Why did Roman supporters abandon Mark Antony before the Battle of Actium?

Before the Battle of Actium, many of Mark Antony’s Roman supporters abandoned him due to a combination of effective propaganda, shifting political loyalties, and the deteriorating state of his military campaign.

Octavian waged a successful propaganda war, convincing the Roman upper class and the western provinces that Antony was sacrificing Roman interests to become a Hellenistic king in Alexandria. This narrative was bolstered by Antony’s relationship with Cleopatra, his decision to grant Roman territories to her and their children, and his apparent desire to rule from Egypt rather than Rome.123

The morale of Antony’s forces further declined as he lost ground to Octavian’s forces, a situation exacerbated by Cleopatra’s presence at his headquarters, which many of his leading Roman supporters opposed. As Antony’s military position weakened and provisions became scarce, his supporters increasingly defected to Octavian, who had also intimidated many of Antony’s remaining aristocratic friends into joining his cause. By the time of the battle, these factors had significantly eroded the loyalty of his followers, leading to widespread desertions.124