Antonia the Younger (Antonia minor), born 31 January 36 BCE, died 1 May 37 CE, and not to be confused with Antonia the Elder (Antonia maior), her older sister.
Antonia was the second daughter of Marcus Antonius and Octavia. Before Marcus Antonius defected to the East, had an affair with Cleopatra and was defeated by Octavian (his one-time ally, soon-to-become first emperor of Rome and assume the name Augustus) at the Battle of Actium, he was married to Octavia. Octavia was none other than Octavian's sister. The marriage had been intended to cement Octavian's and Marcus Antonius' alliance; it was not perhaps the most successful venture.
Antonia was raised by her mother, along with Octavia's children from her previous marriage to Gaius Claudius Marcellus, and, quite remarkably, Marcus Antonius' children from his earlier marriage to Fulvia and his relationship with Cleopatra. Octavian served as her male guardian and capitalised on her availability as a pawn in his dynastic game.
Antonia was married to Nero Claudius Drusus (not the emperor Nero, he came later), who was the son of Tiberius Claudius Nero. Drusus had been Octavian's ward since 33BCE, when his father died. This marriage was a useful move to help Octavian protect his dynastic interests. Both Antonia and Drusus could have produced offspring who were potential threats to Octavian's authority; by tying together the two lines, it reduced the number of possible challengers and meant that Octavian was able to keep them closer to him; consequently, they were less likely to oppose him.
Antonia bore three children, all of whom are individually interesting: Germanicus Julius Caesar (referred to as Germanicus, born 15 or 16 BCE, much-famed and much-adored general), Livia Julia (born 13 BCE and often referred to as Livilla, scheming adulterer) and Claudius Nero Germanicus (known as Claudius, born 10 BCE, future Emperor). After Drusus' death in 9 BCE, Antonia followed her mother's example and refused to remarry. This choice would have granted her a certain degree of independence; however, she would always remain under the hawkish eyes of whomsoever was head of the Julio-Claudian household at the time. From 29 CE onwards, Antonia cared for two of her grandchildren born to Germanicus and his wife Vipsania Agrippina, Gaius Julius Caesar Germanicus, who was to become better known as the emperor Caligula and his sister, Julia Drusilla.
The event for which Antonia is perhaps most noted is her intervention in the Sejanus Affair of 31 CE. The Praetorian Prefect Lucius Aelius Sejanus had been steadily accruing greater authority in Rome, capitalsing on the absence of the emperor Tiberius, who had retreated to his villa on Capri. By 31CE, Tiberius' position was under threat; it was Antonia who wrote to him, informing him of the danger. This act was a demonstration of Antonia's courage, and maybe something more than that: not only was she risking her life to send the message, but she was incriminating her daughter simultaneously. Livilla stood accused of adultery with Sejanus, the act was classified as treasonable. Tiberius moved against Sejanus; Antonia inflicted punishment on Livilla. It is reported that Antonia locked her daughter in her bedroom and allowed her to starve to death.
During Caligula's reign, Antonia was privileged with the title Augusta, and it seems that she enjoyed a certain degree of influence regarding decisions of Imperial policy. However, Caligula grew tired of her interference and allegedly drove his grandmother to suicide. Suetonius reported that Caligula observed her pyre burn from his dining room window (Suetonius: Caligula, XXIII). Upon becoming Emperor, Claudius worked towards the re-establishment of a positive memory of Antonia, which had suffered under Caligula.
In a world dominated by males and where females had limited rights and influence (it was not as if they had no rights at all, they did have some), it is interesting to find that an area where females did assume a prominent role was in the Imperial Household. Antonia's influence ranged from preserving state security, to upholding moral values, to offering advice.
A footnote to Antonia's story is that her freedwoman, Caenis (who became Antonia Caenis on manumission), was the long-term and publicly-acknowleged lover of the Emperor Vespasian. It seems that Antonia's influence stretched beyond the Julio-Claudian house.