The rise of T. Aurelius Fulvus Boionius Arrius Antoninus, simply known as Antoninus Pius, could be considered an unlikely yet fortunate turn of events. His reign, though far from one of perpetual peace as has often been described, was one of political stability, economic prosperity and consistent military strength. Antoninus was born in September, AD 86 in the city of Lanuvium very near Rome.
Despite his family heritage originating from Narbonensis (the southern coast of Gaul), his grandfather (Titus Aurelius Fulvus) had risen to the consulship twice and his father (Aurelius Fulvus) had served once in the same capacity. To further cement the prestige and aristocratic lineage of his family the future emperor's maternal grandfather Arrius Antoninus had also served two consulships. When his father died at a young age Antoninus was left in the care of his grandfathers and his mother, Arria Fadilla remarried yet another man of consular rank, Julius Lupus.
Unfortunately, like his predecessors Trajan and Hadrian, there are few surviving written accounts for the life of Antoninus. For example, Cassius Dio's work is terribly fragmented, essentially leaving us with roughly 6 short paragraphs of unrelated (though still valuable) material. The main source for Antoninus, the Historia Augusta credited to Julius Capitoninus, provides much more detail but has long been debated by scholars for its accuracy. As such, little is known of the life of Antoninus prior to his accession. He was married to Annia Galeria Faustina, with whom he had four children (2 sons and 2 daughters). Though three of the children did not figure in imperial affairs, one daughter, Faustina the Younger was later to marry Antoninus' nephew and adopted heir Marcus Aurelius. Antoninus seemingly rose in a typical fashion for a young man with his familial legacy, serving as quaestor and praetor before reaching the consulship under Hadrian around AD 120.
Antoninus' rise under Hadrian continued with an appointment as one of four consular administrators of Italy, which included the territory encompassing Hadrian's own estates. By the early 130's AD, Antoninus' Senatorial career reached its pinnacle, when he was appointed governor of the prestigious province of Asia Minor. While the relationship between Hadrian and Antoninus is largely unknown, the course of the relationship took a decided and unexpected turn with the death of Hadrian's heir Lucius Ceionius Commodus in AD 138. Antoninus' position as a distinguished and respected proconsular Senator made him an attractive alternative, an alternative that would prove invaluable to uninterrupted succession and Hadrian's legacy (including his deification). Hadrian named Antoninus as his second choice for adopted heir with the condition that he in turn adopt his own nephew Marcus Aelius Aurelius Verus (later Marcus Aurelius) and the son of Hadrian's first named heir Lucius Aelius Aurelius Commodus (later Lucius Verus). Antoninus was given time to consider the proposition (reflective of both his and Hadrian's effectiveness as leaders), before finally agreeing to the terms. Hadrian's new heir was effectively given joint imperial power, proconsular imperium and tribunician authority, allowing him to learn "on the job" before Hadrian passed away in July of the same year (AD 138).
Antoninus succeeded Hadrian at the age of 51 years old, likely not having been expected to reign for long (hence partly explaining the desire for him to succeed Hadrian with pre-determined heirs in place). Unlike Hadrian, who succeeded Trajan under a cloud of uncertain legality regarding his adoption and with some political opposition, Antoninus' position had been sufficiently secured through the public adoption process. Despite his complete absence of military experience (at least as far as the historical record provides) Antoninus would rule the empire for 23 prosperous and largely peaceful years (coupled with the reigns of M. Aurelius and his son/successor Commodus the peaceful uninterrupted succession would total some 55 years).
Unlike his predecessors, Trajan who campaigned for extended periods in Dacia, Armenia and Parthia, and Hadrian who toured the provinces of the entire empire, Antoninus governed the empire almost exclusively from the city of Rome and the surrounding regional territory of central Italy. A career politician and aristocrat, Antoninus seemed to be "at home" within reach of Senatorial peers and launched a reign consisting of conservative fiscal policy, diplomatic appeasement rather than aggression and continued social welfare programs.