At the beginning, Lepidus' possession of the provinces of
Hispania and
Narbonese Gaul was confirmed, and he agreed to hand over 7 legions to Octavian and Antony to continue the struggle against Brutus and Cassius for eastern Roman territory; in the event of defeat, Lepidus' territories would provide a fall-back position. Antony retained Cisalpine Gaul and hegemony over Gaul itself, and Octavian held Africa and was given nominal authority over Sicily and Sardinia. According to historian Richard Weigel, Octavian's share at this stage was "practically humiliating"; all the most important provinces went to Antony and Lepidus, though transfer of Lepidus' legions to Octavian meant that Lepidus was "effectively eliminating himself as an equal partner" in future.
After the victory, Antony and Octavian agreed to divide the provinces of the Republic into spheres of influence. Octavian — who had begun calling himself "
Divi filius" ("son of the divinity") after Caesar's deification as Divus Julius ("the Divine Julius") and now styled himself simply "
Imperator Caesar" — took control of the West, Antony of the East. As a result, the province of Cisalpine Gaul was absorbed into Italy. Narbonese Gaul was absorbed into Gallia Comata, creating a unified Gaul, and was thus taken over by Antony. Octavian took over Spain from Lepidus. Lepidus himself was left with nothing, but was offered the prospect of control over Africa. The excuse given for this was a report that Lepidus had been traitorously negotiating with
Sextus Pompey. If he were proved innocent he would have Africa. Octavian returned to Rome to administer the distribution of land to his veterans. Antony remained in the east to bring Brutus and Cassius' former territories under triumvirate control.
Octavian's land redistribution caused widespread tensions, as farmers were dispossessed in favour of soldiers. Antony's brother
Lucius Antonius, who was serving as Consul, stood up for the dispossessed farmers. The conflict led to the
Perusine War, in which Lucius gathered an army of supporters to challenge Octavian. He was encouraged by Mark Antony's wife
Fulvia. Lepidus held Rome with two legions while Octavian left to gather his army, but Lucius defeated Lepidus, who was forced to flee to Octavian. As Octavian advanced on Rome, Lucius withdrew to Perusia (Perugia), where he was besieged by Octavian in the winter of 41-40 BC. He finally surrendered in exchange for clemency. The outcome was that Lepidus was confirmed as governor of Africa, acquiring six of Antony's legions, leaving Octavian as the sole power in Italy, with his own loyal legions in control. When Antony's supporter Calenus, governor of Gaul, died, Octavian took over his legions, further strengthening his control over the west. This new distribution of power among the triumvirs was confirmed by the Treaty of Brundisium in September 40 BC. At around the same time, Antony's wife Fulvia died. Octavian arranged for Antony to marry his sister,
Octavia, as a symbol of the renewed alliance.
The economic problems caused by the eviction of established farmers were exacerbated by the control of Sextus Pompey over Sicily, Corsica and Sardinia. Pompey's navy regularly intercepted Roman shipping, leading to problems with the grain supply. In 39 BC Antony and Octavian decided to negotiate an agreement to stop the piracy. According to Appian, Sextus hoped to replace Lepidus as the third triumvir, but instead he was confirmed in possession of the islands by the
Pact of Misenum, in return agreeing to stop his piracy.
Octavian accused Lepidus of attempting to usurp power and fomenting rebellion. Humiliatingly, Lepidus' legions in Sicily defected to Octavian and Lepidus himself was forced to submit to him. Lepidus was stripped of all his offices except that of Pontifex Maximus. Octavian sent him into exile in
Circeii.