How did the Antonine Plague set the stage for the Marcomannic Wars?
By crippling Rome’s manpower and finances just as Germanic and Sarmatian groups crossed the Danube, the Antonine Plague turned a frontier breach into a protracted war. Contemporary writers record depleted legions, delays at the capital, and emergency sales of imperial treasures—conditions that framed the Marcomannic Wars from 166.
The Antonine Plague, carried west by troops returning from Lucius Verus’ Parthian campaign (165–166), hit Rome by 166 and ravaged forces assembling at Aquileia in 168/69. As the epidemic surged, Germanic and Sarmatian groups pressed over the Danube, and Rome’s initial response was slowed by religious expiations and the sheer scale of mortality. With garrisons and recruits thinned, Marcus Aurelius resorted to continuous levies and liquidated imperial plate and gems to fund years of campaigning. Ancient observers underscore the crisis: some days, thousands reportedly died in Rome. The result was a grinding Danubian struggle—recall the Quadi “rain miracle”—fought under epidemic constraints throughout Marcus’ reign.
Key Factors
Manpower shock and emergency levies
The plague tore through garrisons and marching columns just as Danubian crossings began, leaving units understrength. Orosius says the legions were so depleted the war could not proceed without new levies, prompting Marcus to recruit continuously at Carnuntum for three years.
Operational delay and crisis atmosphere
Mass mortality in the capital triggered expiations and delayed the emperor’s departure for the front. The Historia Augusta evokes bodies hauled by cart and a city gripped by dread as war loomed amid pestilence.
Fiscal strain and monetization of the court
Falling revenues and surging military costs forced extraordinary measures. Eutropius reports Marcus sold imperial plate, garments, and gems for two months in the Forum of Trajan to finance the German war—evidence of prolonged campaigning under epidemic attrition.
Sick frontier and escalated Danubian pressure
Galen’s presence with the army at Aquileia during an outbreak shows the disease struck staging grounds on the Ister itself. With Pannonian and Italian forces weakened—and mobile tribes also under stress—incursions swelled into a long war rather than a brief punitive campaign.
Historical Evidence
"“Such a pestilence [in Rome] that the dead were removed in carts and wagons,” alongside a seven‑day lectisternium before Marcus set out."
"Galen describes patients who by the ninth day were covered with pustules, one coughing up scabs from the throat and lungs."
"To meet war costs, Marcus sold imperial plate, garments, and gems for two months in the Forum of Trajan."
"Legions were so depleted by plague that the Marcomannic War “could not be carried on without a new levy,” held at Carnuntum “continuously for three years.”"
Part of Marcomannic Wars Begin
This entry explains why plague and invasion coincided in 166, shaping the Marcomannic Wars’ long, defensive character. For campaigns, commanders, and episodes like the Quadi “rain miracle,” see the Marcomannic Wars Begin (166) and related Roman Germanic Wars pages.
More Questions About Marcomannic Wars Begin
Why did the Marcomannic Wars begin in 166 CE?
A Danube crossing by 6,000 Langobardi and Obii in late 166 CE triggered the Marcomannic Wars. Repulsed by Roman detachments, the raid snowballed into a wider Marcomanni–Quadi–Sarmatian coalition just as Rome’s frontier was weakened by troop redeployments from the Parthian War and the onset of the Antonine Plague.
Marcus Aurelius on the Danube: the opening campaigns, 166–168
In late 166 CE, a Langobardi–Obii raid across the Danube was crushed by Roman forces, prompting envoys led by Ballomar to sue for peace. In 168, Marcus Aurelius and Lucius Verus advanced to Aquileia, raising emergency levies amid the Antonine plague to prepare for a protracted Germanic and Marcomannic war.
Marcomanni, Quadi, and Iazyges: Rome’s opponents at the outbreak
The Marcomannic Wars opened in 166–167 with the Marcomanni under King Ballomarius (Ballomar), the Quadi, and the Sarmatian Iazyges launching Danube incursions. Allied groups like the Langobardi and Obii joined, but early crossings were repelled by Roman commanders Vindex and Candidus before Ballomarius led a peace embassy to the Pannonian governor M. Iallius Bassus.
Winter warfare on the Danube: crossings and fortified camps in 166–168
Between 166 and 168 CE, Rome fought a winter defensive war on the mid-Danube, repelling small crossings and consolidating fortified winter quarters at Carnuntum. Marcus Aurelius used Pannonia as his base, restricted frontier markets, and in 168 with Lucius Verus secured Italy and Illyricum—stabilizing the line before later river offensives.
Sources
- [1] Historia Augusta, Life of Marcus Aurelius (Part 1)
- [2] Historia Augusta, Life of Lucius Verus
- [3] Cassius Dio, Roman History, Epitome of Book 72
- [4] Cassius Dio, Roman History, Epitome of Book 73
- [5] Cassius Dio on the “Rain Miracle” (Livius, Cary trans.)
- [6] Eutropius, Breviarium 8.13
- [7] Paulus Orosius, Histories against the Pagans 7 (A) (Raymond trans.)
- [8] Galen, Methodus medendi 5.12 (quoted passages)
- [9] R. P. Duncan-Jones, “The impact of the Antonine plague,” Journal of Roman Archaeology 9 (1996)