With the death of the penultimate Good Emperor Antoninus Pius, Marcus Aurelius loomed unchallenged to inherit the emperorship, even though he had already held de facto imperium for over the past decade. Nonetheless, Marcus reneged the assumptive power of sole rule, instead opting to apportion control with his stepbrother Lucius Verus. Marcus’ early life would lay the foundation for both his prodigious political and literary careers that would solidify his image as the beloved philosopher-king. Perhaps the most crucial event that would shape Marcus as a major political player was his adoption by Annius Verus who was his grandfather and relative of the emperor Hadrian. Hadrian immediately took to the young Marcus and favored him over Verus, then Lucius Commodus. Marcus’ connection to such an influential figure catapulted him through the cursus honorum, becoming quaestor in 139 AD, consul in 140 and again in 145.
After Marcus assumed sovereignty in 161 from Antoninus, he declared his adoptive-brother Lucius as co-emperor, and they became the first de facto rulers of Rome. Their reign focused on fighting rebellions in the east from Parthians in Armenia and Mesopotamia and in the north from the Marcomanni and the Quadi along the Danube. Unlike Trajan, the second of the Five Good Emperors, Marcus Aurelius did not create any new provinces or annex territory for the Roman Empire, which saw its greatest area in land holdings under Trajan. Marcus, known for his rationality, inquisitiveness, pragmatism, and intellect, waged more defensive military campaigns to sustain domestic stability rather than an active, bellicose strategy. Tutored by a plethora of notable, erudite scholars, Marcus was most influenced by Fronto the orator and Iunius Rusticus, as well as Stoic, Platonic, and Epicurean philosophy. Always an eager learner, he preferred shrewd decision over bold action which further adds to his lack of military experience and training when waging wars as emperor, which is why he constantly surrounded himself with a diverse group of advisers and staff.
Wars of 161-169
From 162 to 166, Lucius Verus was sent from Rome to be stationed at Antioch to serve as the titular head of the expeditionary forces. The general Statius Priscus expelled the Parthians from Armenia in 163, allowing Verus to take the title Armeniacus and Marcus followed suit a year later in 164. Avidius Cassius defeated the Parthians in Mesopotamia in 165, and Verus took Parthicus Maximus in the same year (Marcus after a similar delay) and they both took Medicus in 166.
Marcus and Lucius attempted to launch a northern campaign along the Danube, but a devastating plague claimed the life of Lucius Verus in 169.
Wars of Marcus Aurelius 170-180
Marcus’ initial campaign of the Danube was routed by the Marcomanni and Quadi tribes. Pompeianus and Publius Helvius Pertinax drove them from Italy, Noricum, and Pannonia. In 172 Marcus defeated the Marcomanni and took the title Germanicus and followed with a victory over the Quadi in 173. With Marucs then stationed at Sirmium in 174, his general Avidius Cassius, who had conquered the parthians a decade before, staged a coup in the east, having been pronounced emperor himself. The revolt broke down, and Marcus, proclaimed Sarmaticus, took a tour of the East with the imperial family through Asia, Syria, Egypt, and Athens, finally returning to Rome with great triumph and welcome from the citizens in 176. Marcus spent the last two years of his life trying to annex the territory of Marcomannia and Sarmatia, but he died in 180 before he could do so.