The insolence of the armies inspired Augustus with fears of a still more alarming nature. The despair of the citizens could only attempt what the power of the soldiers was, at any time, able to execute. How precarious was his own authority over men whom he had taught to violate every social duty! He had heard their seditious clamours; he dreaded their calmer moments of reflection. One revolution had been purchased by immense rewards; but a second revolution might double those rewards. The troops professed the fondest attachment to the house of Cæsar; but the attachments of the multitude are capricious and inconstant. Augustus summoned to his aid whatever remained in those fierce minds of Roman prejudices; enforced the rigour of discipline by the sanction of law; and, interposing the majesty of the senate between the emperor and the army, boldly claimed their allegiance as the first magistrate of the republic.
During a long period of two hundred and twenty years, from the establishment of this artful system to the death of Commodus, the dangers inherent to a military government were, in a great measure, suspended. The soldiers were seldom roused to that fatal sense of their own strength, and of the weakness of the civil authority, which was, before and afterwards, productive of such dreadful calamities. Caligula and Domitian were assassinated in their palace by their own domestics: the convulsions which agitated Rome on the death of the former were confined to the walls of the city. But Nero involved the whole empire in his ruin. In the space of eighteen months four princes perished by the sword; and the Roman world was shaken by the fury of the contending armies. Excepting only this short, though violent, eruption of military licence, the two centuries from Augustus to Commodus passed away, unstained with civil blood, and undisturbed by revolutions. The emperor was elected by the authority of the senate and the consent of the soldiers. The legions respected their oath of fidelity; and it requires a minute inspection of the Roman annals to discover three inconsiderable rebellions, which were all suppressed in a few months, and without even the hazard of a battle…
…The good sense of Vespasian engaged him indeed to embrace every measure that might confirm his recent and precarious elevation. The military oath, and the fidelity of the troops, had been consecrated, by the habits of an hundred years, to the name and family of the Cæsars; and, although that family had been continued only by the fictitious rite of adoption, the Romans still revered, in the person of Nero, the grandson of Germanicus, and the lineal successor of Augustus. It was not without reluctance and remorse that the prætorian guards had been persuaded to abandon the cause of the tyrant. The rapid downfall of Galba, Otho, and Vitellius taught the armies to consider the emperors as the creatures of their will, and the instruments of their licence.
- Gibbon, Edward, and Hugh Trevor-Roper. The Decline and Fall of the Roman Empire. New York: Alfred A. Knopf, 1993. Print. 83-86.