Actium followed Julius Caesar's assassination, the Liberators' War, and the collapse of the Second Triumvirate. Once Octavian sidelined Marcus Aemilius Lepidus, power narrowed to Antony and Octavian. Antony still possessed two consuls and roughly a third of the Senate, while Octavian held about two thirds plus experienced commanders including Agrippa. Opening the video here clarifies why Actium was both a civil-war fleet action and a contest over which Roman coalition would dominate the state.
Notable Point · 0:27-1:54
The Second Triumvirate narrows to Antony and Octavian
After the Liberators' War and Octavian's removal of Lepidus, the Second Triumvirate narrowed into a struggle between Antony's senatorial coalition and Octavian's larger, more experienced camp.