|Octavian was the son of Julius Caesar’s niece. Octavian was 20 years old when Caesar was assassinated. Caesar had adopted him as his son posthumously. In 43 BCE, he formed the Second Triumvirate with Marc Antony and Lepidus. They defeated Brutus and Cassius and divided the empire with Octavian holding most of the West and Antony the East.|
In 33 BC, the Second Triumvirate ended, leaving Antony without legal authority. Octavian then began a campaign against him, declaring war against Cleopatra.