The Pompeian–Parthian invasion of 40 BC occurred after the Pompeians, backed by the Parthian Empire, had been defeated during the Liberators' civil war by Mark Antony and Octavian. King Orodes II sent a Parthian force under Prince Pacorus I and Pompeian General Quintus Labienus in 40 BC to invade the eastern Roman territories while Antony was in Egypt. Roman soldiers in Syria, many of whom had fought against Caesar during the last civil war, joined the force, and the Levant and much of Asia Minor were swiftly overrun by respectively Pacorus I and Labienus.