The distant revolts were more frequent than Gibbon thinks: already, under Tiberius, the legions of Germany would have seditiously constrained Germanicus to assume the Imperial purple.
On the revolt of Claudius Civilis, under Vespasian, the legions of Gaul murdered their general, and offered their assistance to the Gauls who were in insurrection.

Julius Sabinus made himself be proclaimed emperor, &c.

The wars, the merit, and the severe discipline of Trajan, Hadrian, and the two Antonines, established, for some time, a greater degree of subordination .-- W] [Footnote 31: The first was Camillus Scribonianus, who took up arms in Dalmatia against Claudius, and was deserted by his own troops in five days, the second, L.Antonius, in Germany, who rebelled against Domitian; and the third, Avidius Cassius, in the reign of M.Antoninus.
The two last reigned but a few months, and were cut off by their own adherents.

We may observe, that both Camillus and Cassius colored their ambition with the design of restoring the republic; a task, said Cassius peculiarly reserved for his name and family.] In elective monarchies, the vacancy of the throne is a moment big with danger and mischief.

The Roman emperors, desirous to spare the legions that interval of suspense, and the temptation of an irregular choice, invested their designed successor with so large a share of present power, as should enable him, after their decease, to assume the remainder, without suffering the empire to perceive the change of masters.