In Roman history, an alliance formed (43 bc ) by Octavius (later Augustus ), Mark Antony, and Lepidus. The triumvirs were to have consular power for three years; they appointed magistrates, and their decrees were valid as laws. The empire was divided among them: Octavius obtained Africa and the islands; Antony, Gaul; Lepidus, Spain and Narbonensis. The alliance was followed by the overthrow of the republicans under Cassius and Brutus at Philippi (42). Eventually, Lepidus, whose position in the alliance was minor, was banished; by the Treaty at Brundisium, Octavian received the West and Antony the East. Their union was broken in 31, and Antony was defeated at Actium. This left Octavius sole ruler, and, in gradual steps, he completed the transformation of Rome from a republic to an empire, as Augustus, its first emperor.