassius was born to rule. Given his noble pedigree and celebrated military victories, he doubtless viewed himself as a natural successor to the Emperor Lucius Verus. However, far to the north, Marcus had promoted Claudius Pompeianus, another Syrian general, and one from much humbler stock. Pompeianus had already distinguished himself during the Parthian War and subsequently married Marcus’s daughter Lucilla, the widow of Lucius Verus. He served as the most senior general on the northern frontier during the Marcomannic Wars and became the emperor’s right-hand man. It was even rumored that Marcus had invited Pompeianus to become Caesar, although for some reason he declined. It seems likely that Cassius found the idea intolerable that a commoner from his own country might be promoted above him.
Cassius has steadily climbed the ladder of power since the day the Emperor Lucius died. Now, in 175 AD, Cassius has been holding the authority of an emperor in the east for three years; he has one rung left to climb, and Marcus Aurelius is the only person standing in his way. The single word he holds in his hands, emanes, comes from Herodes Atticus, the Sophist who tutored Marcus in Greek rhetoric as a youth. Herodes was known for his eloquence in delivering elaborate speeches, but this letter had the sort of laconic punch more typical of Stoics than Sophists. Only one word was necessary to make his point. Driven by his lust for absolute power, Cassius has rashly instigated a civil war that threatens to tear the whole empire apart and engulf the lives of millions in bloodshed.
At the far side of the empire, over fifteen hundred miles away, an exhausted dispatch rider arrives at the army camp at Sirmium, the capital of Lower Pannonia (in modern-day Serbia). The soldiers who meet him rush him straight to the emperor’s residence in the middle of the camp. It has taken over ten days, using the emergency relay system, to get the news from the east via Rome to the northern frontier. He hesitates before speaking. His news is so astonishing that he can scarcely believe it himself: “My lord Caesar, General Avidius Cassius has betrayed you … the Egyptian legion have acclaimed him emperor!”
The courier has with him a letter from the Senate confirming the news: on May 3, 175 AD, Avidius Cassius had been acclaimed emperor of Rome by the Egyptian legion in Alexandria. “My lord, they’re telling everyone that you’re dead,” the messenger explains. The news came from Publius Martius Verus, governor of the Roman province of Cappadocia (in modern-day Turkey). He had served with great distinction as a general along with Cassius and Pompeianus in the Parthian War. Crucially, Martius Verus’s alarming news comes with the reassurance that he and the three legions under his command have declared their unwavering loyalty to Marcus. However, Cassius reputedly has garnered support for his rebellion throughout the region lying south of the Taurus mountain range, roughly half the eastern empire. A number of senators at Rome who had opposed the Marcomannic campaign have seized the opportunity to petition in favor of Cassius. So far, though, the Senate as a whole remains loyal to Marcus. Nevertheless, Cassius is a highly accomplished general with seven legions under his command. He also controls Egypt, the breadbasket of the empire and by far the wealthiest province in the east. Its capital, Alexandria, is the second largest city and has the largest port in the empire. If exports from Egypt are cut off, Rome will eventually run out of bread, leading to rioting and looting. The fate of the empire therefore hangs in the balance.