Gaius Suetonius Tranquillus (), commonly referred to as Suetonius ( ; c. AD 69 – after AD 122), was a Roman historian who wrote during the early Imperial era of the Roman Empire. His most important surviving work is a set of biographies of 12 successive Roman rulers, from Julius Caesar to Domitian, properly titled De vita Caesarum. Other works by Suetonius concerned the daily life of Rome, politics, oratory, and the lives of famous writers, including poets, historians, and grammarians. A few of these books have partially survived, but many have been lost. Life Gaius Suetonius Tranquillus was probably born about AD 69, a date deduced from his remarks describing himself as a "young man" 20 years after Nero's death. His place of birth is disputed, but most scholars place it in Hippo Regius, a small north African town in Numidia, in modern-day Algeria. It is certain that Suetonius came from a family of moderate social position, that his father, Suetonius Laetus, was a tribune belonging to the equestrian order (tribunus angusticlavius) in Legio XIII Gemina, and that Suetonius was educated when schools of rhetoric flourished in Rome. Suetonius was a close friend of senator and letter-writer Pliny the Younger. Pliny describes him as "quiet and studious, a man dedicated to writing". Pliny helped him buy a small property and interceded with the Emperor Trajan to grant Suetonius immunities usually granted to a father of three, the ius trium liberorum, because his marriage was childless. Through Pliny, Suetonius came into favour with Trajan and Hadrian. Suetonius may have served on Pliny's staff when Pliny was imperial governor (legatus Augusti pro praetore) of Bithynia and Pontus (northern Asia Minor) between 110 and 112. Under Trajan he served as secretary of studies (precise functions are uncertain) and director of Imperial archives. Under Hadrian, he became the emperor's secretary. Hadrian later dismissed Suetonius for his alleged affair with the empress Vibia Sabina. Works The Twelve Caesars Suetonius is mainly remembered as the author of De Vita Caesarum—translated as The Life of the Caesars, although a more common English title is The Lives of the Twelve Caesars or simply The Twelve Caesars—his only extant work except for the brief biographies and other fragments noted below. The Twelve Caesars, probably written in Hadrian's time, is a collective biography of the Roman Empire's first leaders, Julius Caesar (the first few chapters are missing), Augustus, Tiberius,