While admitting that the idea of a hereditary monarchy “seems to present the fairest scope for ridicule” (167), Gibbon argues it is a form of government where conflicts over the succession of the leadership are least likely to occur. He further asserts that in any country, the army is the most powerful force among the population. If there is a firmly established right to the throne that even the army must acknowledge, the risk of civil war and competing factions is reduced. No such rigid principle of legitimacy existed in the Roman Empire. Following the downfall of Alexander Severus, “no emperor could think of himself safe upon the throne, and every barbarian peasant on the frontier might aspire to that august but dangerous station” (168).

Returning to his narrative, Gibbon describes how the army hatched a plot to overthrow Alexander Severus and replace him with a “real soldier” (170), Maximin, a peasant from Thrace who became a distinguished military tribune. Alexander and his mother, Julia Mamaea, were both killed by the troops while on an army campaign in the east. Gibbon notes that previous tyrannical emperors like Caligula, Commodus, and Caracalla were “all dissolute and inexperienced youths” (171).