Who Was Antoninus Pius?:
Antoninus Pius was one of the so-called "5 good emperors" of Rome. Although the piety of his sobriquet is associated with his actions on behalf of his predecessor (Hadrian), Antoninus Pius was compared with another pious Roman leader, the second king of Rome (Numa Pompilius). Antoninus was praised for qualities of clemency, dutifulness, intelligence, and purity.
The era of the 5 good emperors was one where imperial succession was not based on biology. Antoninus Pius was the adoptive father of Emperor Marcus Aurelius and the adopted son of Emperor Hadrian. He ruled from A.D. 138-161.
Family of Antoninus Pius:
Titus Aurelius Fulvus Boionius Antoninus Pius or Antoninus Pius was the son of Aurelius Fulvus and Arria Fadilla. He was born at Lanuvium (a Latin city southeast of Rome) on September 19, A.D. 86, and spent his childhood with his grandparents. Antoninus Pius' wife was Annia Faustina.
The title "Pius" was awarded Antoninus by the Senate.
Career of Antoninus Pius:
Antoninus served as quaestor and then praetor before becoming consul in 120 with Catilius Severus. Hadrian named him one of 4 ex-consuls to have jurisdiction over Italy. He was proconsul in Asia. After his proconsulship, Hadrian used him as a consultant. Hadrian had adopted Aelius Verus as heir, but when he died, Hadrian adopted Antoninus (February 25, 138 A.D.) in a legal arrangement that entailed Antoninus' adoption of Marcus Aurelius and Lucius Verus (from then on Verus Antoninus) the son of Aelius Verus. At the adoption, Antoninus received proconsular imperium and tribunician power.
Antoninus Pius as Emperor:
Upon taking office as emperor when his adopted father, Hadrian, died, Antoninus had him deified. His wife was titled Augusta (and posthumously, deified) by the Senate, and he was given the title Pius (later, also Pater Patriae 'Father of the Country').
Antoninus left Hadrian's appointees in their offices. Although he did not participate in person, Antoninus fought against the Britons, made peace in the East, and fought tribes of Germans and Dacians (see Map of the Empire). He dealt with rebellions of Jews, Achaeans, and Egyptians, and suppressed the pillaging Alani. He would not allow senators to be executed.
Generosity of Antoninus:
As was customary, Antoninus gave money to the people and the troops. The Historia Augusta mentions that he lent money at the very low interest rate of 4%. He founded an order for poor girls that was named after his wife, Puellae Faustinianae 'Faustinian Girls'. He refused legacies from people with children of their own.
Antoninus Pius died in March 161. Historia Augusta describes the cause of death: "after he had eaten too freely some Alpine cheese at dinner he vomited during the night, and was taken with a fever the next day." He died a few days later. His daughter was his principal heir. He was deified by the Senate.
Antoninus Pius on Slaves:
A passage about Antoninus Pius from Justinian ["Roman Slave Law and Romanist Ideology," by Alan Watson; Phoenix, Vol. 37, No. 1 (Spring, 1983), pp. 53-65]
[A]... rescript of Antoninus Pius which is recorded in Justinian's Justinian's Institutes:
J. 1.8. 1: Therefore slaves are in the power of their masters. This power indeed comes from the law of nations; for we can see that among all nations alike masters have power of life and death over their slaves, and whatever is acquired through a slave is acquired for the master. (2) But nowadays, it is permitted to no one living under our rule to ill treat his slaves immoderately and without a cause known to the law. For by a constitution of the deified Antoninus Pius whoever kills his slave without cause is to be punished no less than one who kills the slave of another. And even excessive severity of masters is restrained by a constitution of the same Emperor. For when he was consulted by certain provincial governors about those slaves who flee to a holy temple or to a statue of the Emperor, he gave the ruling that if the severity of the masters seems intolerable they are compelled to sell their slaves on good terms, and the price is to be given to the owners. For it is to the advantage of the state that no one use his property badly. These are the words of the rescript sent to Aelius Marcianus: "The power of masters over their slaves should be unlimited, nor should the rights of any persons be detracted from. But it is in the interest of masters that help against savagery or hunger or intolerable injury should not be denied to those who rightly entreat for it. Investigate, therefore, the complaints of those from the family of Julius Sabinus who fled to the statue, and if you find they were more harshly treated than is fair or afflicted by shameful injury, order them to be sold so that they do not return to the power of the master. Let Sabinus know that, if he attempt to circumvent my constitution I will deal severely with his behavior."
Lives of the Later Caesars