In 42 BC, Agrippa probably fought alongside Octavian and Antony in the Battle of Philippi. After their return to Rome, he played a major role in Octavian's war against Lucius Antonius and Fulvia, respectively the brother and wife of Mark Antony, which began in 41 BC and ended in the capture of Perusia in 40 BC. However, Salvidienus remained Octavian's main general at this time. After the Perusine war, Octavian departed for Gaul, leaving Agrippa as urban praetor in Rome with instructions to defend Italy against Sextus Pompeius, an opponent of the Triumvirate who was now occupying Sicily. In July 40, while Agrippa was occupied with the Ludi Apollinares that were the praetor's responsibility, Sextus began a raid in southern Italy. Agrippa advanced on him, forcing him to withdraw. However, the Triumvirate proved unstable, and in August 40 both Sextus and Antony invaded Italy (but not in an organized alliance). Agrippa's success in retaking Sipontum from Antony helped bring an end to the conflict. Agrippa was among the intermediaries through whom Antony and Octavian agreed once more upon peace. During the discussions Octavian learned that Salvidienus had offered to betray him to Antony, with the result that Salvidienus was prosecuted and either executed or committed suicide. Agrippa was now Octavian's leading general.