Friend to Octavian After Octavian's return to Rome, he and his supporters realised they needed the support of legions. Agrippa helped Octavian to levy troops in
Campania. Once Octavian had his legions, he made a pact with
Mark Antony and
Lepidus, legally established in 43 BC as the
Second Triumvirate. Octavian and his consular colleague
Quintus Pedius arranged for Caesar's assassins to be prosecuted
in their absence, and Agrippa was entrusted with the case against
Gaius Cassius Longinus. It may have been in the same year that Agrippa began his political career, holding the position of
tribune of the plebs, which granted him entry to the
Senate. 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 BC, 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 BC 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.
Governor of Transalpine Gaul In 39 or 38 BC, Octavian appointed Agrippa governor of
Transalpine Gaul, where in 38 BC he put down a rising of the
Aquitanians. He also fought the
Germanic tribes, becoming the next Roman general to cross the
Rhine after
Julius Caesar. He was summoned back to Rome by Octavian to assume the
consulship for 37 BC. He was well below the usual minimum age of 43, but Octavian had suffered a humiliating naval defeat against Sextus Pompey and needed his friend to oversee the preparations for further warfare. Agrippa refused the offer of a
triumph for his exploits in Gaul – on the grounds, says
Dio, that he thought it improper to celebrate during a time of trouble for Octavian. Since Sextus Pompeius had command of the sea on the coasts of Italy, Agrippa's first care was to provide a safe harbour for Octavian's ships. He accomplished this by cutting through the strips of land which separated the
Lacus Lucrinus from the sea, thus forming an outer harbour, while joining the
lake Avernus to the Lucrinus to serve as an inner harbour. The new harbour complex was named
Portus Julius in Octavian's honour. Agrippa was also responsible for technological improvements, including larger ships and an improved form of
grappling hook. About this time, he married
Caecilia Pomponia Attica, daughter of
Cicero's friend
Titus Pomponius Atticus.
War with Sextus Pompeius In 36 BC, Octavian and Agrippa set sail against Sextus. The fleet was badly damaged by storms and had to withdraw; Agrippa was left in charge of the second attempt. Thanks to superior technology and training, Agrippa and his men won decisive victories at
Mylae and
Naulochus, destroying all but seventeen of Sextus' ships and compelling most of his forces to surrender. Octavian, with his power increased, forced the triumvir Lepidus into retirement and entered Rome in triumph. Agrippa received the unprecedented honour of a
corona navalis decorated with the beaks of ships; as Dio remarks, this was "a decoration given to nobody before or since". ==Public service==