Originally named Gaius Octavius, he was born into an old and wealthy equestrian branch of the plebeian "gens" Octavia. His maternal great-uncle Julius Caesar was assassinated in 44 BC, and Octavius was named in Caesar's will as his adopted son and heir, after which he took the name Gaius Julius Caesar, though later historians would take to calling him Octavian to avoid confusion with his great-uncle. He, Mark Antony, and Marcus Lepidus formed the Second Triumvirate to defeat the assassins of Caesar. Following their victory at the Battle of Philippi (42 BC), the Triumvirate divided the Roman Republic among themselves and ruled as "de facto" dictators. The Triumvirate was eventually torn apart by the competing ambitions of its members; Lepidus was exiled in 36 BC, and Antony was defeated by Octavian at the Battle of Actium in 31 BC.