ABSTRACT
Transmitting power smoothly to a chosen successor had plagued emperors from Augustus to Galba. Augustus devised the mechanism: such powers were conferred on the chosen man that he was a Princeps before his predecessor died and the two formed virtually a collegiate Principate; in the next generation two boys might be trained for future supremacy. All three were magnified and glamorized before the Empire. A natural son was the obvious choice, but only Claudius possessed one, Britannicus, and he was not of a suitable age at the time of his father’s death. Adopting a relative by blood or marriage as a son was a provident substitute legally as effective, but it led to rivalry and instability when other candidates, cognates, were available, as happened when Augustus adopted Tiberius in 4. Before Galba became emperor he was recommended to adopt a relative (propinquus) to improve his chances. In the event, and too late, he made a virtue of going outside his family: none of the emperors who had come to power through adoption within the family, Tiberius, Gaius Caligula (whose father Germanicus was Tiberius’ adopted son), and Nero, had turned out well. But Galba’s selection of the innocuous aristocrat L.Piso Licinianus and his failure to package the deal acceptably for the Guard only hastened his fall. Adult sons were a novelty deployed as an advantage. In January 70 Titus and Domitian were in their thirty-first and twentieth years, and likely to produce sons of their own. The elder, as Tacitus makes C.Licinius Mucianus point out to Vespasian when he urged him act, was already qualified to rule. That solved the problem, at least for quietists and those who accepted this way of transmitting power as legitimate.1
