After the death of Tiberius (37 A.D.), the problem of the succession presented to the senate was not an easy one.  In his will, Tiberius had adopted, and thereby designated to the senate as his successors, Caius Caligula, the son of Germanicus, and Tiberius, the son of his own son Drusus.  The latter was only seventeen, and too young for such a responsibility.  Caligula was twenty-seven, and therefore still very young, although by straining a point he might be emperor; yet he did not enjoy a good reputation.  If we except him, there was no other member of the family old enough to govern except Tiberius Claudius Nero, the brother of Germanicus and the only surviving son of Drusus and Antonia.  He was generally considered a fool, was the laughing-stock of freedmen and women, and such a gawk and clown that it had been impossible to put him into the magistracy.  Indeed, he was not even a senator when Tiberius died.

[Illustration:  Caligula.]

As they could not consider him, there remained only Caligula, unless they wished to go outside the family of Augustus, which, if not impossible, was at least difficult and dangerous.  For the provinces, the German barbarians, and especially the soldiers of the legions, were accustomed to look upon this family as the mainstay of the empire.  The legions had become specially attached to the memory and to the race of Drusus and Germanicus, who still lived in the minds of the soldiers as witnesses to their former exploits and virtues.  During the long watches of the night, as their names were repeated in speech and story, their shades, idealized by death, returned again to revisit the camps on the banks of the Rhine and the Danube.  The veneration and affection which the armies had once felt for the Roman nobility were now centered about the family of Augustus.  In this difficulty, therefore, the senate chose the lesser evil, and, annulling a part of the testament of Tiberius, elected Caligula, the son of Germanicus, as their emperor.

The death of Tiberius, however, was destined to show the Romans for the first time that although it was hard to find an emperor, it might even be harder to find an empress.  During the long reign of Augustus, Livia had discharged the duties of this difficult position with incomparable success.  Tiberius had succeeded Augustus, and after his divorce from Julia had never remarried.  There had therefore been a long interregnum in the Roman world of feminine society, during which no one had ever stopped to think whether it would be easy or difficult to find a woman who could with dignity take over the position of Livia.  The problem was really presented for the first time with the advent of Caligula; for, at twenty-seven, he could not solve it as simply as Tiberius had done.  In the first place, it was to be expected that a man of his age would have a wife; secondly, the Lex de maritandis ordinibus made marriage a necessity for him, as for all the senators; furthermore, the head of the state needed to have a woman at his side, if he wished to discharge all his social duties.  The celibacy of Tiberius had undoubtedly contributed to the social isolation which had been fatal both to him and to the state.