138, after a long reign dedicated to the cultural unification and consolidation of the empire, the Emperor Hadrian named Antoninus Pius his son and heir, under the condition that he adopt both Marcus Aurelius and Lucius Verus. Hadrian died that same year, and Antoninus began a peaceful, benevolent reign. He adhered strictly to Roman traditions and institutions, and shared his power with the Roman Senate. Marcus Aurelius and Lucius Verus succeeded Antoninus Pius in 161 upon that emperor's death, and co-ruled until Verus' death in 169. Marcus continued the Antonine legacy after Verus' death as an unpretentious and gifted administrator and leader. He died in 180 and was followed by his biological son, Commodus. Five Good Emperors The rulers commonly known as the "Five Good Emperors" were Nerva, Trajan, Hadrian, Antoninus Pius, and Marcus Aurelius. The term was coined by Niccolò Machiavelli in his posthumously published book The Discourses on Livy from 1531: Machiavelli argued that these adopted emperors earned the respect of those around them through good governing: Edward Gibbon wrote in The History of the Decline and Fall of the Roman Empire that their rule was a time when "the Roman Empire was governed by absolute power, under the guidance of wisdom and virtue". Gibbon believed that these benevolent monarchs and their moderate policies were unusual and contrasted with their more tyrannical and oppressive successors. Alternative hypothesis One hypothesis posits that adoptive succession arose because of a lack of biological heirs. All but the last of the adoptive emperors had no legitimate biological sons to succeed them. They were therefore obliged to pick a successor somewhere else; as soon as the Emperor could look towards a biological son to succeed him, adoptive succession was set aside. The dynasty may be broken up into the Nerva–Trajan dynasty (also called the Ulpian dynasty after Trajan's gentile name 'Ulpius') and Antonine dynasty (after their common name Antoninus). Note: Marcus Aurelius co-reigned with Lucius Verus from 161 until Verus' death in 169. References Roman imperial dynasties 96 establishments 192 disestablishments 90s establishments in the Roman Empire 2nd-century disestablishments in the Roman Empire