It seems, then, that the campaign against the Britons may have failed because of a mutiny in which legions I and XX took part; both had refused to fight in A.D. 14 and had now joined Caligula’s forces from their original station on the Rhine. This conclusion is supported by Anthony Barrett’s analysis of circumstances within Britain. In his view, the general conditions would definitely have favored an aspiring conqueror at that time, if Caligula and his troops had only mounted an attack.
Looking at the enormous expense and effort Caligula’s military campaigns required, Tacitus characterizes them as ludicrous and attributes their failure to the emperor’s capricious nature. In fact Caligula achieved no conquests worth mentioning. An impartial assessment must record, however, that he quelled a revolt by the governor of one of the militarily most important provinces in the Empire and corrected deficiencies in the troops along the Rhine that had gone unaddressed for years. Much evidence suggests that Caligula created the conditions in which Claudius was able to conquer Britain three years later. It should also be kept in mind that all long-term planning for military campaigns had to be tossed overboard once the great conspiracy was uncovered, and that the expeditions all were attempted while the situation in Rome was highly uncertain.
Last, there are various indications that the abrupt end of the mission and Caligula’s swift return were prompted by new threats against him from aristocratic circles. In connection with events at the English Channel, Dio mentions that Caligula showed “no little vexation at his commanders who won some slight success” (Dio 59.21.3). This remark points to conflicts between the emperor and the commanding officers of the military, who all came from the senatorial order. Such tensions can hardly have arisen if the officers’ successes were in carrying out the emperor’s orders. Furthermore, the close of military actions coincided with a great intensification of the emperor’s hostility toward the aristocracy as a whole, for which the sources provide no other convincing explanation. On his way back to Rome Caligula encountered another delegation from the Senate asking him to hurry, which suggests there was an urgent need for him to take action in the capital. Thereupon, the account runs, Caligula shouted at the top of his voice, “I will come; I will come, and this will be with me,” tapping the hilt of the sword at his side. At the same time he proclaimed in an edict that “he was returning, but only to those who desired his presence, the equestrian order and the people, for to the Senate he would never more be fellow citizen nor princeps” (Suet. Cal. 49.1). He also gave up plans to celebrate a triumph, and forbade any senators to come out to meet him en route; in other words, he announced that he would have no further social contact with his fellow aristocrats.
The conspiracy of Agrippina, Livilla, and Lepidus had presented Caligula with the same threat in extreme form that had always been present under the rule of his imperial predecessors and that his successors on the throne would face a number of times: The very people who made up the emperor’s closest circle could endanger his safety. Precisely because they were close to the ruler, because they could influence his decisions and allow or deny others access to him, they had power that could also be turned against the emperor himself. This gave rise to a paradoxical situation in which the emperor had to be most mistrustful of the people he trusted most. The problem was exacerbated in the case of a close family relationship or high social standing. Already under the first two emperors this danger had had consequences for the selection of their staff, which had been called into service for precarious power-political tasks. This is seen not only in the equestrian rank of the Praetorian prefects and the governor of Egypt but also on occasion by the employing of freedmen (former slaves) of the emperor’s household in highly confidential posts. These last were particularly well suited for their positions, since in contrast to individuals of high rank or members of the imperial family, freedmen owed everything to the emperor. Without him they were nothing. While they might become a threat to him in court intrigues, they could never aspire to replace him. Caligula was the first Roman emperor systematically to exploit the advantage this group offered.
After Lepidus was executed and the emperor’s sisters banished, we hear nothing more of Roman aristocrats who acquired influence and wealth as members of Caligula’s inner circle or through close personal ties to him. When he appeared in public in the city he was of course still accompanied by a retinue of high-ranking “friends” from the aristocracy, including Claudius, but after the expedition to Gaul the circle of Caligula’s closest confidants and aides consisted of quite different people.
One of the central figures in this group was the freedman Gaius Julius Callistus. Nothing is known about his background. His daughter Nymphidia, mother of the later Praetorian prefect Nymphidius Sabinus under Nero, is said to have been Caligula’s mistress as a young woman; that may be how the two men encountered one another. Callistus appears to have played a role in the detection of the great conspiracy. In this extremely perilous situation it was he who persuaded the emperor to give the consulate to Domitius Afer. In the aftermath, according to Josephus, the fear he inspired in people and his great wealth enabled him to achieve enormous influence and power “no less than a tyrant’s” (Jos. Ant. 19.64). Another close confidant, probably also descended from slaves, was Protogenes. He “assisted the emperor in all his harshest measures” (Dio 59.26.1) and is supposed to have carried around two catalogues labeled “Sword” and “Dagger.” They apparently recorded the behavior of the six hundred members of the Senate (too large a number to keep track of in one’s head) and the intended punishment for each, should the necessity arise — something that caused the secretary to become a terrifying figure for the aristocracy. Another important role was played by the Egyptian slave Helicon, originally a gift for Tiberius, who worked his way up to become Caligula’s valet. Philo reports that Helicon was always at Caligula’s side, doing gymnastic exercises with him, and accompanying him to the baths. Since he remained near the emperor when he ate or slept, Helicon seems to have served some of the functions of a bodyguard as well. He advised Caligula on decisions, controlled access to him, and used his position to his own advantage by taking bribes — or at least that is what Philo claims, who had bad experiences with him.
Another member of the new inner circle around Caligula was the empress Caesonia, who had borne him a daughter and with whom he was passionately in love, according to the sources. She, too, was considered to be an influential adviser and apparently remained in Rome during Caligula’s expedition to the North, acting as his standin. Finally, by virtue of their positions a significant role fell to the two Praetorian prefects. Cassius Dio names both, in addition to Callistus and Caesonia, as the emperor’s most important confidants.
All the above-named people acquired political prominence only after the great conspiracy and Caligula’s sojourn in Gaul. After his experiences in 39 the emperor consciously embarked on a new path in exercising rule. He removed all the aristocrats from his inner circle and thereby also from the political nerve center of the Roman Empire. The background for this measure was the emperor’s need for personal security, and it was directed against Rome’s traditional political institutions, the Senate and magistrates. At the same time, some people outside the center gained importance in political operations although they had no connection at all with the old institutions. Thus, for example, after the events on the shore of the English Channel Caligula authorized his procurators — financial agents — to confiscate funds as they saw fit to pay for his triumph in Rome (the one that was later called off). Officers of the Praetorian Guard were authorized to collect taxes and unpaid tribute as well. In other words, the emperor used the structures available in his household and in the military to administer political tasks for which they had previously had no responsibility.