Era of the Five Good Emperors
Hadrian died in July 138 having arranged a succession that produced what Machiavelli and Gibbon regarded as the best period of Roman government. The five emperors — Nerva, Trajan, Hadrian, Antoninus Pius and Marcus Aurelius — ruled from 96 to 180, and the system that produced them was adoption rather than blood. Each chose a capable adult successor and adopted him formally, which removed the two failure modes of hereditary monarchy: the incompetent son, and the vacuum that invites civil war. Nerva was an elderly senator installed after Domitian's murder, who adopted Trajan under pressure from the guard. Trajan adopted Hadrian on his deathbed, or Hadrian's supporters said he had. Hadrian's own arrangement was elaborate — he adopted Antoninus Pius on condition that Antoninus in turn adopt both Marcus Aurelius and Lucius Verus, fixing two generations at once. Gibbon called this the period in the history of the world during which the condition of the human race was most happy and prosperous, which is a judgement made from the senatorial sources and about the governing class. The empire was at its greatest extent, the frontiers were quiet, provincial elites were entering the senate, and the emperors were increasingly provincial themselves — Trajan and Hadrian were Spanish. The system was not a principle. Every one of the five except Marcus lacked a surviving son, which is why they adopted. Marcus had one, and Commodus succeeded. He was nineteen, and the empire's decline is conventionally dated from him. Merit had been chosen four times only because nature had left no alternative.
- Year: 96 CE
- Category: Political
