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, 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, probably from natural causes. Persistent rumors, substantiated somewhat by numerous deaths in the imperial family, have claimed his wife Livia poisoned him. He was succeeded as emperor by Livia's son – also his by adoption and former husband of his only biological daughter Julia – Tiberius, who consolidated the Principate into a de facto autocratic monarchy, the Roman Empire.