Such efforts to see Caesar's will done helped raise Octavian's standing with the Roman people considerably. Many of the senators, too were opposed to Antony. Octavian, appreciated as Antony's primary rival by then, was granted the status of senator, despite not yet being twenty.
During the summer of 44 BC the senate's leader, Cicero, delivered a series of infamous speeches against Marc Antony which came to be known as the 'Philippics'. Cicero saw in the young Octavian a useful ally. So, when in November 44 BC Antony left Rome to take command in northern Italy, Octavian was dispatched with the senate's blessing to make war on Antony. Marc Antony was defeated at Mutina (43 BC) and forced to retreat into Gaul.
But now it showed that Cicero had definitely lost control of the young Octavian. Had the two reigning consuls both been killed in the battle, then in August 43 BC Octavian marched on Rome and forced the senate to accept him as consul. Three months thereafter he met with Antony and Lepidus at Bologna and the three came to an agreement, the Triumvirate. This agreement between Rome's most powerful men thoguh completely the senate from power (27 November 43 BC). Cicero was killed in the proscriptions that followed. Brutus and Cassius, Caesar's chief assassins, were defeated at Philippi in northern Greece.
Octavian and Marc Antony, the winners at Philippi, reached a new agreement in October 40 BC in the Treaty of Brundisium. The Roman empire was to be divided between them, Antony taking the east, Octavian the west. The third man, Lepidus, was no longer an equal partner. He therefore had to make do with the province of Africa. To further strengthen their agreeement, Antony married Octavians' sister Octavia. But it was not to be long, before Antony abandoned her to return to Cleopatra. Meanwhile Octavian's own standing had been heightened by the deification of Julius Caesar in early 42 BC. He was no longer to be addressed as 'Octavian' but insisted on being called 'Caesar' and he now styled himself as 'divi filius' - 'son of god'. He used the following years to strengthen his hold over the western provinces. Also in this time Marcus Agrippa, Octavian's most loyal friend, delivered Italy from the menace of the fleet of Sextus Pompeius, a son of Pompey the Great.


As Lepidus fell by the wayside during the conflict with Sextus Pompeius, this left Antony and Octavian rulers of the Roman world. Antony lived openly with Cleopatra, queen of Egypt.