Augustus

=== First conflict with Antony ===
With opinion in Rome turning against him and his year of consular power nearing its end, Antony attempted to pass laws that would assign him the province of [[Cisalpine Gaul]].{{Sfn|Eck|Takács|2003|pages=11–12}}{{Sfn|Rowell|1962|page=21}} Octavian meanwhile built up a private army in Italy by recruiting Caesarian veterans, and on 28 November he won over two of Antony's legions with the enticing offer of monetary gain.{{Sfn|Syme|1939|pages=123–126}}{{Sfn|Eck|Takács|2003|page=12}}{{Sfn|Rowell|1962|page=23}}

In the face of Octavian's large and capable force, Antony saw the danger of staying in Rome and, to the relief of the Senate, he left Rome for Cisalpine Gaul, which was to be handed to him on 1 January.{{Sfn|Rowell|1962|page=23}} However, the province had earlier been assigned to [[Decimus Junius Brutus Albinus]], one of Caesar's assassins, who now refused to yield to Antony. Antony besieged him at [[Modena|Mutina]]{{Sfn|Rowell|1962|page=24}} and rejected the resolutions passed by the Senate to stop the fighting. The Senate had no army to enforce their resolutions. This provided an opportunity for Octavian, who already was known to have armed forces.{{Sfn|Eck|Takács|2003|page=12}} Cicero also defended Octavian against Antony's taunts about Octavian's lack of noble lineage and aping of Julius Caesar's name, stating "we have no more brilliant example of traditional piety among our youth."{{Sfn|Chisholm|Ferguson|1981|page=29}}

At the urging of Cicero, the Senate inducted Octavian as senator on 1 January 43&nbsp;BC, yet he also was given the power to vote alongside the former consuls.{{Sfn|Eck|Takács|2003|page=13}}{{Sfn|Rowell|1962|page=23}} In addition, Octavian was granted ''[[imperium]] [[promagistrate|pro praetore]]'' (commanding power) which legalized his command of troops, sending him to relieve the siege along with [[Aulus Hirtius|Hirtius]] and [[Gaius Vibius Pansa Caetronianus|Pansa]] (the consuls for 43&nbsp;BC). {{Sfn|Eck|Takács|2003|page=13}}{{Sfn|Syme|1939|page=167}} He assumed the ''[[fasces]]'' on 7 January,{{sfn|Fishwick|2004|p=250}} a date that he would later commemorate as the beginning of his public career.{{Sfn|Rowell|1962|page=24}}{{Sfn|Eck|Takács|2003|page=13}}{{Sfn|Gruen|2005|page=160}} Antony's forces were defeated at the battles of [[Battle of Forum Gallorum|Forum Gallorum]] (14 April) and [[Battle of Mutina|Mutina]] (21 April), forcing Antony to retreat to [[Gallia Narbonensis|Transalpine Gaul]]. Both consuls were killed, however, leaving Octavian in sole command of their armies.{{Sfn|Syme|1939|pages=173–174}}{{Sfn|Scullard|1982|page=157}} These victories earned him his first acclamation as ''[[imperator]]'', a title reserved for victorious commanders.{{sfn|Fishwick|2004|p=250}}

The Senate heaped many more rewards on Decimus Brutus than on Octavian for defeating Antony, then attempted to give command of the consular legions to Decimus Brutus.{{Sfn|Rowell|1962|pages=26–27}} In response, Octavian stayed in the [[Po Valley]] and refused to aid any further offensive against Antony.{{Sfn|Rowell|1962|page=27}} In July, an embassy of [[centurion]]s sent by Octavian entered Rome and demanded the consulship left vacant by Hirtius and Pansa{{Sfn|Chisholm|Ferguson|1981|pages=32–33}} and also that the decree should be rescinded which declared Antony a public enemy.{{Sfn|Rowell|1962|page=27}} When this was refused, he marched on the city with eight legions.{{Sfn|Rowell|1962|page=27}} He encountered no military opposition in Rome and on 19 August 43&nbsp;BC was elected consul with his relative [[Quintus Pedius (consul)|Quintus Pedius]] as co-consul.{{Sfn|Eck|Takács|2003|page=15}}{{Sfn|Rowell|1962|page=28}} Meanwhile, Antony formed an alliance with [[Lepidus|Marcus Aemilius Lepidus]], another leading Caesarian.{{Sfn|Syme|1939|pages=176–186}}