Battle of Mutina

The Battle of Mutina was fought on April 21, 43 BC between the forces of Mark Antony and the forces of Gaius Vibius Pansa Caetronianus and Aulus Hirtius, who were providing aid to Decimus Junius Brutus Albinus.

Prelude
Around one year after Julius Caesar's murder, negotiations between the Roman Senate and Antony broke off. Antony gathered his legions and marched against one of the assassins Decimus Junius Brutus Albinus, who was governor of Cisalpine Gaul.

Mark Antony had Decimus Brutus confined around Mutina (modern Modena), just south of the Padus (Po) River on the Via Aemilia. Pansa was sent north from Rome to link with Hirtius and Octavian in order to provide Brutus with aid. On April 14, Antony marched with his praetorian cohort, the II and the XXXV legions, light-armed troops and a strong body of cavalry to cut off Pansa before he could reach the senatorial armies. Antony assumed Pansa had only four legions of recruits, but the previous night Hirtius had dispatched the Martian legion and Octavian's praetorian cohort to assist Pansa. Antony's legions collided with those of Pansa, in the village of Forum Gallorum. In the ensuing Battle of Forum Gallorum, Pansa's troops were routed and the general mortally wounded. However, instead of gaining a decisive victory, Antony was forced to withdraw when reinforcements under Hirtius crashed into his own exhausted ranks.

The battle
Six days after Forum Gallorum, the two armies met again in the vicinity of Mutina. Octavian's forces were now present and fought on the side of the remaining consul Hirtius. Although Antony was defeated Hirtius himself was killed in the attack on Antony's camp, leaving the army and republic leaderless. Octavian recovered his body and according to Suetonius, "in the thick of the fight, when the eagle-bearer of his legion was sorely wounded, he shouldered the eagle and carried it for some time." And now with a pro-praetorian imperium, he gained the deceased consul's legions.

Consequences
Mutina is essentially where Octavian turns from an inferior young man to an equal of Antony. After retreating over the Alps with the remains of his army, Antony soon recrossed the Alps having gathered an army of 17 legions and 10,000 cavalry (in addition to six legions left behind with Varius, according to Plutarch). However, soon after the battle, a truce was formed between Antony and Octavian at Bologna leading eventually to the Second Triumvirate with Marcus Aemilius Lepidus, Octavian and Mark Antony. They would set aside their differences and turn on the Senators involved in Caesar's assassination while assuming a 3-way dictatorship. Eventually in the ensuing power struggles many years later, Octavian would defeat Antony and Cleopatra at Actium in 31 BC and usher in the Principate, but Mutina was the milestone where Octavian first established himself as a force to be reckoned with. Without this victory, Octavian might never have achieved the prestige necessary to be looked upon as Caesar's successor, and the stability of the Empire might never have been established in the lasting manner which Octavian had decided for it.