What Is 168 CE

Overview

168 CE refers to the year 168 in the Common Era, a time of significant upheaval within the Roman Empire. This year occurred during the reign of Emperor Marcus Aurelius, one of the last rulers of the Nerva–Antonine dynasty and a central figure in Stoic philosophy. As the 168th year of the 1st millennium, it fell within the 2nd century and marked a turning point in Roman stability, as external invasions and internal disease began to erode imperial strength.

The year unfolded against the backdrop of the Marcomannic Wars, a series of conflicts between Rome and Germanic and Sarmatian tribes along the Danube frontier. These wars were among the most serious military challenges Rome had faced in over a century, with 168 CE seeing intensified campaigns as Marcus Aurelius sought to secure the northern borders. The emperor had been on campaign since 166, and by 168, he and his co-emperor Lucius Verus returned briefly to Rome before resuming military operations.

Another defining feature of 168 CE was the ongoing Antonine Plague, which had been ravaging the empire since 165. Believed to be smallpox or measles, the plague killed an estimated 5 million people across the empire, with mortality peaking at around 2,000 deaths per day in Rome. This demographic crisis weakened the Roman military and economy, contributing to long-term decline. The year thus symbolizes a shift from the relative peace of the Pax Romana to a more turbulent era of crisis and transformation.

How It Works

Understanding 168 CE requires examining the political, military, and public health systems of the Roman Empire during this period. The year operated under the Julian calendar, which had been in use since 45 BCE and established a 365-day year with a leap day every four years. However, due to administrative inconsistencies, leap years were sometimes miscalculated, and 168 CE was not a leap year in practice. The calendar structured civic and religious life, from consular appointments to festival dates.

• Julian Calendar: The official calendar of Rome, introduced by Julius Caesar, divided the year into 12 months and was used until the Gregorian reform in 1582. In 168 CE, it placed the year as Year 921 Ab Urbe Condita (from the founding of Rome).
• Co-Emperorship: Marcus Aurelius ruled jointly with Lucius Verus, a practice established by Antoninus Pius. This dual leadership aimed to strengthen governance but ended with Verus’s death in early 169 CE.
• Consular System: Each year was named after its two consuls. In 168 CE, the consuls were Lucius Artorius Castus and Tiberius Claudius Julianus, whose names were used in official records.
• Provincial Administration: The empire was divided into provinces governed by appointed officials. In 168 CE, military governors in Pannonia and Germania played key roles in the Marcomannic Wars.
• Plague Response: Roman medical understanding was limited; physicians like Galen documented symptoms but lacked effective treatments. Quarantine and flight were common responses.
• Military Campaigns: The Roman army relied on legions and auxiliaries. In 168 CE, troops were deployed along the Danube to repel invasions by the Marcomanni and Quadi.

Key Details and Comparisons

The comparison above highlights how 168 CE was a pivotal moment between Rome’s golden age and its later decline. Unlike 100 CE, when Trajan expanded the empire to its greatest extent, 168 CE saw Rome on the defensive. The Marcomannic Wars marked the first time since the Teutoburg Forest disaster in 9 CE that Germanic tribes breached the imperial frontier, reaching Aquileia in 168. In contrast to the stability of the early 2nd century, this period saw rising mortality, military strain, and political uncertainty. By 200 CE, the empire would face even greater turmoil, but 168 CE was the beginning of that downward trend. The presence of plague in both 168 and 200 CE underscores recurring demographic crises that weakened imperial resilience.

Real-World Examples

Historical records from 168 CE include both military campaigns and cultural developments. Marcus Aurelius spent much of the year preparing for renewed conflict after a brief respite in Rome. His return to the Danube frontier underscored the empire’s shifting priorities from internal administration to military defense. Meanwhile, the physician Galen, who treated victims of the Antonine Plague, continued his medical writings, which would later influence Islamic and European medicine for centuries.

Archaeological evidence from this period includes military inscriptions, coinage, and burial sites indicating widespread death. For example, mass graves in Italy and Gaul have been linked to plague outbreaks around this time. Roman coinage from 168 CE often bore the image of Salus, the goddess of health, reflecting public anxiety over disease.

1. The death of Lucius Verus in early 169 CE, likely from plague, occurred after events of 168 CE set the stage.
2. Marcus Aurelius’ return to Carnuntum in Pannonia to lead troops against Germanic tribes.
3. The treaty with the Marcomanni broke down, leading to renewed hostilities in 168.
4. Increased recruitment of non-citizens into the Roman army due to manpower shortages from plague and war.

Why It Matters

The year 168 CE is significant not only for its immediate events but for its long-term implications on Roman and world history. It represents a threshold where the empire began transitioning from internal prosperity to external vulnerability. The challenges faced during this year—plague, war, and leadership strain—foreshadowed the Crisis of the Third Century, a period of near-collapse that followed just decades later.

• Impact on Military: The Marcomannic Wars forced Rome to station legions permanently on frontiers, altering military strategy.
• Demographic Decline: The Antonine Plague reduced the population, affecting tax revenue and agricultural output.
• Philosophical Legacy: Marcus Aurelius wrote Meditations during this period, influencing Stoic thought for centuries.
• Shift in Imperial Focus: Emperors increasingly prioritized military leadership over civil governance.
• Precedent for Crisis: 168 CE set a pattern of plague and invasion repeated in later centuries, such as the Cyprian Plague in 250 CE.

Understanding 168 CE helps contextualize the decline of one of history’s greatest empires. It was not a single event but a confluence of factors—epidemic, war, and leadership change—that collectively weakened Rome’s foundations. As such, this year serves as a critical case study in how even the most powerful civilizations can face systemic challenges that undermine their stability. Its legacy endures in historical scholarship, medical studies of ancient plagues, and philosophical reflections on resilience in times of crisis.