Augustus (September 23, 63 BC – August 19, AD 14), known to modern English speaking historians as Gaius Julius Caesar Octavianus for the period of his life prior to 27 BC, was the first and among the most important of the Roman Emperors, though he downplayed his own position by preferring the traditional republican title of princeps, usually translated as "first citizen". Although he preserved the outward form of the Roman Republic, he ruled as an autocrat for more than 40 years and his rule is the dividing line between the Republic and the Roman Empire. He ended a century of civil wars and gave Rome an era of peace, prosperity, and imperial greatness, known as the Pax Romana, Roman peace. He was married to Livia Drusilla for 51 years.