The reign of Augustus initiated an era of relative peace known as the Pax Romana. The Roman world was largely free from large-scale conflict for more than two centuries, despite continuous wars of imperial expansion on the Empire's frontiers and the year-long civil war known as the "Year of the Four Emperors" over the imperial succession. Augustus dramatically enlarged the Empire, annexing Egypt, Dalmatia, Pannonia, Noricum, and Raetia; expanding possessions in Africa; expanding into Germania; and completing the conquest of Hispania. Beyond the frontiers, he secured the Empire with a buffer region of client states and made peace with the Parthian Empire through diplomacy. He reformed the Roman system of taxation, developed networks of roads with an official courier system, established a standing army, established the Praetorian Guard, created official police and fire-fighting services for Rome, and rebuilt much of the city during his reign. Augustus died in AD 14 at the age of 75. He probably died from natural causes, although there were unconfirmed rumors that his wife Livia poisoned him. He was succeeded as Emperor by his adopted son (also stepson and former son-in-law) Tiberius.
As a consequence of Roman customs, society, and personal preference Augustus (s-/; Classical Latin: [awˈɡʊstʊs]) was known by many names throughout his life:
Gaius Octavius Thurinus (s/): He received his birth name, after his biological father, in 63 BC. "Gaius" was his first name, "Octavius" was his surname, and "Thurinus" was his cognomen. Some of his political opponents referred him by his birth name in an attempt to insult him for changing his name multiple times. Augustus replied to them surprised that "using his old name was thought to be an insult". Historians typically refer to him by his family name, Octavius–sometimes anglicizing it to Octavian (n/)–between his birth and his adoption by Julius Caesar in 44 BC.
Gaius Julius Caesar Octavianus: After he was adopted by Julius Caesar, he took Caesar's name in accordance with Roman adoptionnaming standards. To further differentiate himself from his previous surname, he dropped "Octavianus" from his name and was known to his contemporaries as "Caesar" during this period. Select historians refer to him as "Octavian" between 44 BC and 27 BC. Two years after his adoption, he founded the Temple of Caesar additionally adding the title Divi Filius ("Son of the Divine") to his name in attempt to strengthen his political ties to Caesar's former soldiers, following the deification of Caesar. He assumed the name Gaius Julius Caesar Divi Filius as a means to that end.
Imperator Caesar Divi Filius: In 38 BC, Octavian replaced his praenomen "Gaius" and nomen "Julius" with Imperator, the title by which troops hailed their leader after military success. His name is roughly translated as "Commander Caesar, Son of the God".
Imperator Caesar Divi Filius Augustus: Following his 31 BC defeat of Mark Antony and Cleopatra, partly on his own insistence, the Roman Senate granted him the additional name, "Augustus", meaning "the increaser". He adopted his traditional name of Augustus thereafter. Historians use this name to refer to him from 27 BC until his death in AD 14.