The Julio-Claudian dynasty was the first Roman imperial dynasty, consisting of the first five emperors: Augustus, Tiberius, Caligula, Claudius, and Nero. They ruled the Roman Empire from its formation under Augustus in 27 BC until 68 AD , when Nero committed suicide. The term “Julio-Claudian” is derived from the two main branches of the imperial family: the Julii Caesares and Claudii Nerones.
Many of the Julio-Claudian emperors struggled to produce a male heir, or one that outlived them. And so adoption became a tool that most Julio-Claudian emperors utilised in order to promote their chosen heir to the front of the succession. Augustus, himself an adopted son of his great-uncle Julius Caesar, adopted his stepson Tiberius as his son and heir. Tiberius was, in turn, required to adopt his nephew Germanicus, the father of Caligula and brother of Claudius. Caligula adopted his cousin Tiberius Gemellus (grandson of Tiberius) shortly before he executed him. And finally, Claudius adopted his great-nephew and stepson Nero, who, lacking a natural or adopted son of his own, ended the reign of the Julio-Claudian dynasty with his fall from power and subsequent suicide.
Lacking any male heir, Augustus married his only child, his daughter Julia, to his nephew M. Claudius Marcellus. Marcellus, unfortunately, died of food poisoning in 23 BC. Augustus then married his daughter to his loyal friend and general, M. Vipsanius Agrippa, previously married to Augustus’ niece, the sister of Marcellus. This marriage produced five children: Gaius Caesar, Lucius Caesar, Julia the Younger, Agrippina the Elder, and Agrippa Postumus.
Gaius and Lucius, were adopted by Augustus and became his heirs; however, Augustus also showed great favour towards Tiberius and Drusus, his wife Livia’s children from her first marriage to Ti. Claudius Nero. This may have been because Gaius and Lucius were too young during this period.
M. Agrippa died in 12 BC, and Tiberius was ordered by Augustus to divorce his wife Vipsania Agrippina, daughter of Agrippa by his first marriage, and marry his stepsister, Julia the Elder. Drusus, the brother of Tiberius, died in 9 BC after falling from a horse whilst returning from campaign in Germania. Tiberius shared in Augustus’ tribune powers, but, in 6 BC, went into voluntary exile in Rhodes. After the early deaths of both Lucius in 2 AD and Gaius in 4 AD and the exile of both Julia the Elder for adultery, Augustus was forced to recognize Tiberius as the next Roman emperor. Tiberius was recalled to Rome and officially adopted by Augustus. By Augustus’ request, Tiberius adopted his nephew Germanicus, son of his late brother Drusus. Germanicus subsequently married Augustus’ granddaughter, Agrippina the Elder.
Despite his difficult relationship with the Senate, Tiberius’ first years were generally good. He stayed true to Augustus’s plans for the succession and favoured his adopted son and nephew, Germanicus, over his natural son, Drusus, as did the Roman populace. On Tiberius’ request, Germanicus was granted proconsular power and assumed command in Germania, where he suppressed the mutiny after Augustus’ death and led army on campaigns against Germanic tribes in 14-16 AD. Germanicus died in Syria in 19 AD and, on his deathbed, accused the governor of Syria, Cn Calpurnius Piso, of murdering him at Tiberius’s orders. With Germanicus dead, Tiberius began elevating his own son Drusus as heir.
By this time Tiberius had left more of the day-to-day running of the Roman Empire to L. Aelius Sejanus, his Praetorian Prefect. Sejanus created an atmosphere of fear in Rome, controlling a network of informers and spies whose incentive to accuse others of treason was a share in the accused’s property after their conviction and death. Treason trials became commonplace; few members of the Roman aristocracy were safe. The trials played up to Tiberius’ growing paranoia, which made him more reliant on Sejanus, as well as allowing Sejanus to eliminate potential rivals.
Tiberius, perhaps sensitive to Sejanu’s ambition, rejected his proposal to marry Livilla, Germanicus’ sister and the widow of Drusus the Younger, who had died in 25 AD. However, in 30 AD, Sejanus was betrothed to Julia Livia, daughter of Livilla and Drusus the Younger, and in 31 AD he held the consulship with Tiberius as his colleague.
Sejanus was summoned to a meeting of the Senate later that year on 18 October 31 AD, and through a letter sent by Tiberius to the Senate, was denounced and put on trial for treason. A purge followed, in which Sejanus and his most prominent supporters were killed. With his son, Drusus the Younger, dead and having had Germanicus’ elder two sons Nero and Drusus convicted of treason and killed, along with their mother Agrippina the Elder, Tiberius chose Caligula, Germanicus’ youngest son, and Tiberius Gemellus, the son of Drusus the Younger, as co-heirs.
Tiberius died at Misenum on 16 March 37 AD. Suetonius writes that his Praetorian Prefect, N. Sutorius Macro, smothered Tiberius with a pillow to hasten Caligula’s accession.
When Tiberius died, Caligula ordered his co-heir, Tiberius Gemellus, to be killed within his first year in power. Backed by N. Sutorius Macro, Caligula asserted himself as sole emperor, though he later had Macro killed as well. Following Gemellus’ death, Caligula marked his brother-in-law, M. Aemilius Lepidus, husband of his sister Julia Drusilla, as his heir. However, after Drusilla’s death, Lepidus was accused of having affairs with Caligula’s other sisters, Agrippina the Younger and Julia Livilla, and he was executed. He had previously had Drusilla’s first husband L. Cassius Longinus killed and upon the death of Agrippina’s husband Cn. Domitius Ahenobarbus, he seized his inheritance.
Several unsuccessful assassination attempts were made on Caligula’s life. The successful attempt was hatched by the disgruntled Praetorian Guard with backing by the Senate. The historian Josephus claims that the conspirators wished to restore the Republic while the historian Suetonius claims their motivations were mostly personal. On 24 January 41 AD, the Praetorian tribune Cassius Chaerea and his men stopped Caligula alone in an underground passage below the Palatine and stabbed him to death. Together with another tribune, Cornelius Sabinus, he killed Caligula’s wife Caesonia and their infant daughter, Julia Drusilla, on the same day.