That was Caligula’s second response to the conspiracy by his consular “friends.” After having himself unmasked the pretense of friendship between emperor and aristocracy, for a cynical humiliation he made use of the fact that nonetheless no other alternative possibility for their conduct was available. He treated his aristocratic “friends”—that is, the aristocracy as a whole — as if their friendship toward him were actually sincere. Since no one could deny it, given their behavior, he was able to damage them financially as well. They were helpless, and Caligula is said to have made no secret of how much enjoyment that gave him.
Similarly, he compelled senators to pay large amounts of money to sponsor games in Rome. Presumably after the reintroduction of popular elections, he reinstated the old custom of choosing two praetors by lot to present gladiatorial games. Further, he put up his own gladiators for sale and attended the auction in person; his presence had the effect of driving up the prices, since bidders felt obligated to do him a favor in this way. Suetonius provides an account of how Caligula could indulge his sense of humor at senators’ expense during such auctions: “A well-known incident is that of Aponius Saturninus; he fell asleep on one of the benches, and as the auctioneer was warned by Gaius not to overlook the Praetorian gentleman who kept nodding to him, the bidding was not stopped until thirteen gladiators were knocked down to the unconscious sleeper at nine million sesterces” (Suet. Cal. 38.4).
He did not stop there. Dio reports how Caligula invited Incitatus (“Hotspur”), his favorite race horse, to dinner, fed him barley corn made of gold, toasted him with golden goblets, and planned to make him a consul. The meaning of this last gesture, perhaps the emperor’s most notorious, which seems to make no sense, can be inferred from the parallel account by Suetonius, who reports that in addition to a marble stall, a manger made of ivory, and purple blankets, Caligula gave his horse a palace, a staff of servants, and a dinner service so that the guests received in his name could be entertained as grandly as possible. Lastly Suetonius also mentions that the emperor planned to appoint the horse to the consulship.
There is no way now to know whether everyone in Rome got this joke. Nor can we tell whether Suetonius understood it later or — as seems more likely — failed to understand it on purpose, since he makes use of it to present the emperor as insane. There can be no doubt, however, about who in Rome would have gotten the point at the start of 39. The households of the senators — their houses, servants, and dinner services — represented a central manifestation of their social status and were in part an item of ruinous competition that was served up at wasteful banquets, and laws were passed from time to time to restrict extravagance. Achieving the consulship remained the most important goal of an aristocrat’s career. To equip the emperor’s horse with a sumptuous household and to destine it for the consulship satirized the main aim of aristocrats’ lives and laid it open to ridicule. Caligula placed his horse on the same level as the highest-ranking members of society — and by implication equated them with a horse.
Besides symbolically devaluing the Roman consulars, Caligula’s designation of Incitatus as a consul sent a further message: The emperor can appoint anyone he likes to the consulship; consulars are consulars by the grace of the emperor. In fact there was no alternative to the system that awarded status to members of the upper class in Rome according to their standing in the Senate, a form of ranking that had been in place for centuries. But if an individual possessed the minimum requirements — being in the third freeborn generation and of unblemished character — his position within this hierarchy was now decided by the emperor. In fact the emperor could even grant the rights of free birth, ingenuitas, and so make knights even of men born as slaves. Caligula’s joke about his horse not only made the consulars look ridiculous, but also expressed a truth about Roman society that members of the highest rank found extremely disagreeable: The position of every one of them depended on the emperor’s goodwill.
All this, then, was Caligula’s response to the unexpected attempt on his life by the consulars: Instead of issuing orders for heads to roll indiscriminately, he took aim at their positions in the Senate, in relationships of patronage, and in the hierarchy of their society — confronting them with the unpleasant reality of the Empire and with their own duplicitous behavior in dealing with their lack of real power. He forced them to humiliate themselves. He dishonored them by cynicism and symbolic acts. He left them to their impotence and absurdity.
Was this radical shift of behavior on the emperor’s part “appropriate”? The extent to which it was or was not cannot be determined with certainty, since the sources are silent on the motive for the conspiracy that preceded the shift and on its scope and object. That Caligula was still following a policy of demonstrative cooperation with the Senate at the start of the year, however, suggests that something extreme had occurred. In any case one feature of Caligula’s response is clear. Striking at the core of the senatorial aristocracy’s position in society had the desired effect. Conflict between emperor and aristocracy had suddenly erupted, and now the groundwork had been laid for its escalation. The only question was what would be the next opportunity for venting the stored-up hatred. The wait was not long, and the occasion came with two measures intended to stabilize the emperor’s position.
In the summer of the year 39 Caligula remarried. He was again attempting to clarify the dynastic situation by having an heir. The bride, Milonia Caesonia, is said to have been neither young nor particularly beautiful, but she had already proved her fertility by having borne three children — and she was well along in a pregnancy. After the baby was born, Caligula referred to Caesonia as his wife and acknowledged the daughter, who was named Julia Drusilla, as his own. The order of events indicates that this time the emperor waited to marry until a child had actually been born, a child who represented the purpose of the union.
There was a not inconsiderable side effect to Caligula’s now having legitimate offspring, however. His sisters, Agrippina and Livilla, and their descendants were apparently to be permanently removed from possible succession to the throne. Yet Agrippina in particular had demonstrated her ambitions for the succession a year and a half earlier (and would do so again in later years). When her marriage to Gnaeus Domitius Ahenobarbus, a very aristocratic but ailing older man, had produced a son, the later emperor Nero, she had asked Caligula to name the child. Her hopes that the emperor would choose “Gaius” and thereby grant him a special place in the dynasty were in vain, however. Caligula instead suggested the name of their uncle, Claudius, a member of the imperial family whom no one took seriously at that time. Now, with the birth of Caligula’s daughter, Agrippina’s chance to be the mother of an emperor was tending toward zero. She now shared the situation of Aemilius Lepidus, who had lost a once promising position after the death of Drusilla.
The build-up for a military campaign against hostile tribes in Germania led to a further and lasting consequence. As later events would show, Caligula, given the state of his relations with the aristocracy, was preparing this expedition with great urgency in the months following the conspiracy. Since 29, the Roman commander on the upper Rhine had been the senator Gnaeus Cornelius Lentulus Gaetulicus. He had survived Sejanus’s fall despite their having had a close connection, though there were rumors that Tiberius had issued a barely veiled threat to him at that time. Gaetulicus had written to the emperor, according to Tacitus’s account, that he would remain loyal, but if the emperor named a successor the commander would regard it as a certain death sentence. Gaetulicus proposed a kind of bargain, whereby the emperor would remain in charge of the rest of the Empire, but he would keep his province. At the time he got away with it. He had achieved great popularity with his soldiers, though clearly at the expense of discipline. The attacks by tribes in the region, Caligula’s official reason for his campaign, were probably a consequence of Gaetulicus’s long command; at the very least he had to accept responsibility for them. The way Caligula had proceeded against corrupt magistrates in Rome and the prospect that the emperor would soon arrive in the Rhineland in person must have prompted in the senator well-founded fears about his future fate.