Passage: Sextus Pompeius threatened Octavian in Italy by denying shipments of grain through the Mediterranean Sea to the peninsula. Pompeius' own son was put in charge as naval commander in the effort to cause widespread famine in Italy. Pompeius' control over the sea prompted him to take on the name Neptuni filius, "son of Neptune". A temporary peace agreement was reached in 39 BC with the treaty of Misenum; the blockade on Italy was lifted once Octavian granted Pompeius Sardinia, Corsica, Sicily, and the Peloponnese, and ensured him a future position as consul for 35 BC.The territorial agreement between the triumvirate and Sextus Pompeius began to crumble once Octavian divorced Scribonia and married Livia on 17 January 38 BC. One of Pompeius' naval commanders betrayed him and handed over Corsica and Sardinia to Octavian. Octavian lacked the resources to confront Pompeius alone, however, so an agreement was reached with the Second Triumvirate's extension for another five-year period beginning in 37 BC.In supporting Octavian, Antony expected to gain support for his own campaign against the Parthian Empire, desiring to avenge Rome's defeat at Carrhae in 53 BC. In an agreement reached at Tarentum, Antony provided 120 ships for Octavian to use against Pompeius, while Octavian was to send 20,000 legionaries to Antony for use against Parthia. Octavian sent only a tenth of those promised, however, which Antony viewed as an intentional provocation.Octavian and Lepidus launched a joint operation against Sextus in Sicily in 36 BC. Despite setbacks for Octavian, the naval fleet of Sextus Pompeius was almost entirely destroyed on 3 September by General Agrippa at the naval Battle of Naulochus. Sextus fled to the east with his remaining forces, where he was captured and executed in Miletus by one of Antony's generals the following year. As Lepidus and Octavian accepted the surrender of Pompeius' troops, Lepidus attempted to claim Sicily for himself, ordering Octavian to leave. Lepidus' troops deserted him, however, and defected...

Question: Who betrayed Pompeius?
One of Pompeius' naval commanders betrayed him