In addition to Caligula’s indifference to the fate of his family and his successful opportunism in dealings with the emperor and his circle, Suetonius reports that during his time on Capri the later emperor was already unable to conceal his brutal and depraved character. Caligula “was a most eager witness of the tortures and executions of those who suffered punishment, reveling at night in gluttony and adultery, disguised in a wig and a long robe, passionately devoted besides to the theatrical arts of dancing and singing, in which Tiberius very willingly indulged him, in the hope that through these his savage nature might be softened. This last was so clearly evident to the shrewd old man that he used to say now and then that to allow Gaius to live would prove the ruin of himself and of all men” (Suet. Cal. 11).
It is easy enough to assess this account if one takes into consideration the general situation as it is reported in other, unjaundiced passages that do not touch on Caligula. From Tacitus’s account, cited above, we know that after the death of Sejanus the demeanor of those present was carefully observed when guilty sentences were announced or executions were carried out, in an attempt to discern any indication of hostility toward the emperor. Any such sign perceived in a person’s reaction was reported. Thus if Caligula was present at executions on Capri — an occurrence reported nowhere else — he was probably under close observation also. Not too much significance for interpreting his character should be attached to his failure to display much emotion. Furthermore, no evidence survives, written or archeological, to suggest the existence of taverns, brothels, or theaters on the island at that time. Or to put it more precisely: The milieu on Capri was not that of a large city like Rome, where it was easy to move about incognito. Furthermore, there are no indications that on occasional visits to the mainland Caligula would have been able — or would have wanted — to absent himself from the emperor’s entourage. Suetonius has thus ascribed to him attributes reported from the youth of a later emperor in Rome who was similarly hated, namely Nero. Finally, the suggestion that the old emperor saw through Caligula’s deception explicitly contradicts reports by Suetonius himself and others of Caligula’s ability to dissimulate, which he had perfected and which probably saved his life on Capri. It also contradicts everything that can be inferred about Tiberius’s own personality from accounts of his behavior over many years. Tiberius’s most notable trait was placing too much trust in one person (Sejanus) and responding with exaggerated distrust to everyone else; if he had one failing, it was precisely the lack of what is claimed for him in this passage: a sound knowledge of human nature. Suetonius’s account is thus utterly false. He has projected alleged qualities of the later “evil” emperor Caligula back into the time of his residence on Capri.
For Caligula’s ultimately successful path to the imperial throne, the support of Macro, prefect of the Praetorian Guard, was decisive. All the sources are unanimous on that point. They also agree that intrigue was involved, as was only to be expected in view of the emperor’s failure to settle on a successor. Exactly how this intrigue played out cannot be determined, but that very fact suggests its secrecy was well planned — whether by Caligula himself, by Macro, or by Ennia, the prefect’s wife.
After Junia Claudilla died in childbirth, Caligula and Ennia are supposed to have begun an affair. Philo reports the “widespread view” that because she had a sexual relationship with Caligula she was able to persuade her husband to defend her lover when others denounced him to Tiberius, and also to support Caligula as an aspirant to the throne. If this version is correct, then the intrigue probably originated in Ennia’s ambition to become empress. According to Suetonius, however, Caligula seduced Ennia and promised to marry her, so that she would intervene with Macro and gain his backing. Tacitus, and similarly Cassius Dio, reports a third version, that it was Macro who attempted to win Caligula’s favor by inducing Ennia to have an affair with him, hoping that a bond with the wife would also extend to the husband. This last version is certainly the most implausible. It presumes that Caligula’s succession was a foregone conclusion, regardless of whether Macro supported him or not, so that Caligula would have had no reason to seek Macro’s favor. Macro, however, is generally depicted as the most powerful man of that day after the emperor.
It is difficult to assess the situation because we do not know how often Macro visited Capri, where Ennia must have spent considerable time. Her relationship with the future emperor probably was not sexual at all, and the married couple was simply paving the way for Caligula’s succession through a division of labor — with Macro machinating in Rome and Ennia on Capri in the role of Caligula’s confidante. Such an interpretation would fit well with the harmonious relationship among the three in the first few months after Caligula’s accession to the throne. Yet whatever the details of the intrigue were, it involved bypassing the emperor and his grandson to contrive the succession. It was an extremely risky enterprise, but again Caligula prevailed.
He seems to have remained in danger until the very end, however. Several sources report that Tiberius was concerned for the safety of his grandson, then seventeen years old, if Caligula should become emperor. Philo writes that Macro saved Caligula’s life several times on Capri; he also mentions reports that Caligula would have been eliminated if Tiberius had lived only a little while longer, for very serious allegations had been raised against him. These charges may refer to the intrigue concerning the succession. According to Philo, toward the end of his life Tiberius was planning to name his biological grandson as his successor. Dio tells a different story: Tiberius considered Gemellus illegitimate, the child of Livilla’s liaison with Sejanus, and therefore he preferred Caligula. Josephus provides yet another version, that Tiberius decided to regard a chance occurrence as an omen and indicator of God’s will. The conflicting accounts suggest that the succession was an open question until the last moment. Tacitus probably came closest to the truth when he concluded that Tiberius could not summon the strength to make a decision.
Tiberius died on 16 March in the year 37. In the preceding weeks the old man had approached the city of his birth for the last time, but he died at Misenum, the base of the Roman fleet. Various rumors about his death found their way into circulation. According to one, after death seemed to have occurred and preparations were already under way to proclaim Caligula emperor, Tiberius is supposed to have regained consciousness suddenly and asked for food. While everyone else present stood rooted to the spot in terror, Macro ran into the bed chamber, threw covers over the emperor, and smothered him. Another version declared that Caligula had hastened his adoptive grandfather’s demise, first with poison and then by strangling him with his own hands. According to a third account, Caligula had first starved the emperor and then suffocated him with Macro’s help. Regardless of how the emperor actually died, even in their diversity the reports of the death of the emperor — who over the years had become ever more odious — confirm the contemporaries’ image of the center of power, where Caligula had lived for six years: All who took part were in mortal peril.
The same day, members of the Praetorian Guard in Misenum proclaimed Caligula imperator. Following arrangements with the consuls and leading senators, the Roman Senate accepted the new disposition of power. On 18 March Tiberius’s last will and testament was set aside on the grounds that he had been of unsound mind when he made it. The Senate — an ancient and honorable institution that in the preceding two decades had both lost a large number of members to violence and suffered a decline in morale — recognized the son of Germanicus as emperor in absentia. After his arrival in Rome on 28 March, “the right and the power to decide on all affairs” was conferred on him (Suet. Cal. 14.1). With this step Caligula, at the age of twenty-four, became Gaius Caesar Augustus Germanicus and ruler of the Roman Empire.