quality:correction, quality:corruption, structural:expansion
Conflict with Sextus Pompey

While Antony and the other triumvirs ratified the Treaty of Brundisium to redivide the Roman world among themselves, the rebel Sextus Pompey, the son of Caesar's rival Pompey the Great, was largely ignored. From his stronghold on Sicily, he continued his piratical activities across Italy and blocked the shipment of grain to Rome. The lack of food in Rome undermined the triumvirate's political support. This pressure forced the triumvirs to meet with Sextus in early 39 BC.

While Octavian wanted an end to the ongoing blockade of Italy, Antony sought peace in the West in order to make the Triumvirate's legions available for his service in his planned campaign against the Parthians. Though the Triumvirs rejected Sextus' initial request to replace Lepidus as the third man in the triumvirate, they did grant other concessions. Under the terms of the Treaty of Misenum, Sextus was allowed to retain control over Sicily and Sardinia, with the provinces of Corsica and Greece being added to his territory. He was also promised a future position with the Priestly College of Augurs and the consulship for 35 BC. In exchange, Sextus agreed to end his naval blockade of Italy, supply Rome with grain, and halt his piracy of Roman merchant ships. However, the most important provision of the Treaty was the end of the proscription the trimumvirate had begun in late 43 BC. Many of the proscribed senators, rather than face death, fled to Sicily seeking Sextus' protection. With the exception of those responsible for Caesar's assassination, all those proscribed were allowed to return to Rome and promised compensation. This caused Sextus to lose many valuable allies as the formerly exiled senators gradually aligned themselves with either Octavian or Antony. To secure the peace, Octavian betrothed Marcus Claudius Marcellus, Octavian's three-year-old nephew and Antony's stepson, to Sextus' daughter Pompeia. With peace in the West secured, Antony planned to retaliate against Parthia. Under an agreement with Octavian, Antony would be supplied with extra troops for his campaign. With this military purpose on his mind, Antony sailed to Greece with Octavia, where he behaved in a most extravagant manner, assuming the attributes of the Greek god Dionysus in 39 BC.

The peace with Sextus was short-lived, however. When Sextus demanded control over Greece as the agreement provided, Antony demanded the province's tax revenues be to fund the Parthian campaign. Sextus refused. Meanwhile, Sextus' admiral Menas betrayed him, shifting his loyalty to Octavian and thereby granting him control of Corsica, Sardinia, three of Sextus' legions, and a larger naval force. These actions worked to renew Sextus' blockade of Italy, preventing Octavian from sending the promised troops to Antony for the Parthian campaign. This new delay caused Antony to quarrel with Octavian, forcing Octavia to mediate a truce between them. Under the Treaty of Tarentum, Antony provided a large naval force for Octavian's use against Sextus while Octavian promised to raise new legions for Antony to support his invasion of Parthia. As the term of the Triumvirate was set to expire at the end of 38 BC, the two unilaterally extended their term of office another five years until 33 BC without seeking approval of the senate or the assemblies. To seal the Treaty, Antony's elder son Marcus Antonius Antyllus, then only six years old, was betrothed to Octavian's only daughter Julia, then only an infant. With the Treaty signed, Antony returned to the East, leaving Octavia in Italy.