Removing Sejanus was not easy. Nor is it easy to explain why Tiberius moved against him. Agrippina’s youngest boy, Gaius Caligula had been born on August 31st AD 12. He was reaching adulthood. Perhaps Tiberius decided that he was a better heir than Sejanus. We cannot know why he changed his mind, but he did.

The story is dramatic, but the version we have in Dio (58.4-14) is somewhat incoherent. Tiberius began to send mixed signals about Sejanus. He then claimed to be ill and refused to leave Capri. The illness was prolonged, making people think that he might die. A successor was needed. Sejanus was in Rome and he sought permission to come to Capri. This was refused since Tiberius was intending to come to Rome. Tiberius appears to have sown enough doubt in the minds of the Romans that there was a nervousness around him. Then, a letter came. It was delivered by Macro. Macro assured Sejanus that the letter confirmed Sejanus’ elevation to co-emperor. Sejanus entered the senate meeting to await the letter being read. Macro had already given instructions to Memmius Regulus, the other consul, and to Graecinus Laco, who was prefect of the vigiles (a small military force stationed in Rome to keep order). Laco summoned the vigiles and Macro went to assume command of the praetorians.

The letter was now read out in the senate. It was a long and rambling letter by all accounts, presumably because Tiberius wanted Sejanus detained in the senate while Macro charged about Rome. It began with faint praise and ended with condemnation. The senate was in uproar. Constitutionally, the senate was an advisory body: it advised the consuls on what to do. Memmius asked a single senator whether Sejanus should be imprisoned. The senator, who was presumably a man who could be relied on, agreed. Laco appeared. Sejanus was summoned forward. Laco led him off to prison. The senate dispersed.

Public reactions were unpredictable. It was later rumoured that Tiberius was ready to release Drusus so as to rally support. He had ships ready to sail for the troops in Germany. But the plebs took to the streets to riot against Sejanus and, crucially, the praetorians remained in camp. The senators reassembled later the same day in the Temple of Concord. They condemned Sejanus. He was killed, his body taken from the prison and  thrown into the Tiber. His son and daughter were murdered and his former wife, Apicata, denounced Sejanus and Livilla for the death of Drusus in her suicide note.

Soldier and rioters took to the streets and blood flowed. More was to follow when Tiberius learnt of the murder of his son. Not only were those who had lost friends and relatives to Sejanus now primed for revenge, but the assault on the imperial houses meant that everyone who was associated with Sejanus was likely to be purged.

Sejanus fell from being on the verge of assuming the imperial position to reviled enemy of Rome. The costs of his political fall took far more than him: children too young to have any clue what was happening, far too young to have played any political role were brutally murdered. The news of his fall reverberated across the empire and was celebrated in communities which wished to demonstrate their loyalty to the emperor. One presumes that many of these communities had just as anxiously sought to praise Sejanus just a few months earlier.

• What lessons would they have drawn from the Sejanus episode?
• What lessons did future generations of Romans draw from the episode when they encountered it in their histories?

Livilla was killed, either on the orders of Tiberius or by her mother.

Questions

• Why did Tiberius raise up Sejanus?
• Why did so many support Sejanus?
• Was Roman politics under Tiberius the politics of the court or the politics of the senate?
• Why did Tiberius destroy Sejanus?
• Why did Sejanus’ political support (including the praetorian guard) not save him?

Sejanus as Partner in Power                                                                   Late Tiberius and the Senate