Augustus dramatically enlarged the Empire, annexing Egypt, Dalmatia, Pannonia, Noricum and Raetia, expanding possessions in Africa, and completing the conquest of Hispania, but suffered a major setback in Germania. 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, 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, probably from natural causes. Persistent rumors, substantiated somewhat by deaths in the imperial family, have claimed his wife Livia poisoned him. He was succeeded as emperor by his adopted son Tiberius, Livia's son and also former husband of Augustus' only biological daughter Julia.