Final answer:
Mark Antony divorced Octavia around 32 BCE before his defeat at the Battle of Actium and his subsequent marriage to Cleopatra VII of Egypt.
Step-by-step explanation:
Mark Antony divorced Octavia and formed a significant alliance by marrying Cleopatra VII of Egypt. This pivotal moment in Roman history led to a series of events that culminated in the naval Battle of Actium in 31 BCE. Despite a previous disastrous campaign against Persia that left Antony's forces in a weakened state, it was not until after the defeat at Actium that Antony and Cleopatra's demise ensued. In the following year, 30 BCE, as Octavian (later known as Augustus) consolidated his power and invaded Egypt, witnessing the end of the Ptolemaic dynasty of Cleopatra and Antony. Therefore, while we know that Antony and Octavia's divorce occurred before Antony's subsequent marriage to Cleopatra, the exact year of the divorce isn't mentioned in the provided passages. Historical records suggest the divorce happened around 32 BCE, shortly before the war declared by Octavian and the ensuing Battle of Actium.