The final years of the Roman Republic were characterised by the political and military conflict between Octavian and Antony, which culminated in Octavian's victory at Actium in 31 BC. But how had it come to this?

Lepidus had already been eliminated after attempting to seize Sicily from Sextus Pompeius in 36 BC; as Pontifex Maximus, he saved his life, but he was forced to retreat to Circeum. The Second Triumvirate was therefore destined to end, as was indeed expected at the end of 33 BC.

The two remaining triumvirs represented opposing worlds. Octavian, fully recognised in the West as Caesar's sole heir, controlled the Curia thanks to his authority and, above all, the support of Caesar's veterans. Antony, on the other hand, aided by his relationship with Cleopatra and the Egyptian context, ended up adopting an absolutist conception of power, something an ancient Roman would have viewed with hostility.

The opportunity for Octavian to definitively resolve the issue arose following two events: his sister Octavia's repudiation of his marriage to Cleopatra, and Antony's triumph in Alexandria in 34 BC for the conquest of Armenia, rather than in Rome. Furthermore, after dividing the Eastern territories among his children with Cleopatra, Antony recognised Caesarion as Caesar's sole true heir.

Octavian then decided to personally remove Antony's will, guarded by the Vestal Virgins, and read it before the Senate. In it, Antony requested to be buried in Egypt, acknowledged Caesar's paternity of Caesarion, and confirmed the assignment of the eastern territories to his sons. The will was likely considered a forgery even at the time—or at least many in positions of power must have entertained doubts about its authenticity—but Octavian's propaganda moved swiftly. He persuaded all the municipalities of Italy and the West, outraged by Antony and fearful of seeing Cleopatra queen of the Roman world, to swear fealty to him. In the Res Gestae Divi Augusti, the future princeps presented this oath in solemn terms; however, it is believed to have caused considerable discontent, since the financial burden of the impending war fell on the Italians.

Octavian ultimately secured the Senate's declaration of war against Cleopatra (not Antony), thus presenting the conflict as a war against an East that had ensnared and corrupted a Roman.