Antonine Plague (AD 165-180): The Epidemic That Shook Rome

The Antonine Plague was a pandemic that swept through the Roman Empire from about AD 165, during the reign of Marcus Aurelius. Carried back from the war against Parthia in Mesopotamia, it reached Rome by 166 and spread to Italy, Gaul and the armies on the Rhine and Danube, recurring for some 15 years. It was probably smallpox, killed millions of people, and is regarded as one of the first pandemics in recorded history.

Origins in the Parthian War

In AD 161 the Parthian king Vologases IV attacked Roman positions in Armenia and Syria. Marcus Aurelius sent his co-emperor, Lucius Verus, to the East, where the general Avidius Cassius led a counter-offensive into Mesopotamia. In the winter of AD 165-166 Roman forces captured and sacked Seleucia on the Tigris, a great Greek city near the Parthian capital Ctesiphon.

Roman writers connected the epidemic with this campaign. A story recorded later by Ammianus Marcellinus claimed that soldiers looting a temple of Apollo at Seleucia opened a golden casket and released a pestilential vapour as divine punishment. Whatever its true source, the disease seems to have spread among the troops in the East around 165 and travelled with them as they returned to the West.

Spread across the empire

The army’s homecoming carried the infection along Roman roads and sea routes. It reached Rome in AD 166, the year Verus celebrated his triumph. In 168-169 an outbreak struck troops gathering at Aquileia in north-eastern Italy for war against Germanic peoples on the Danube. Lucius Verus died suddenly early in 169 on the road back to Rome; the cause may have been a stroke, though plague has also been suggested.

Evidence from Egypt, Asia Minor, Greece, Gaul and the Danube provinces shows that the disease touched much of the empire. In 189, under Commodus, a recurrence struck Rome; Cassius Dio, who lived through it, says that 2,000 people often died in the city in a single day. Whether this was the same disease is likely but not certain.

Galen’s description

The physician Galen, from Pergamon, was in Rome when the plague arrived and left the city in 166. Marcus Aurelius summoned him to Aquileia in 168-169, where he saw the disease at first hand. Galen called it “the great plague” and described its signs in scattered passages: fever, thirst, inflammation of the throat, diarrhoea, and on about the ninth day a black rash of pustules over the body, some ulcerated, which dried, scabbed and fell off.

He did not set out a full clinical account, and he was more interested in treatment than in the disease’s course. Even so, his notes are the main reason most scholars identify the plague as smallpox. A classic study by R. J. and M. L. Littman in 1973 made this case, and it remains the majority view, though measles and other infections have been proposed.

The death toll

No ancient source gives a reliable total. Modern estimates rest on scattered evidence and vary widely.

Part of the difficulty is that smallpox behaves differently in a population that has never met it. In such “virgin soil” conditions, mortality among the infected can be very high, perhaps 25-30 per cent, and nearly everyone may be exposed. Once the disease returns repeatedly, it becomes mainly a childhood illness, which may explain why later outbreaks seem to have been less dramatic.

The empire’s population is itself an estimate, often put at around 60-75 million. Evidence used for higher figures includes sharp drops in recorded taxpayers in some Egyptian villages, a gap in dated building inscriptions and brick stamps, and interruptions in coin and quarry records. Critics argue that such patterns may have other causes, so the scale of mortality remains debated.

How people responded

Ancient medicine had no effective treatment. Galen recommended remedies such as special earths and drugs, and much of his advice amounted to supportive care. Many people turned instead to the gods. Marcus Aurelius, according to the Historia Augusta, summoned priests from all quarters, performed foreign as well as Roman purification rites and paid for the funerals of poorer citizens at public expense.

Cities in the Greek East consulted the oracle of Apollo at Claros, near Ephesus. Inscriptions recording its replies, which prescribed sacrifices and statues of Apollo to ward off plague, have been found at several sites, including Hierapolis in Phrygia and Pergamon. Many scholars link these oracles to the epidemic of the 160s. Such evidence shows how communities across the empire sought religious protection from a disease they could not explain.

Effects on Rome

The plague arrived just as Rome faced a major invasion across the Danube, the start of the Marcomannic Wars. The Historia Augusta says Marcus Aurelius recruited enslaved men, gladiators and even bandits into the army to fill gaps, and sold palace treasures to raise money. Many communities saw farms abandoned, and tax revenue fell.

The army was hit especially hard, because soldiers lived crowded together and moved constantly between regions. Military diplomas and inscriptions suggest that whole units had to be rebuilt, and new legions, the Second and Third Italica, were raised around AD 165-166 as Rome prepared for war in the north. Mines, quarries and building projects were disrupted in several provinces.

Writers of the time reflect the fear. The orator Aelius Aristides described surviving a severe illness during the epidemic at Smyrna. The satirist Lucian mocked the prophet Alexander of Abonoteichus for selling a protective verse that people wrote over their doors. Marcus Aurelius himself, in his Meditations, referred to pestilence as less harmful than corruption of the mind. He died in March AD 180 at Vindobona or Sirmium; some historians suspect the plague, but the sources are not explicit.

Legacy

The Antonine Plague is often compared with the Plague of Athens and the later Plague of Justinian. Some historians, notably Kyle Harper, see it as a turning point that ended the long expansion of the Roman population and economy. Others argue that the empire recovered within a generation and that the plague’s long-term effects have been exaggerated.

The epidemic also shows how a connected empire could spread disease rapidly. Armies, merchants and pilgrims moved along the same routes, and smallpox may have reached the Mediterranean from regions further east. Outbreaks in Han China in the same decades are sometimes mentioned, but any link is speculative.

Timeline

• AD 161: Marcus Aurelius and Lucius Verus become co-emperors; war with Parthia begins.
• AD 165-166: Roman troops sack Seleucia on the Tigris; the epidemic appears among the army.
• AD 166: The plague reaches Rome; Galen leaves the city.
• AD 168-169: Outbreak among troops at Aquileia; Lucius Verus dies early in 169.
• AD 166-180: Marcomannic Wars on the Danube frontier.
• AD 180, March: Marcus Aurelius dies on campaign.
• c. AD 189: A recurrence kills up to 2,000 people a day in Rome, according to Cassius Dio.

Why it matters

The Antonine Plague was one of the first well-documented pandemics in a large, connected empire. It tested Rome’s army and finances at a critical moment and remains central to debates about disease and the fortunes of the Roman world.